Decreased Production of the Superoxide Anion Radical in Neutrophils Exposed to a Near-Null Magnetic Field

Biophysics - This paper reports that pre-incubation of a neutrophil suspension in the presence of a near-null magnetic field produced using a system of magnetic shields (a residual constant...     

Early Sprouting and First Stages of Growth of Rice Seeds Exposed to a Magnetic Field

The effects of a stationary magnetic field on the germination of rice seeds (Oryza sativa, L.) and on the initial stages of growth of rice plants have been evaluated. In both tests, the seeds were exposed to one of two magnetic field strengths (125 or 250 mT) for different times (1 min, 10 min, 20 min, 1 h, 24 h, or chronic exposure) as 12 separate treatments (doses D1–D6 for 125 mT and doses D7–D12 for 250 mT). Nonexposed seeds were used as controls (C). The mean germination time (MGT) was significantly reduced compared to control when seeds were exposed to magnetic field (54.00 h for D5 and D11, and 58.56 h for control). The parameters T₁ and T₁₀, times required to obtain 1 and 10% of germinated seeds, were also reduced. The T₁₀ of control seeds was 44.40 h, while treatments D5, D6, D11, and D12 gave rise to values of 36.00, 36.96, 32.64, and 39.36 h, respectively. The higher germination rate of treated seeds obtained in the germination test is in agreement with the higher lengths and weights of rice plants exposed to a magnetic field recorded on the growth tests. All the parameters measured were over the control ones, although the highest lengths and weights of rice plants were obtained for chronic exposure to magnetic field (doses D6 and D12). Stem length of control plants (45.36 mm) measured at the tenth day was significantly lower than that obtained for doses D6 (58.58 mm) and D12 (80.63 mm); the same behavior was observed on total length, stem weight, and total weight. Our finding indicates that this type of magnetic treatment clearly affects germination and the first stages of growth of rice plants.     

Effect of the Magnetic Field on the Characteristics of a Pulsed Penning Ion Source

Plasma Physics Reports - For a Penning ion generator, the dependences of the amplitude–time characteristics of the discharge current and the extracted current on the intensity and...     

The Peculiar Features of Cognitive Processes in Rats Exposed to a Hypomagnetic Field Using Moderate Magnetic Shielding

Biophysics - This paper is focused on the dynamics of the formation of conditioned responses in rats that experienced 14-day moderate magnetic shielding and were placed into a shelter setup when...     

磁场处理种子后番茄幼苗在低温胁迫下保护酶的变化

试验用场强为１０００ＧＳ、１４００ＧＳ、１８００ＧＳ的磁场处理番茄（ＬｙｃｏｐｅｒｓｉｃｏｎｅｓｃｕｌｅｎｔｕｍＭｉｌ）种子,于子叶期和真叶期进行低温胁迫,发现处理组超氧化物岐化酶（ＳＯＤ）比活性和过氧化氢酶（ＣＡＴ）活性均高于对照组。子叶期幼苗谷胱甘肽（ＧＳＨ）和可溶性蛋白含量与对照相比均有所升高。幼苗外观寒害症状也较轻。因此,可以认为磁场处理在一定程度上可提高番茄幼苗的抗寒性。     

Static Magnetic Field Effects on Sinocarotid Baroreceptors in Rabbits Exposed under Conscious Conditions

This research is an extension of our previous studies, where we showed that sinocarotid baroreceptors react to a static magnetic field (SMF) in unconscious rabbits (1–7).

The objective was to study the cardiovascular effect of SMF on sinocarotid baroreceptors in conscious rabbits. Two groups of experiments with different protocols were carried out in 18 healthy adult male rabbits. The first group included 31 experimental runs. In this group 0.24 T static bar magnets were positioned under rabbits' carotid sinus areas for 30 min. The second group included 20 experimental runs. In this group 0.5 T static bar magnets were positioned under carotid sinus areas for 40 min. We found that SMF significantly decreased blood pressure and heart rate and increased blood pressure variability and microcirculation during its local application to the sinocarotid baroreceptor region. SMF might stabilize cellular membranes, leading to an increase of buffer capacity of the sinocarotid baroreceptors to blood pressure variations.     

Changes in Superoxide Dismutase Activity and Peroxynitrite Content in Rat Peritoneal Macrophages Exposed to He-Ne Laser Radiation

The formation of reactive oxygen and nitrogen species by rat peritoneal macrophages induced by a low-intensity He-Ne laser radiation (LR) was studied in this work. It was found that the formation of reactive oxygen species, nitric oxide, and peroxynitrite as well as changes in the activity of superoxide dismutase (SOD) depended to a large extent on the LR dose. In particular, it was found that activation of SOD at low LR doses was accompanied by nitric oxide level increase, while the level of peroxynitrite showed no significant changes. On the other hand, an enhanced LR dose inhibited the enzyme, and this was accompanied by peroxynitrite accumulation. All the measurements were carried out the day after LR treatment. The revealed regularities consequently demonstrate the existence of a deferred LR action on macrophages associated with the production of reactive oxygen and nitrogen species.     

