Effects of pulsed extremely-low-frequency magnetic fields on skin wounds in the rat

Rats with skin-wounds surgically created on their backs were exposed immediately after surgery and every 12 h thereafter to pulsed, extremely-low-frequency magnetic fields. The shape of the pulse was a positive triangle (50 Hz, 8 mT peak). The rate of healing of skin wounds was evaluated macroscopically and by light and electron microscopy at 6, 12, 21, and 42 days after the operation. A significant increase in the rate of wound contraction was found in rats treated with magnetic fields. Forty-two days after surgery all treated animals show fully closed wounds, while control rats at the same time intervals still lacked a final 6% of the wound surface to be covered. Treated rats showed earlier cellular organization, collagen formation and maturation, and a very early appearance of newly formed vascular network.     

Effects of low-amplitude pulsed magnetic fields on cellular ion transport

Pulsed magnetic fields (PMFs) are widely used to treat difficult fractures of bone and other disorders of connective tissue. It is not clear how they interact with tissue metabolism, although it has been proposed that induced currents or electric fields impinging on cell membranes may modify their ion transport function. This hypothesis was tested by treating in vitro models for ion transport processes with short-term exposure to PMFs. No change occurred in active transport of potassium or calcium in human red cells or in calcium transport through an epithelial membrane. We considered less direct action on red cell membranes, that their permeability might be modified after PMF treatment, and also that PMFs might alter the extracellular ionic activity within connective tissue by interacting with its Donnan potential. Each of these studies proved negative, and we conclude that the PMF waveforms used here do not exert a general short-term effect on cellular ion transport.     

Phosphate metabolites in muscular contraction caused by magnetic stimulation

The metabolism of high energy phosphates during muscular contraction due to direct electrical stimulation, indirect stimulation via nerve excitation, and magnetic stimulation was studied in isolated muscles (frog sartorius muscles) by (31)P nuclear magnetic resonance ((31)P-NMR). Twitch amplitudes elicited by each stimulus were measured alternatively at 3 mm displacement loading and 5 g weight. Both the creatine/inorganic phosphate (PCr/Pi) and pH changes were more marked in direct electrical stimulation than in magnetic stimulation. The muscular contraction caused by magnetic stimulation showed less fatigue than that caused by direct electrical muscular stimulation.     

Differential survival of isolated portions of crayfish axons

Summary Electron microscopic studies show that transplanted segments of sensory axons of varying lengths degenerate within 7–14 days whereas transplanted segments of crustacean motor axons survive morphologically intact for 20–30 days. The middle portion of an isolated motor axon segment degenerates less rapidly than portions of the same axon located nearer the periphery or nearer the ventral nerve cord. One week after transplantation, glial cells appear to phagocytize sensory axons whereas glial cells around motor axons appear to hypertrophy and to have more rough endoplasmic reticulum. After three weeks, motor axons also appear to be phagocytized by glial cells.These data suggest that the glia surrounding isolated motor axons can change from a supportive to a destructive function, whereas glial cells surrounding severed sensory axons primarily have a destructive function. These and other data also indicate that crustacean motor axons receive significant trophic inputs from their own perikaryon, from post-synaptic contacts, and from adjacent glial cells. The possibility that adjacent healthy cells may supply metabolically deficient cells with needed substances could be a significant adaptive advantage for the evolution of multicellular organisms.Supported in part by an NIH grant (NS-1186101) to Dr. BittnerThe authors wish to thank Mr. Martis Ballinger and Mr. Robert Riess for their valuable assistance in all stages of this research     

Effects of transcranial magnetic stimulation on oxidative stress in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) reproduces a multiple sclerosis (MS)-like experimental model. The main objective was to evaluate the effect of extremely low-frequency electromagnetic fields (EL-EMF) application, like a paradigm of transcranial magnetic stimulation (TMS) in the development of EAE. Rats were injected with a single dose of 150?μg of myelin oligodendrocyte glycoprotein (MOG, fragment 35–55) to produce experimental MS. To assess the effect of TMS application in EAE, the rats were treated with TMS (60?Hz and 0.7?mT) for 2?h in the morning, once a day, 5 days a week, during 3 weeks. TMS was applied to the head. The effect of TMS on EAE was evaluated as motor symptoms and, oxidative and cell damage. The data showed that MOG induced motor symptoms as tail paralysis and limb paresis/paralysis, oxidative stress and cell death similar to MS when compared with control animals. Importantly, TMS application attenuated motor symptoms, oxidative and cell damage, whereas it increased antioxidant system. Our findings suggest that: (i) MOG reproduces an experimental model of MS characterised by oxidative and cell damage; and (ii) TMS application decreases oxidative stress and cell death induced by MOG.     

