Change in the percent of lactate dehydrogenase isoenzyme level in testes of animals exposed to superhigh frequency radiation

The content of six lactate dehydrogenase isoenzymes in testes of rats exposed to electromagnetic field of 3-cm wavelength range was studied. The changes in their percent contents were found to be inhomogeneous compared with control. It is assumed that electromagnetic radiation affects the organs of the human urinogenital system. The results can be used for estimating the safety of persons professionally exposed to electromagnetic radiation of the industrial frequency range and in the therapy of diseases of the urinogenital system.     

Reflectionless passage of an electromagnetic wave through an inhomogeneous plasma layer

An exactly solvable model is used as a basis to study the reflectionless passage of a transverse electromagnetic wave through an inhomogeneous plasma containing large-amplitude, small-scale (subwave-length) structures (in particular, opaque regions) that cannot be correctly described by approximate methods. It is shown that, during the reflectionless passage of an electromagnetic wave, strong wave field splashes can occur in certain plasma sublayers. The nonuniform spatial plasma density profile is characterized by a number of free parameters describing the modulation depth of the dielectric function, the characteristic sizes of the structures and their number, the thickness of the inhomogeneous plasma region, and so on. Such plasma density structures are shown to be very diverse when, e.g., a wave that is incident from vacuum propagates without reflection through a plasma layer (wave barrier transillumination). With the cubic nonlinearity taken into account, a one-dimensional problem of the nonlinear transillumination of an inhomogeneous plasma can be solved exactly.     

Heterogeneity of Protein Substates Visualized by Spin-label EPR

The energy landscape of proteins is characterized by a hierarchy of substates, which give rise to conformational heterogeneity at low temperatures. In multiply spin-labeled membranous Na,K-ATPase, this heterogeneous population of conformations is manifest by strong inhomogeneous broadening of the electron paramagnetic resonance (EPR) line shapes and nonexponential spin-echo decays, which undergo a transition to homogeneous broadening and exponential relaxation at higher temperatures (previous study). In this study, we apply these EPR methods to small water-soluble proteins, of the type for which the existence of conformational substates is well established. Both α-helical and β-sheet aqueous proteins that are spin-labeled on a single cysteine residue display spin-echo decays with a single phase-memory time T_2M and conventional EPR line shapes with predominantly homogeneous broadening, over a broad range of temperatures from 77 K to ∼ 250 K or higher. Above ∼ 200 K, the residual inhomogeneous broadening is reduced almost to zero. In contrast, both the proteins and the spin label alone, when in a glycerol-water mixture below the glass transition, display heterogeneity in spin-echo phase-memory time and a stronger inhomogeneous broadening of the conventional line shapes, similar to multiply spin-labeled membranous Na,K-ATPase below 200 K. Above 200 K (or the glass transition), a single phase-memory time and predominantly homogeneous broadening are found in both spin-label systems. The results are discussed in terms of solvent-mediated protein transitions, the ability of single spin-label sites to detect conformational heterogeneity, and the desirability of exploring multiple sites for proteins with the size and complexity of the Na,K-ATPase.     

Heterogeneity of Protein Substates Visualized by Spin-label EPR

The energy landscape of proteins is characterized by a hierarchy of substates, which give rise to conformational heterogeneity at low temperatures. In multiply spin-labeled membranous Na,K-ATPase, this heterogeneous population of conformations is manifest by strong inhomogeneous broadening of the electron paramagnetic resonance (EPR) line shapes and nonexponential spin-echo decays, which undergo a transition to homogeneous broadening and exponential relaxation at higher temperatures (previous study). In this study, we apply these EPR methods to small water-soluble proteins, of the type for which the existence of conformational substates is well established. Both α-helical and β-sheet aqueous proteins that are spin-labeled on a single cysteine residue display spin-echo decays with a single phase-memory time T_2M and conventional EPR line shapes with predominantly homogeneous broadening, over a broad range of temperatures from 77 K to ∼ 250 K or higher. Above ∼ 200 K, the residual inhomogeneous broadening is reduced almost to zero. In contrast, both the proteins and the spin label alone, when in a glycerol-water mixture below the glass transition, display heterogeneity in spin-echo phase-memory time and a stronger inhomogeneous broadening of the conventional line shapes, similar to multiply spin-labeled membranous Na,K-ATPase below 200 K. Above 200 K (or the glass transition), a single phase-memory time and predominantly homogeneous broadening are found in both spin-label systems. The results are discussed in terms of solvent-mediated protein transitions, the ability of single spin-label sites to detect conformational heterogeneity, and the desirability of exploring multiple sites for proteins with the size and complexity of the Na,K-ATPase.     