Heart Rate in Rats Exposed to Constant Magnetic Fields

The heart rate in rats exposed to a constant magnetic field 30 min a day for 14 successive days was examined. The animals were fixed between the poles of an electromagnet producing a DC field vertically oriented in the region of the animal's head and spine. The electrocardiogram of each animal was taken during the exposure and during the next 60 min. The heart rate was calculated every 3 min. It was found that a DC magnetic field of relatively high intensity (0.7 T) significantly increased the heart beat in the experimental animals compared to controls.     

Structural Changes in Radish Seedlings Exposed to Cadmium

Radish (Raphanus sativus L. cv. Redondo Vermelho) seedlings were analysed by light and scanning electron microscopy to characterize the structural changes caused by the exposure to 0.5 or 1.0 mM cadmium chloride for 24, 48 and 72 h. The analyses showed changes in the anatomical and morphological characteristics of roots, stems and leaves of two-week-old seedlings. In all tissues, pressure potential was decreased. Premature death with the disintegration of the epidermis and an increase in the number of root hairs was observed in roots exposed to Cd. The stem of seedlings exposed to Cd exhibited more cells layers in the cambial region. The main effects observed in leaves in response to Cd were stomatal closure, lack of cell wall thickening and alterations in the shape of the chloroplasts. It is suggested that the structural changes observed in seedlings treated with Cd were mainly caused by a Cd-induced decrease in water uptake.     

Activity of Lipase and Chitinase Immobilized on Superparamagnetic Particles in a Rotational Magnetic Field

We immobilize hydrolases such as lipase and chitinase on superparamagnetic particles, which are subjected to a rotational magnetic field, and measure the activities of the enzymes. We find that the activities of lipase and chitinase increase in the rotational magnetic field compared to those in the absence of a magnetic field and reach maximum at certain frequencies. The present methodology may well be utilized for the design and development of efficient micro reactors and micro total analysis systems (μ-TASs).     

Changes in Bioelectric Activity in the Human Retina after Transcranial Magnetic Stimulation

The human electroretinogram (ERG) was recorded before and after transcranial magnetic stimulation (TMS) in the region of the cortical link of the visual analyzer. TMS at the frequency of 5 Hz in the projection of the cortical link of the visual analyzer significantly increased the amplitude of the ERG b wave; this was most likely associated with changes in the state of neurons of the central links of the visual analyzer, which enter the retina with efferent fibers of the optic nerve and are actively involved in lateral inhibition.     

超低频脉冲磁场诱导癌细胞凋亡机理研究

我们研究超低频脉冲磁场(峰值0.6~2.0T,梯度10~100T.m-1,脉冲宽度20~200ms,重复频率0.16~1.34HZ)作用于鼠S-180肉瘤。在电镜下观察到肉瘤细胞程序性死亡的许多特征。这一磁场引起约1.5mv的跨膜电位变化,导致钙离子Ca2+内流,促使癌细胞凋亡。磁场对运动电荷的洛仑兹力使运动的带电粒子束缚在拉莫尔(Larmor)半径以内,影响正负带电离子对细胞膜和核膜的渗透能力,甚至在膜上形成空洞。     

Static Magnetic Field Influence on the Activity of some Respiratory Enzymes in Wheat

Most of the published studies on magnetic field action on biological systems have examined reactions in animals, while a smaller number of studies have reported magnetic field effects in plants. The effects of static magnetic field on the activity of several key enzymes in plant metabolism, such as malate dehydrogenase, succinate oxidase, succinate dehydrogenase, and cytochrome oxidase in young wheat seedlings, have been investigated in this study. It appears that the observed changes in enzyme activity could be considered to be a result of the influence of the magnetic field on the reactivity of these enzymes, including effects on metal cations that regulate enzyme activity. The results support the idea of the existence of “biological windows,” particularly with respect to exposure time.     

Behavioral Differences of the Insect Morimus funereus (Coleoptera,Cerambycidae) Exposed to an Extremely Low Frequency Magnetic Field

Changes in the behavior of Morimus funereus individuals were investigated as early manifestations of the contact of a living system with a changed environment primarily established via the nervous system. These experiments were aimed at revealing possible behavioral differences of a laboratory population of cerambycid beetle M. funereus in an “open field” before and after exposure to an extremely low frequency magnetic field (ELF‐MF, 50 Hz, 2 mT). The experimental groups were divided into several activity categories and exposed to ELF‐MF. The results showed that the activity increased in the groups with medium and low motor activity, but decreased in highly active individuals. High individual variability was found in the experimental groups, as well as differences in motor activities between the sexes, both before and after exposure to ELF‐MF. According to preliminary results, we assume the changes of activity in both sexes after exposure to ELF‐MF. The results showed a tendency toward locomotor activity decrease, the affect being more pronounced in females. As opposed to this type of activity, stereotypic activity of males was increased after the exposure, whereas females maintained the expected tendency of decrease. However, we did not obtain statistically significant differences because of a high individual variability and a low total number of individuals in the experiment (N = 28). Only a detailed analysis of the locomotor activity at 1‐min intervals showed some statistically significant differences in behavior between the sexes.     