Influence of pulsed electromagnetic and pulsed vector magnetic potential field on the growth of tumor cells

Aims and Background: Tumor diseases cause 20% of deaths in Europe and they are the second most common cause of death and morbidity after cardiovascular diseases. Thus, tumor cells are target of many therapeutic strategies and tumor research is focused on searching more efficient and specific drugs as well as new therapeutic approaches. One of the areas of tumor research is an issue of external fields. In our work, we tested influence of a pulsed electromagnetic field (PEMF) and a hypothetic field of the pulsed vector magnetic potential (PVMP) on the growth of tumor cells; and further the possible growth inhibition effect of the PVMP. Methods: Both unipolar and bipolar PEMF fields of 5?mT and PVMP fields of 0?mT at frequencies of 15?Hz, 125?Hz and 625?Hz were tested on cancer cell lines derived from various types of tumors: CEM/C2 (acute lymphoblastic leukemia), SU-DHL-4 (B-cell lymphoma), COLO-320DM (colorectal adenocarcinoma), MDA-BM-468 (breast adenocarcinoma), and ZR-75-1 (ductal carcinoma). Cell morphology was observed, proliferation activity using WST assay was measured and simultaneous proportion of live, early apoptotic and dead cells was detected using flow cytometry. Results: A PEMF of 125?Hz and 625?Hz for 24?h–48?h increased proliferation activity in the 2 types of cancer cell lines used, i.e. COLO-320DM and ZR-75-1. In contrast, any of employed methods did not confirm a significant inhibitory effect of hypothetic PVMP field on tumor cells.     

Unusual neuromuscular junctions in the heart of the crayfish (Procambarus clarkii)

Summary The neuromuscular junctions in the crayfish heart were studied with the electron microscope and were classified into two types based on the characteristics of the post-synaptic side. Type I junction was characterized by a mazy post-synaptic apparatus which has been referred to in this work as the junctional envelope, consisting of the cytoplasmic processes and/or lamellae of the muscle cell. Type II junction on the other hand, lacked the junctional envelope. The nerve terminals in both Type I and Type II junctions contained two types of synaptic vesicles: large granular and small agranular vesicles, which were about 1000 Å and 450 Å in diameter respectively. The physiological significance of these neuromuscular junctions and the nature of their synaptic vesicles are discussed.Acknowledgement. The author wishes to express sincere gratitude to Prof. T.Yamamoto for the kind encouragement and guidance during the course of this study.The presence of this unusual neuromuscular junction, coupled with the histological characteristics of heart muscles themselves (Komuro, 1968), may be involved in the different physiological properties of the crustacean heart. This subject will be discussed in a later publication by the author.     

The effects of Zn2+ on guinea pig isolated heart preparations

Isolated guinea pig hearts were perfused, by the Langendorff technique, with 30, 15, 7.5, and 1.5 μM Zn²⁺ in Chenoweth solution. Contractile force, coronary flow, and heart rate were recorded by means of Narco IV Physiograph. Calcium inhibitor (Verapamil 1 μM) and anion inhibitor (DIDS: 0.1, 1, and 5 μM) were used subsequently in the perfusing solutions in order to distinguish some of the possible mechanisms that Zn²⁺ uses to exert its action on cardiac myocytes. Isomolar to zinc concentration of Pb (II) and Co (II) were used to elucidate whether zinc effects on heart are specific for this metal. All hearts were used to estimate their zinc and calcium content by means of AAS (Atomic Absorption Spectrometry). Our findings suggest that the higher the Zn²⁺ concentration, the more toxic effects on heart are expressed by rapid reversible contractile force reduction and reversible specific changes of heart rate and flow. Zinc 1.5 μM in the perfusing solution benefits heart performance, but not significantly. Furthermore, the metal exerts specific effects on guinea pig heart, and it is rather possible that these effects on cardiac myocytes are held through cell membrane receptors.     

