Microwaves and cellular immunity. II. Immunostimulating effects of microwaves and naturally occurring antioxidant nutrients

The effect of 8.15-18 GHz (1 Hz within) microwave radiation at a power density of 1 microW/cm2 on the tumor necrosis factor (TNF) production and immune response was tested. A single 5 h whole-body exposure induced a significant increase in TNF production in peritoneal macrophages and splenic T cells. The mitogenic response in T lymphocytes increased after microwave exposure. The activation of cellular immunity was observed within 3 days after exposure. The diet containing lipid-soluble nutrients (beta-carotene, alpha-tocopherol and ubiquinone Q9) increased the activity of macrophages and T cells from irradiated mice. These results demonstrate that irradiation with low-power density microwaves stimulates the immune potential of macrophages and T cells, and the antioxidant treatment enhances the effect of microwaves, in particular at later terms, when the effect of irradiation is reduced.     

The effects of low level microwaves on the fluidity of photoreceptor cell membrane

Due to the extensive use of electromagnetic fields in everyday life, more information is required for the detection of mechanisms of interaction and the possible side effects of electromagnetic radiation on the structure and function of the organism.In this paper, we study the effects of low-power microwaves (2.45 GHz) on the membrane fluidity of rod photoreceptor cells. The retina is expected to be very sensitive to microwave irradiation due to the polar character of the photoreceptor cells [Biochim. Biophys. Acta 1273 (1995) 217] as well as to its high water content [Stud. Biophys. 81 (1981) 39].     

Microwaves and cellular immunity. I. Effect of whole body microwave irradiation on tumor necrosis factor production in mouse cells

Whole body microwave sinusoidal irradiation of male NMRI mice with 8.15-18 GHz (1 Hz within) at a power density of 1 microW/cm2 caused a significant enhancement of TNF production in peritoneal macrophages and splenic T lymphocytes. Microwave radiation affected T cells, facilitating their capacity to proliferate in response to mitogenic stimulation. The exposure duration necessary for the stimulation of cellular immunity ranged from 5 h to 3 days. Chronic irradiation of mice for 7 days produced the decreasing of TNF production in peritoneal macrophages. The exposure of mice for 24 h increased the TNF production and immune proliferative response, and these stimulatory effects persisted over 3 days after the termination of exposure. Microwave treatment increased the endogenously produced TNF more effectively than did lipopolysaccharide, one of the most potential stimuli of synthesis of this cytokine. The role of microwaves as a factor interfering with the process of cell immunity is discussed.     

聚苯胺/蒙脱土纳米复合材料的制备及吸波性能研究

以十二烷基苯磺酸(DBSA)作为乳化剂和掺杂剂,通过乳液聚合的方法制备了DBSA掺杂聚苯胺/蒙脱土(PANI-DBSA/MMT)纳米复合物,并对其微波吸收特性进行了研究.通过X射线衍射(XRD)、傅立叶红外(FT-IR)和四探针测试仪对复合物进行了初步表征.结果表明,PANI-DBSA/MMT复合物中MMT层间距离明显扩大,纳米复合物中的PANI以emeraldine盐的形式存在,是一种典型的插层型纳米复合物.利用HP8722ES矢量网络分析仪测量了2 mm厚、PANI-DBSA/MMT含量为50 wt%的试样在2.0~18 GHz的复介电常数和复磁导率,经计算得到以反射损耗表示的微波吸收曲线,发现PANI-DBSA/MMT纳米复合物在9.1~12.5 GHz范围内反射损耗小于-10 dB,在11 GHz处存在的最大反射损耗为-15.8 dB.     