The Effect of Pulsed Magnetic Field on the Molecular Uptake and Medium Conductivity of Leukemia Cell

The cell membrane acts as a barrier that hinders free entrance of most hydrophilic molecules into the cell. Owing to the numerous applications, the introduction of non-permeate molecules into biologic cells has drawn considerable attention in the past years. The aim of our study was to investigate the effect of time-varying magnetic field on transmembrane molecular transport by measuring bleomycin cytotoxicity and conductivity modifying in K562 cells. The cells were exposed to magnetic pulses of 2.2 T strength peak and about 250-μs duration via Magstim stimulator and double 70-mm coil. Three different frequencies of 0.25, 1, and 10 Hz pulses for 56,112, and 28 numbers of pulses, respectively, were applied (nine experimental groups) and uptake and conductivity was measured in each group. Our results show that time-varying magnetic field increase transmembrane molecular transport and media conductivity; this enhancement is greater for 28 pulses with 1 Hz frequency. The observed uptake enhancement due to magnetic exposure is considerable.     

Neurochemical Changes in Cerebellum of Goldfish Exposed to Various Temperatures

Acclimation of goldfish at 35°C increased the cerebellar content of aspartate, glutamate, and taurine and [³H]glutamate uptake. Acclimation at 4°C increased the levels of glutamine, serine, and alanine and glutamine synthetase (GS) activity. Adenosine content increased in cerebellum of fish acclimated to warm temperature. K⁺-evoked release of endogenous and exogenous glutamate from cerebellar slices increased in fish acclimated at 35°C compared to 4°C. The basal level of cyclic adenosine 3:5-monophosphate (cAMP) in perfused cerebellar slices in fish acclimated at 35°C was much higher than in fish acclimated at 5° and 22°C. It is concluded that variations of environmental temperature produces large neurochemical changes in goldfish cerebellum.     

罗汉果果实总黄酮的含量变化及其抑菌作用

以30％乙醇溶液作提取剂,在超声波功率250W的条件下进行正交试验,结果表明,超声波辅助提取罗汉果果实中总黄酮的最佳条件为料液比1∶9、提取温度80℃、提取时间40 min,在此条件下总黄酮提取率最高,为2.86％.罗汉果果实在10月上旬至12月下旬的生长成熟过程中,总黄酮的含量变化表现为初期逐渐上升,至12月上旬达到最高值,其后快速下降.抑菌实验表明,罗汉果果实中的黄酮类物质对枯草芽胞杆菌、产气杆菌、藤黄八叠球菌和白色念球菌等革兰氏阳性菌的生长具有较显著的抑制作用,而对大肠杆菌、变形杆菌以及青霉和黑曲霉没有抑制作用.     

Exposure to an Extremely-Low-Frequency Magnetic Field Stimulates Adrenal Steroidogenesis via Inhibition of Phosphodiesterase Activity in a Mouse Adrenal Cell Line

Extremely low-frequency magnetic fields (ELF-MFs) are generated by power lines and household electrical devices. In the last several decades, some evidence has shown an association between ELF-MF exposure and depression and/or anxiety in epidemiological and animal studies. The mechanism underlying ELF-MF-induced depression is considered to involve adrenal steroidogenesis, which is triggered by ELF-MF exposure. However, how ELF-MFs stimulate adrenal steroidogenesis is controversial. In the current study, we investigated the effect of ELF-MF exposure on the mouse adrenal cortex-derived Y-1 cell line and the human adrenal cortex-derived H295R cell line to clarify whether the ELF-MF stimulates adrenal steroidogenesis directly. ELF-MF exposure was found to significantly stimulate adrenal steroidogenesis (p < 0.01–0.05) and the expression of adrenal steroid synthetic enzymes (p < 0.05) in Y-1 cells, but the effect was weak in H295R cells. Y-1 cells exposed to an ELF-MF showed significant decreases in phosphodiesterase activity (p < 0.05) and intracellular Ca²⁺ concentration (p < 0.01) and significant increases in intracellular cyclic adenosine monophosphate (cAMP) concentration (p < 0.001–0.05) and cAMP response element-binding protein phosphorylation (p < 0.05). The increase in cAMP was not inhibited by treatment with NF449, an inhibitor of the Gs alpha subunit of G protein. Our results suggest that ELF-MF exposure stimulates adrenal steroidogenesis via an increase in intracellular cAMP caused by the inhibition of phosphodiesterase activity in Y-1 cells. The same mechanism may trigger the increase in adrenal steroid secretion in mice observed in our previous study.