Therapeutic staff exposure to magnetic field pulses during TMS/rTMS treatments

Transcranial magnetic stimulation or repetitive transcranial magnetic stimulation (TMS/rTMS) is currently being used in treatments of the central nervous system diseases, for instance, depressive states. The principles of localized magnetic stimulation are summarized and the risk and level of occupational field exposure of the therapeutic staff is analyzed with reference to ICNIRP guidelines for pulses below 100 kHz. Measurements and analysis of the occupational exposure to magnetic fields of the staff working with TMS/rTMS are presented.     

小龙虾肠道产木聚糖酶细菌的分离与鉴定

【背景】小龙虾肠道微生物是小龙虾降解纤维素和半纤维素的主要驱动力。【目的】研究肠道内细菌的相对丰度,为揭示肠道微生物在小龙虾纤维素降解过程中的作用提供理论支撑。【方法】采用纯培养法从小龙虾肠道筛选产木聚糖酶细菌,并且对小龙虾肠道细菌进行16S高通量测序。【结果】形态学和16SrRNA基因分子鉴定表明,筛选到的4株产木聚糖酶细菌均属于芽孢杆菌科芽孢杆菌属;结合进一步的生理生化特征鉴定,结果为:菌株Z-3为枯草芽孢杆菌(Bacillus subtilis),菌株Z-4为贝莱斯芽孢杆菌(Bacillus velezensis),菌株Z-29为蜡状芽孢杆菌(Bacillus cereus),菌株Z-30为高地芽孢杆菌(Bacillus altitudinis);16S rRNA基因高通量测序结果表明:在属水平上,小龙虾肠道细菌主要是Candidatus Bacilloplasma、拟杆菌属、弧菌属、不动杆菌属、Dysgonomonas、Tyzzerella3、气单胞菌属和希瓦氏菌属细菌。【结论】小龙虾肠道内细菌资源丰富,且芽孢杆菌属细菌在木质纤维素降解过程中发挥一定功能。     

Neurobiological effects of pulsed magnetic field on diabetes‐induced neuropathy

In the clinic, although several pharmacological agents or surgical procedures are used to treat diabetes and diabetes‐induced neuropathic pain, their success has been limited. Therefore, development of different alternatives in treatments is very important. The purpose of this study was to determine the efficacy of pulsed magnetic field (PMF) in improving signs and symptoms of diabetic neuropathy. In this study, the effects of PMF treatment were investigated in Streptozotocin (STZ)‐induced acute and chronic diabetic rats by measuring the thermal latencies, mechanical thresholds, whole blood glucose levels and body weights. After STZ administration to rats, blood glucose level elevated and body weight decreased. Although PMF treatment did not affect changes in body weight, the blood glucose levels of PMF‐treated diabetic rats exhibited a decrease during the treatments. Diabetic animals displayed marked decrease in mechanical thresholds and thermal latencies. While treatment of PMF partially restored the mechanical thresholds and thermal latency in acute diabetic rats, PMF caused a corrective effect on only mechanical threshold of chronic diabetic rats. These results suggested that treatment of PMF can potentially ameliorate the painful symptoms of diabetes, such as hyperalgesia and allodynia, by partially preventing the hyperglycemia. Bioelectromagnetics 31:39–47, 2010. © 2009 Wiley‐Liss, Inc.     

Electrocardiographic alterations induced by zinc ions on isolated guinea pig heart preparations

On guinea pig isolated hearts perfused according to the Langendorff technique, by Chenoweth's solution, and by various concentration of ZnCl₂, surface E.C.G. was recorded for 65 min, after the equilibration period. Concentrations of zinc corresponding to plasma free and exchangable fractions (1.5 μM) exerted only a nonstatistically significant sinus bradycardia. Bradycardia was prominent between the 25th and 35th min of perfusion, with higher concentrations of zinc (7.5 and 15 μM). In even higher (toxic) concentrations of zinc (30 μM), various types of arrhythmias were recorded, such as first degree AV block, idioventricular rhythms, atrial, and ventricular extrasystoles, and asystolia, evoked since the 15th min of perfusion. The above-mentioned findings in relation to low plasma zinc concentrations found in coronary patients and experimental myocardial infarction as well as myocardial injury related to metal fume fever, brought our attention to the involvement of this divalent cation to cardiac physiology and pathophysiology.     