Effect of a weak electromagnetic field on the rate of hydrogen peroxide production in aqueous solutions

A theoretical model of the mechanism of action of weak electromagnetic fields on water solutions has been constructed. The model predicts the redistribution of protons on spatial inhomogeneities in water medium. It is shown that an external field leads to the phasing of ions on the standing wave, which is considered as an inhomogeneity. As a result of an inhomogeneous distribution of hydrogen ions, local regions with a higher and lower acidity arise. The acidity of medium substantially affects the rate of chemical reactions; therefore, the exposure to a weak external field can change this parameter. The effect of local changes in acidity on the rate of hydrogen peroxide production was considered. It was predicted that the exposure to a weak electromagnetic field with particular parameters can increase the rate and, as a consequence, the concentration of hydrogen peroxide in solution.     

Instability of a magnetic drift wave in the vicinity of the dust-ion hybrid resonance

Low-frequency electromagnetic waves propagating perpendicular to the gradients of the density and magnetic field in an inhomogeneous dusty plasma whose mass density is determined primarily by the dust component are analyzed. It is shown that, in analyzing the dispersion properties of inhomogeneous plasma, it is important to take into account the dynamic properties of ions in the vicinity of the dust-ion hybrid resonance. The conditions for the onset of instability of a magnetic drift wave are investigated for different relations between parameters of the inhomogeneity and the value of the Alfvén velocity. The differences from the previous results, as well as possible astrophysical applications, are discussed.     

A Novel Detection Scheme for High-Resolution Two-Dimensional Spin-Echo Correlated Spectra in Inhomogeneous Fields

Background

Two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy is a powerful and non-invasive tool for the analysis of molecular structures, conformations, and dynamics. However, the inhomogeneity of magnetic fields experienced by samples will destroy spectral information and hinder spectral analysis. In this study, a new pulse sequence is proposed based on the modulation of distant dipolar field to recover high-resolution 2D spin-echo correlated spectroscopy (SECSY) from inhomogeneous fields.

Method and Material

By using the new sequence, the correlation information between coupled spins and the J coupled information with straightforward multiplet patterns can be obtained free from inhomogeneous line broadening. In addition, the new sequence is also suitable for non-J coupled spin systems. Although three-dimensional acquisition is needed, the evolution of indirect detection dimensions is carefully designed and the ultrafast acquisition scheme is utilized to improve the acquisition efficiency. A chemical solution of butyl methacrylate (C₈H₁₄O₂) in DMSO (C₂H₆SO) in a deshimmed magnetic field was tested to demonstrate the implementation details of the new sequence. The performance of the new sequence relative to the conventional SECSY sequence was shown by using an aqueous solution of main brain metabolites in a deshimmed magnetic field.

Conclusion

The results reveal that the new sequence provides an attractive way to eliminate the inhomogeneous spectral line broadening for the spin-echo correlated spectrum and is a promising tool for the study of metabolites in metabonomics, even for the applications on in vivo and in situ high-resolution 2D NMR spectroscopy.     

人体电磁兼容系统与电磁场处理水--Ⅲ.电磁水对人体电磁场的作用

《人体电磁兼容系统与电磁场处理水》一文分三篇写。第一篇“Ⅰ.人体电磁兼容系统”,讨论了人体体内电磁场;第二篇“Ⅱ·电磁水的特性”,讨论了电磁水的电磁场。二文均已发表于《生物磁学》。本文是第三篇,讨论电磁水电磁场对人体电磁场的作用,重点阐明饮用电磁水后,主要是电磁水的电磁场作为入射场与体内场发生迭加作用,产生耦合电磁场,从而实现其对体内场的调节作用,达到维系身体健康的目的。由于有关水的问题非常复杂,动态性强,故大多数关于耦合场的研究均服从于“统计学规律”。     

藻胆素的构象变化及其对光吸收的影响

研究藻胆蛋白中藻胆素构象的变化对藻胆素光谱性质的影响,在光合作用原初过程的研究中有重要意义．由于四吡咯发色团构象的非同源性随机涨落,藻胆素的电子激发态能级呈类Boltzmann分布;藻胆素的电子－振动吸收跃迁谱带线型因子可描述为与构象随机分布因子有关的卷积形式;藻胆素构象的随机分布导致电子－振动吸收跃迁谱带的不对称增宽．     

Selective laser spectroscopy of 1-phenylnaphthylamine in phospholipid membranes.