The temperature effect during pulse application on cell membrane fluidity and permeabilization

Cell membrane permeabilization is caused by the application of high intensity electric pulses of short duration. The extent of cell membrane permeabilization depends on electric pulse parameters, characteristics of the electropermeabilization media and properties of cells exposed to electric pulses. In the present study, the temperature effect during pulse application on cell membrane fluidity and permeabilization was determined in two different cell lines: V-79 and B16F-1. While cell membrane fluidity was determined by electron paramagnetic resonance (EPR) method, the cell membrane electropermeabilization was determined by uptake of bleomycin and clonogenic assay. A train of eight rectangular pulses with the amplitude of 500 V/cm, 700 V/cm and 900 V/cm in the duration of 100 micros and with repetition frequency 1 Hz was applied. Immediately after the pulse application, 50 microl droplet of cell suspension was maintained at room temperature in order to allow cell membrane resealing. The cells were then plated for clonogenic assay. The main finding of this study is that the chilling of cell suspension from physiological temperature (of 37 degrees C) to 4 degrees C has significant effect on cell membrane electropermeabilization, leading to lower percent of cell membrane permeabilization. The differences are most pronounced when cells are exposed to electric pulse amplitude of 900 V/cm. At the same time with the decreasing of temperature, the cell membranes become less fluid, with higher order parameters in all three types of domains and higher proportion of domain with highest order parameter. Our results indicate that cell membrane fluidity and domain structure influence the electropermeabilization of cells, however it seems that some other factors may have contributing role.     

Effect of 1.7 MHz ultrasound on a gas-vacuolate cyanobacterium and a gas-vacuole negative cyanobacterium

Ultrasonic signals propagated through medium were directly applied to unicellular cyanobacterium cell surfaces to investigate the biological effects induced by ultrasound. The gas-vacuolate cyanobacterium Microcystis aeruginosa and the gas-vacuole negative cyanobacterium Synechococcus PCC 7942 responded differently to ultrasound. When M. aeruginosa was irradiated by 1.7 MHz ultrasound at 0.6 W cm(-2) every day, it showed a decrease of nearly 65% in biomass increment, and this group's generation time increased twice as much as the control. While Synechococcus culture irradiated every day still grew as fast as the control, and its final biomass was as much as the control. The value of the electric conductivity change (Deltasigma) sharply increased in Microcystis suspension during the exposure process, which revealed more ultrasonic cavitation yield in liquid related to the gas-vacuolate cyanobacteria. The relative malondialdehyde (MDA) content, a quantitative indicator of lipid peroxidation, increased by 65% in Microcystis cells and 9% in Synechoccus cells after ultrasonic irradiation. Moreover, the membrane permeability, quantified by measuring the relative amount of electrolyte leaking out of cells, increased to more than 60% in the Microcystis cells. The results indicated that Microcystis cells were susceptible to ultrasonic stress. According to Rayleigh-Plesset's bubble activation theory, 1.7 MHz ultrasound approached the eigenfrequency of gas-vacuolate cells. The present investigation suggested the importance of the cavitational effect relative to intracellular gas-vacuoles in the loss of cell viability. In summary, 1.7 MHz ultrasonic irradiation was effective in preventing water-bloom forming cyanobacteria from growing rapidly due to changes in the functioning and integrity of cellular and subcellular structures.     

Osmotically induced membrane tension facilitates the triggering of living cell electropermeabilization

Very little is known about the molecular mechanisms supporting living cell membrane electropermeabilization. This concept is based on the local membrane permeability induced by cell exposure to brief and intense external electric field pulses. During the electric field application, an electro-induced membrane electric potential difference is created that is locally associated with the dielectric properties of the plasma membrane. When the new membrane electric potential difference locally reaches a critical value, a local alteration of the membrane structure is induced and leads to reversible permeabilization. In our study, we attempted to determine whether mechanical tension could modulate the triggering of membrane electropermeabilization. Change in lateral tension of Chinese Hamster Ovary cell membrane has been osmotically induced. Cell electropermeabilization was performed in the minute time range after the osmotic stress, i.e., before the regulatory volume decrease being activated by the cell. Living cell electropermeabilization was analyzed on cell population using flow cytometry. We observed that electropermeabilization triggering was significantly facilitated when the lateral membrane tension was increased. The main conclusion is that the critical value of transmembrane potential needed to trigger membrane electropermeabilization, is smaller when the membrane is under lateral mechanical constraint. This supports the hypothesis that both mechanical and electrical constraints play a key role in transient membrane destabilization.     