重复经颅磁刺激联合低剂量氟西汀对CUMS抑郁小鼠的影响*

目的:探讨重复经颅磁刺激(rTMS)联合低剂量氟西汀对慢性不可预知轻度压力(CUMS)抑郁小鼠的影响及其交互作用。方法:取42只雄性BALB/c小鼠随机分为正常对照组(Control,7只)和抑郁症模型组(Model,35只),Model组小鼠给予限制塑料管内、鼠笼倾斜、不筑巢、拥挤环境、明暗颠倒、白噪声等6种刺激,每种刺激随机且不同时出现2次,共刺激4周建立CUMS模型。随后35只Model组鼠随机分为CUMS组(8只)、氟西汀组(Fluoxetine,9只)、rTMS组(9只)和rTMS+Fluoxetine组(9只)。Fluoxetine组给予腹腔注射氟西汀5 mg/(kg·d),rTMS组给予10 Hz频率刺激,rTMS+Fluoxetine组给予腹腔注射氟西汀5 mg/(kg·d)和10 Hz频率刺激,Control和CUMS模型组给予相同体积生理盐水腹腔注射和伪刺激,各组均连续干预4周,随后进行行为学实验,最后运用析因设计方差分析方法分析Fluoxetine与rTMS的交互作用。结果:与Control组比,CUMS组小鼠强迫游泳实验中不动时间显著升高(P＜0.05),蔗糖实验中糖喜好程度、旷场实验中心运动次数和体重变化率均显著下降(P＜0.05)。与CUMS组比,rTMS组、Fluoxetine组和rTMS+Fluoxetine组抑郁症小鼠强迫游泳实验中不动时间显著降低(P＜0.01)、蔗糖实验中糖喜好程度和旷场实验中心运动次数显著升高(P＜0.05),其中rTMS+Fluoxetine组联合应用效果更显著(P＜0.05),但体重变化率仅rTMS+Fluoxetine组有变化(P＜0.05)。结论:重复经颅磁刺激和/或氟西汀均能不同程度的改善CUMS小鼠抑郁状态,其中联合应用的干预作用优于单独使用氟西汀或rTMS的效果,且有交互作用。     

低频脉冲磁场对大鼠心肌微血管内皮细胞迁移和NO分泌能力的影响

目的:研究在固定时间和频率下,矩形波形低频脉冲磁场(LF-PMF)对大鼠心肌微血管内皮细胞(CMECs)迁移和NO分泌能力的影响。方法:实验分为4组(对照组,1.0MT组,1.4MT组,1.8MT组)。对照组不加磁场干预,其余各组分别在频率为15Hz,磁场强度分别为1.0MT、1.4MT和1.8MT,时间为4h/d,连续照射3d的条件下,用三角波形作用离体培养的大鼠CMECs。利用transwell检测细胞迁移能力,硝酸还原酶法检测CMECs培养液中NO含量的变化。结果:1.0MT组,1.4MT组和1.8MT组LF-PMF迁移能力与对照组相比均有不同程度提高[(24.40±5.12)(个/视野)vs(22.00±3.87)(个/视野),P<0.05;(31.40±3.81)(个/视野)vs(22.00±3.87)(个/视野),P<0.05;(37.40±4.01)(个/视野)vs(22.00±3.87)(个/视野),P<0.01]。1.0MT组,1.4MT组和1.8MT组LF-PMF的NO分泌能力与对照组相比均有提高[(25.26±1.06)(μmol/L)vs(19.18±2.88)(μmol/L),P<0...     