Time-resolved and steady-state spectra and kinetics of anisotropy of 1-phenylnaphthylamine (1-AN) fluorescent probe in phosphatidylcholine bilayer membranes have been examined using a nanosecond laser spectrofluorimeter. In this system we consider two kinds of inhomogeneous broadening of spectra, the first of which is due to different probe locations in membrane, while the second one is due to the statistical distribution of interaction energy within a given location. This broadening causes the red shift of the fluorescence spectrum at red-edge excitation, the specific dependences of instantaneous fluorescence and fluorescence anisotropy spectra on the wavelength of excitation. A field diagram is presented which, by describing the free energy levels of the polar fluorescent probe in membranes, makes it possible to unambiguously interpret the whole set of experimental data. It is suggested that the release of potential energy of intermolecular interactions which occurs in the process of relaxation, results in accelerated (light-induced) rotation of the probe inside the membrane.     

Self-consistent model of a pulsed air discharge excited by surface waves

A complete self-consistent electrodynamic model of a pulsed gas discharge excited by surface waves is developed. The model allows one to calculate both the initial phase of the discharge front propagation and the parameters of the produced plasma. The spatiotemporal evolution of the electromagnetic field and plasma parameters at the discharge front is investigated for the first time. It is shown that discharge propagation is mainly governed by a breakdown wave in an inhomogeneous electric field at the leading edge of the ionization front. It is found that the effect of the electric field enhancement in the plasma resonance region significantly affects the velocity of the breakdown wave. The results of calculations agree well with experimental data.     

Stark effect experiments in cytochrome c-type proteins: structural hierarchies.

We performed hole-burning Stark effect experiments on cytochrome c in which the iron of the herne was either removed or replaced by Zn. According to the experiments, the free-base compound has an effective inversion center, even in the protein. The Zn compound, on the other hand, shows quite peculiar features: in the low-frequency range of the inhomogeneous band, it definitely has a dipole moment, as indicated by a splitting of the hole in the external field. However, in the maximum of the inhomogeneous band, a severe charge redistribution occurs, as the experiments show. In addition to the Stark experiments, we performed calculations of the electrostatic fields at the pyrrole rings and at the metal site of the heme group. We interpret our findings with a model based on structural hierarchies: the protein can exist in a few subconformations, which can be distinguished through the structure of the heme pocket. The different pocket structures support different structures of the chromophore, which, in turn, can be distinguished through their behavior in an external field. These distinct structures, in turn, correspond to a rather broad distribution of protein structures, which leave, however, the pocket structure largely unchanged. These structures show up in inhomogeneous broadening.     

Model of detergent-induced spectral changes of the B800-850 complex from Chromatium minutissimum

The absorption and circular dichroism spectra of the B800-850 complex from Chromatium minutissimum before and after the Triton X-100 treatment were simulated by means of standard exciton theory, taking into account inhomogeneous broadening. To explain the spectral changes of the B800-850 complex treated with Triton X-100, we have assumed that all bacteriochlorophyll pigments absorbing at 850 nm exhibit the same additional rotation of approximately 20 degrees around the axis perpendicular to the membrane plane. This has been sufficient to fit the transformation in absorption and circular dichroism spectra induced by detergent treatment of the B800-850 complex.     

Effect of a low-frequencey magnetic field on esterase activity and change in pH in wheat germ during swelling of wehat seeds

The role of nonsteady phenomena determined by a low velocity of ion movements in a weak external field is considered in relation to their possible nonlinear effects on processes occurring in boundary layers near the membrane, particularly, on the release of membrane-bound proteins and pH value. It is shown that a short-term treatment of wheat seeds with low-frequency magnetic field at the stage of esterase activation during seed swelling enhances the activation of esterases; the effect observed at final stages of activation depends on the time after the treatment with electromagnetic field. Treatment of seeds with electromagnetic field at this stage changed qualitatively the time course of the release of reaction products into the medium: the reaction rate increased initially and then decreased below the control level. At earlier stages of swelling in treated seeds and at all stages in control seeds, the time course of the product release was linear. The retardation of the release of the reaction products at terminal stages of esterase activation is presumably related to the release of proteins and their complexes under the action of electromagnetic field and the resulting restoration of the barrier properties of membranes. Treatment with electromagnetic field also caused a noticeable acceleration of proton flow form the medium, which was judged from pH changes in the bulk medium and in the vicinity of germ surface. The difference between the treated and control samples after 23-24 h of imbibition became statistically significant and was as high as 0.4 pH units. By taking into account the nonsteady phenomena occurring upon action of low-frequency electromagnetic field, it is possible to explain unusual dependences of biological effects on the amplitude of the electromagnetic field, including the atypical enhancement of these effects by the action of weak low-frequency fields.     