Electrokinetic and surface chemical characterizations of an irradiated microfiltration polysulfone membrane: comparison of two irradiation doses

The effect of ionizing radiation on the surface and electrokinetic characteristic parameters for a porous membrane of pore size 0.2 mum is determined and correlated with the irradiation dose (10 and 80 J/kg). Changes in NaCl permeability and membrane system electrical resistance determined from diffusion and impedance spectroscopy measurements are consistent with the increase of membrane pore radii/porosity, in agreement with SEM micrographs and reported results. Low irradiation dose seems to clean the membrane surface of impurities, according to XPS results, but the increase of irradiation doses could affect surface roughness. Due to the relatively high pore radius, ion transport numbers are practically independent of radiation and dose, but irradiation slightly modifies the membrane solution interface by increasing its weakly electronegative character, which could be of interest in the ultrafiltration of proteins or macromolecules.     

AN ACTION SPECTRUM FOR ULTRAVIOLET RADIATION-INDUCED MEMBRANE DAMAGE IN Escherichia coli K-12

A wild-type Escherichia coli K-12 strain was irradiated using monochromatic radiation in the range 254 to 405 nm. A measure of the cell membrane damage induced at each wavelength was investigated by comparing cell viability after irradiation on nutrient agar and on minimal medium containing either a low or high inorganic salt concentration. An action spectrum for lethality and for cell membrane damage was then determined. From 254 to 310 nm lethality closely corresponded to the absorption spectrum of DNA, and there was no indication of membrane damage. However, above a wavelength of 310 nm, the direct absorption of radiation by DNA could not account for the sensitivity observed. Moreover, at wavelengths longer than 310 nm, cell membrane damage was induced and by an increasing factor up to a peak at 334 nm. At the longer wavelengths of 365 and 405 nm, there was a gradual decrease from the peak of damage to cell membranes induced by 334 nm radiation. These results indicate that cell membrane damage may contribute significantly to near-UV radiation-induced cell lethality in wild-type E. coli K-12.     

On‐chip technology for single‐cell arraying,electrorotation‐based analysis and selective release

This paper reports a method for label‐free single‐cell biophysical analysis of multiple cells trapped in suspension by electrokinetic forces. Tri‐dimensional pillar electrodes arranged along the width of a microfluidic chamber define actuators for single cell trapping and selective release by electrokinetic force. Moreover, a rotation can be induced on the cell in combination with a negative DEP force to retain the cell against the flow. The measurement of the rotation speed of the cell as a function of the electric field frequency define an electrorotation spectrum that allows to study the dielectric properties of the cell. The system presented here shows for the first time the simultaneous electrorotation analysis of multiple single cells in separate micro cages that can be selectively addressed to trap and/or release the cells. Chips with 39 micro‐actuators of different interelectrode distance were fabricated to study cells with different sizes. The extracted dielectric properties of Henrietta Lacks, human embryonic kidney 293, and human immortalized T lymphocytes cells were found in agreements with previous findings. Moreover, the membrane capacitance of M17 neuroblastoma cells was investigated and found to fall in in the range of 7.49 ± 0.39 mF/m².     

The sensitivity of cells and tissues to exogenous fields: effects of target system initial state

The effect of the initial biochemical or metabolic state of a cell membrane target pathway on its sensitivity to exogenous electromagnetic (EMF) fields is considered. It is shown that the resting or initial transmembrane voltage can affect the frequency response of the membrane pathway and substantially alter the signal to thermal noise threshold (SNR) of the target. EMF sensitivity is examined using a model which describes the response to applied fields of both single cells and cells in gap junction contact via a distributed parameter electrical circuit analog, wherein a voltage-dependent membrane impedance, relating to the initial biochemical state of the target cell(s), is considered. Application of the Hodgkin-Huxley K(+)-conduction pathway membrane to this model results, at a given transmembrane voltage, in a preferential array response to applied field frequencies in the 1-100 Hz range, centered at approximately 16 Hz for 1-10 mm array lengths. Extension of the model to consider the voltage dependence of the Hodgkin-Huxley K+ pathway results in a significant modulation of array frequency response with changing membrane resting potential. The result is EMF sensitivity (SNR) depends upon the initial state of the target tissue, providing a possible explanation of why, e.g., repairing, rather than resting, bone exhibits a physiologically relevant response to certain weak EMF signals.     

Oxidative Effects during Irreversible Electroporation of Melanoma Cells—In Vitro Study

Irreversible electroporation (IRE) is today used as an alternative to surgery for the excision of cancer lesions. This study aimed to investigate the oxidative and cytotoxic effects the cells undergo during irreversible electroporation using IRE protocols. To do so, we used IRE-inducing pulsed electric fields (PEFs) (eight pulses of 0.1 ms duration and 2–4 kV/cm intensity) and compared their effects to those of PEFs of intensities below the electroporation threshold (eight pulses, 0.1 ms, 0.2–0.4 kV/cm) and the PEFs involving elongated pulses (eight pulses, 10 ms, 0.2–0.4 kV/cm). Next, to follow the morphology of the melanoma cell membranes after treatment with the PEFs, we analyzed the permeability and integrity of their membranes and analyzed the radical oxygen species (ROS) bursts and the membrane lipids’ oxidation. Our data showed that IRE-induced high cytotoxic effect is associated both with irreversible cell membrane disruption and ROS-associated oxidation, which is occurrent also in the low electric field range. It was shown that the viability of melanoma cells characterized by similar ROS content and lipid membrane oxidation after PEF treatment depends on the integrity of the membrane system. Namely, when the effects of the PEF on the membrane are reversible, aside from the high level of ROS and membrane oxidation, the cell does not undergo cell death.     

Electrokinetic migration across artificial liquid membranes. New concept for rapid sample preparation of biological fluids

Basic drug substances were transported across a thin artificial organic liquid membrane by the application of 300 V d.c. From a 300 microl aqueous donor compartment (containing 10 mM HCl), the drugs migrated through a 200 microm artificial liquid membrane of 2-nitrophenyl octyl ether immobilized in the pores of a polypropylene hollow fiber, and into a 30 microl aqueous acceptor solution of 10 mM HCl inside the lumen of the hollow fiber. The transport was forced by an electrical potential difference sustained over the liquid membrane, resulting in electrokinetic migration of drug substances from the donor compartment to the acceptor solution. Within 5 min of operation at 300 V, pethidine, nortriptyline, methadone, haloperidol, and loperamide were extracted with recoveries in the range 70-79%, which corresponded to enrichments in the range 7.0-7.9. The chemical composition of the organic liquid membrane strongly affected the permeability, and may serve as an efficient tool for controlling the transport selectivity. Water samples, human plasma, and human urine were successfully processed, and in light of the present report, electrokinetic migration across thin artificial liquid membranes may be an interesting tool for future isolation within chemical analysis.     