Enhancement of docetaxel-treated MCF-7 cell death by 900-MHz radiation

The aim of the study was to investigate the effect of high-frequency electromagnetic field of 900 MHz at 8 W input power on metabolic activity of human breast adenocarcinoma MCF-7 cells. With the aid of the colorimetric MTT assay, it was shown that there is significant change in cell culture survival exposed to docetaxel in field-free conditions in comparison with cells treated with docetaxel simultaneously exposed to high-frequency electromagnetic field.     

Protein Linewidth and Solvent Dynamics in Frozen Solution NMR

Solid-state NMR of proteins in frozen aqueous solution is a potentially powerful technique in structural biology, especially if it is combined with dynamic nuclear polarization signal enhancement strategies. One concern regarding NMR studies of frozen solution protein samples at low temperatures is that they may have poor linewidths, thus preventing high-resolution studies. To learn more about how the solvent shell composition and temperature affects the protein linewidth, we recorded ¹H, ²H, and ¹³C spectra of ubiquitin in frozen water and frozen glycerol-water solutions at different temperatures. We found that the ¹³C protein linewidths generally increase with decreasing temperature. This line broadening was found to be inhomogeneous and independent of proton decoupling. In pure water, we observe an abrupt line broadening with the freezing of the bulk solvent, followed by continuous line broadening at lower temperatures. In frozen glycerol-water, we did not observe an abrupt line broadening and the NMR lines were generally narrower than for pure water at the same temperature. ¹H and ²H measurements characterizing the dynamics of water that is in exchange with the protein showed that the ¹³C line broadening is relatively independent from the arrest of isotropic water motions.     

Molecular Probes: What Is the Range of Their Interaction with the Environment?

We performed pressure-tuning hole-burning experiments on a modified cytochrome c protein in a glycerol/buffer glass. The shift and the broadening of the holes were investigated for various frequencies within the inhomogeneous band. On the basis of a simple model, we were able to estimate the interaction range between chromophore and protein. It is ~4.5 Å. The parameters that enter the model are the compressibility, the static mean-square displacement, the inhomogeneous width, and the average spectral shift per pressure. From this result and from our experiments on pressure-induced denaturing, we conclude that water molecules have to be brought very close to the chromophore during the denaturation process.     

A multivariate approach to the treatment of peripheral nerve transection injury: the role of electromagnetic field therapy

A multivariate approach to the treatment of peripheral nerve transection injury has been used in a rat model. A pilot study (48 animals, 8 groups) examined variables associated with the method and timing of surgical repair, the arrest of wallerian degeneration, and the role of pulsing electromagnetic field therapy (PEMF) in functional recovery. A second phase (90 animals, 6 groups) then studied the timing and duration of pulsing electromagnetic field therapy as the only variable in larger groups of animals. The pilot study revealed that a vein-graft conduit did not improve functional recovery compared with standard epineurial repair. Additionally, delayed repair compared favorably with immediate repair. The use of chlorpromazine to inhibit the toxic effects of calcium influx appeared to enhance early functional recovery, and the combination of delayed nerve repair and pulsing electromagnetic field therapy seemed to consistently improve function. The second phase of the study has demonstrated (for the first time) statistical improvement in ambulation in animals treated with delayed surgical repair and prolonged pulsing electromagnetic field therapy. We postulate that future treatment of nerve transection injuries will involve a combined treatment regimen consisting of the immediate arrest of wallerian degeneration, delayed surgery, and pulsing electromagnetic field therapy.     

Electromagnetic absorption in an inhomogeneous model of man for realistic exposure conditions

The advances made in quantifying electromagnetic absorption and its distribution for various exposure profiles are described. The conditions that have been studied extensively are: free-space irradiation and its variations, such as the presence of ground and reflecting surfaces and other humans in close proximity. Using an inhomogeneous block model of man, work has recently been extended to leakage-type near-fields such as those from RF heat sealers and other electronic equipment. Projections are made for the extension of this work to evaluate coupled near-fields, design of multielement near-field applicators to obtain physician-prescribed uniform or nonuniform rates of regional heating, and for the inverse scattering problem necessary for electromagnetic biomedical imaging. Accurate information about the dielectric properties of various tissues becomes increasingly important for proper inhomogeneous modeling of man.     

Factors restricting diffusion of water-soluble spin labels.

Line broadening of spin label signals is treated in terms of concentration, viscosity, charge and temperature dependencies. Line broadening of spin label signals may be caused either by spin label interactions or by the interaction between a spin label and a second paramagnetic species. Line broadening has been related to collision frequency in the literature and is treated in that way here. Collision frequency is related to diffusion processes in a way that allows information to be obtained about the diffusion environment. Several potential spin label line-broadening agents are compared as to their effectiveness. Small polymer beads with graduated pore sizes are used to show that collisional broadening has a marked dependence on the long-range structure of the diffusion environment. Application of these results to biological diffusion processes is considered.