Erythrocyte response to near-infrared radiation

The effects of NIR (near-infrared radiation 700-2,000 nm) on bovine erythrocytes in plasma was studied as a continuation of earlier studies. Cell shape was observed and the changes of ratio of hemolysis and electrokinetic potential measured as a function of irradiation time. After 10 min of irradiation, the shape of erythrocyte cells was mainly echinocytic. When these cells were incubated at 311 K for 24 h they regained their initial shape, but fresh erythrocytes that were irradiated for 30 min and aged in vitro did not. These phenomena are due to: (1) the absorption of NIR excitation by hemoglobin; the primary photochemical process being the photo-dissociation of oxyhemoglobin to deoxyhemoglobin. Resulting shape and ratio of hemolysis, structural changes and oxidative stress follow higher deoxyhemoglobin concentration. (2) The absorption of the NIR excitation by proteins, water and lipids. After NIR absorption the membrane surface dehydrates, leading to enhanced protonation and dissociation of hydrogen-bonded complexes. This in turn leads to a change in electrokinetic potential.     

Synthesis of composite of ZnO spheres with polyaniline and their microwave absorption properties

Three-dimensional (3D) ZnO microspheres with the composite of polyaniline (PANI) have been successfully synthesized by one-pot solvothermal and in-suit polymerization method. The obtained microspheres were uniform having the diameter of 4 μm–7 μm. These microspheres, inside cushion of PANI polymer, exhibit excellent microwave absorption properties. Composite of ZnO microspheres with PANI increased the complex permeability and enhanced the dielectric loss. Thus, the microwave absorption properties of the composite have been intensified. Despite the fact that the composite of ZnO with PANI herein dissipate the microwaves by dielectric loss, their performance is admirable compared to most of PANI-based composites reported. The morphological, structural and spectral properties have been investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and the Fourier transform infrared (FT-IR). It is found that the maximum reflection loss value of [email protected] reaches ?41 dB at 14 GHz with a thickness of 3.5 mm that is superior to the previously reported composite of PANI with other materials.     

DAMAGE BY SOLAR RADIATION AT DEFINED WAVELENGTHS. INVOLVEMENT OF INDUCIBLE REPAIR SYSTEMS

Abstract The susceptibility of bacteriophage damaged by solar-ultraviolet (UV, 290-380 nm) radiations at denned wavelengths and by radiation at a visible wavelength (405 nm) to the Weigle reactivation system induced by far-UV (254 nm) irradiation of the host cell has been studied in a repair competent strain of Escherichia coli . The sector of inducible repair diminishes with wavelength, being very small after 313 nm irradiation and absent after irradiation at longer wavelengths. However, irradiation of bacteria at wavelengths as long as 313 nm induces a bacteriophage reactivation system as effectively as radiation at 254 nm in both the repair competent and an excision deficient host cell. At longer wavelengths pre-irradiation of the repair competent host cell enhances reactivation of 254 nm irradiated bacteriophage but the reactivation is smaller and the process quite distinct from that induced in the 254-313 nm region. We conclude that, with increasing wavelength, damage induced by solar UV radiations becomes increasingly less susceptible to repair systems induced by far-UV (pyrimidine dimers) and that this type of inducible repair system is no longer induced by wavelengths longer than 313 nm.     

Differential interference contrast microscopy for real-time dynamics and manipulation of single cells in microchannels

Nomarski differential interference contrast (DIC) microscopy was used for real-time dynamics of intact single cells in various microchannels for adaptation to microfluidic chip application. The cheek cell was chosen as a model, single cell and the dynamics was measured at the microchannels. The image resolution of single cell was shaper and more distinct in DIC than in conventional microscopy. The individual single living cells were also manipulated by both hydrodynamic and electrokinetic flow-driving forces at the microchannels. The DIC contrast was enhanced according to the order of round-, square-, and rectangle-type microchannels. The velocity of the single living cell was consistently increased with increasing electric field strength and pH. However, the velocity of cell was decreased with increasing run buffer concentration. The driving direction of the individual single cell was simply controlled by changing the polarity of the applied voltage and the electric field strength. The cells were consistently manipulated in the microchannel under the co-application of the low electric field of 2.44 V/cm, instead of the solo application of the hydrodynamic force.     

Non-thermal effects of continuous 2.45 GHz microwaves on Fas-induced apoptosis in human Jurkat T-cell line

Non-thermal effects of microwaves (MWs) are one of the main issues studied for revising standards. The effects of MW exposure on apoptosis at non-thermal level (48 h, 2.45 GHz, 5 mW/cm2) have been studied. Results obtained assess non-thermal MW effects on Fas, but neither on butyrate- nor on ceramide-induced apoptosis in human Jurkat T-cell line. These data show that MW interacts either with Fas pathway between receptor and caspase-3 activation or on membrane proteins (i.e. Fas receptor or neurosphyngomyelinase).     

LEAKAGE OF 86Rb+ AFTER ULTRAVIOLET IRRADIATION OF Escherichia coli K-12

Abstract— Stationary phase cultures of a DNA repair proficient Escherichia coli K-12 strain showed a release of intracellular material as assessed by three different methods (260 nm absorption; [methyl-³H]thymidine leakage and ⁸⁶Rb⁺ leakage) after broad-band (Black-Light Blue) near-UV radiation but not after far-UV (254 nm) radiation. As a control response for membrane damage to cells, this leakage of intracellular material was also determined by each method after mild-heat (52°C) treatment of E. coli K-12. An action spectrum for the release of ⁸⁶Rb⁺ from E. coli K-12 after irradiation with monochromatic wavelengths, from 254 to 405 nm, is also presented. The action spectrum for lethality (F₃₇ values) obtained for this strain, shows that leakage of ⁸⁶Rb⁺ occurs at fluences equivalent to or slightly less than fluences causing inactivation at wavelengths above 305 nm. In contrast, at wavelengths below 305 nm, leakage of ⁸⁶Rb⁺ from irradiated cells can be induced but only at fluences significantly greater than was required to cause cell inactivation. These results indicate, therefore, that near-UV radiation can induce a damaging effect on the cell's permeability barrier which may be significant in causing the death of the cell, whereas the effect is not significant in causing the death of cells by far-UV radiation where DNA damage is known to be the main cause of lethality.     

Two-photon photodynamic therapy of C6 cells by means of 5-aminolevulinic acid induced protoporphyrin IX

Photodynamic therapy (PDT) has received increased attention as a treatment modality for malignant tumors as well as non-oncologic diseases such as age-related macular degeneration (AMD). An alternative to excite the photosensitizer by the common one-photon absorption is the method of two-photon excitation (TPE). This two-photon photodynamic therapy has the potential of improving the therapeutic outcome due to a highly localized photodynamic effect. The present study investigated the two-photon excited PDT performing in vitro experiments where C6 rat glioma cells were irradiated with a pulsed and focused fs Ti:sapphire laser emitting light at 800 nm. The irradiance distribution of the laser beam was carefully analyzed before the experiment and the applied irradiance was known for each position within the irradiated cell layer. Cells were divided into four groups and one group was incubated with 5-ALA and irradiated 4-5h later. The survival of this group was tested after irradiation by means of ethidium bromide and acridine orange staining and compared to a control group, which was irradiated under the same conditions, but not incubated with 5-ALA before. Both groups showed necrotic areas depending on the applied irradiance, the value of which at the margin of the necrotic area could be deduced from its size. 5-ALA incubated cells became necrotic after irradiation with a mean irradiance above 6.1 x 10(10) W/cm(2), while non-incubated cells remained viable. Cells of both groups became necrotic when treated with an irradiance above 10.9 x 10(10) W/cm(2). The observed affected area of the cell layers was between 0.13 mm(2) and 1.10 mm(2). Since the irradiation of non-incubated cells below the mean power density of 10.9 x 10(10) W/cm(2) induced no necrosis, apparently no thermal damage was induced in the cells and necrosis of the 5-ALA incubated cells can be ascribed to the photodynamic effect induced by two-photon excitation. The successful photodynamic treatment of a large area of a monolayer cell culture induced by two-photon excitation offers new perspectives for photodynamic treatment modalities.