Cardiac pump function of the isolated rat heart at two modes of energy deprivation and effect of adrenergic stimulation

The contractile function of the isolated rat heart and high energy phosphate content were evaluated under conditions of depressed energy supply caused by disturbances either in mitochondrial ATP production or ATP-phosphocreatine transformation. Amytal (0.3 mM), an inhibitor of mitochondrial respiration, or iodoacetamide (IAA, 0.1 mM) reducing in this dose creatine kinase activity to 19% of the initial level, were used, respectively. Myocardial ATP content remained unaffected in both groups and PCr content decreased to 37% only in amytal-treated group. Very similar alterations in cardiac pump function during volume load were observed in both treated groups; maximal cardiac output was significantly less by 30%, cardiac pressure-volume work by 38–40%, left ventricular (LV) systolic pressure by 24–29%, and LV +dP/dt by 36–39%. In contrast, the extent of decreased LV distensibility was different, a curve relating LV filling volume and end-diastolic pressure was shifted up and to the left much more prominently after IAA treatment. Heart rate was decreased by 24% only in amytal-treated group. Results indicate that a decreased myocardial distensibility is a dominating feature in the acute cardiac pump failure caused by an inhibition of myocardial creatine kinase. Isoproterenol (0.1 M) substantially increased heart rate and pressure-rate product in IAA-treated hearts but failed to increase cardiac work probably due to its inability to improve myocardial distensibility.     

Effects of pulsed magnetic field on the formation of magnetosomes in the Magnetospirillum sp. strain AMB‐1

Magnetotactic bacteria are a diverse group of microorganisms which possess one or more chains of magnetosomes and are endowed with the ability to use geomagnetic fields for direction sensing, thus providing a simple and excellent model for the study of magnetite‐based magnetoreception. In this study, a 50 Hz, 2 mT pulsed magnetic field (PMF) was applied to study the effects on the formation of magnetosomes in Magnetospirillum sp. strain AMB‐1. The results showed that the cellular magnetism (R_mag) of AMB‐1 culture significantly increased while the growth of cells remained unaffected after exposure. The number of magnetic particles per cell was enhanced by about 15% and slightly increased ratios of magnetic particles of superparamagnetic property (size <20 nm) and mature magnetosomes (size >50 nm) were observed after exposure to PMF. In addition, the intracellular iron accumulation slightly increased after PMF exposure. Therefore, it was concluded that 50 Hz, 2 mT PMF enhances the formation of magnetosomes in Magnetospirillum sp. strain AMB‐1. Our results suggested that lower strength of PMF has no significant effects on the bacterial cell morphologies but could affect crystallization process of magnetosomes to some extent. Bioelectromagnetics 31:246–251, 2010. © 2009 Wiley‐Liss, Inc.     

Transcranial magnetic stimulation as an antioxidant

In the last decades, different transcranial magnetic stimulation protocols have been developed as a therapeutic tool against neurodegenerative and psychiatric diseases, although the biochemical, molecular and cellular mechanisms underlying these effects are not well known. Recent data show that those magnetic stimulation protocols showing beneficial effects could trigger an anti-oxidant action that would favour, at least partially, their therapeutic effect. We have aimed to review the molecular effects related to oxidative damage induced by this therapeutic strategy, as well as from them addressing a broader definition of the anti-oxidant concept.     

Clodronate changes neurobiological effects of pulsed magnetic field on diabetic rats with peripheral neuropathy

Several studies have reported that pulsed magnetic fields (PMFs) can be a choice of therapy for diabetic peripheral neuropathy. However, the exact underlying mechanism of PMF is still not known. The purpose of this study was, therefore, to investigate the effects of clodronate encapsulated with liposome, a specific agent depleting macrophage, on PMF-treated streptozotocin-induced type I diabetic rats with peripheral neuropathy. Effects of PMF, liposome-encapsulated clodronate (LEC) or their combined treatments were investigated in diabetic rats by measuring the thermal latencies, mechanical thresholds, whole blood glucose levels, serum insulin level, and body mass. In diabetic rats, PMF exhibited a decrease in the blood glucose levels but did not change the serum insulin level. Both mechanical thresholds and thermal latencies of diabetic rats enhanced throughout the PMF treatment. During the PMF treatment, the administration of LEC suppressed the PMF-induced decrease in blood glucose level, PMF-induced increase in mechanical threshold and thermal latencies in diabetic animals. In addition, PMF reduced the LEC-induced increase in insulin levels of diabetic rats. Findings demonstrated that although effects of both PMF alone and LEC alone on diabetic animals are mostly positive, LEC may remove the therapeutic efficacies of PMF in combined treatment.     

电刺激迷走神经对蟾蜍心率和心率变异的影响

目的:观察不同频率迷走神经刺激对蟾蜍离体心脏的心率及心率变异的影响。方法:将蟾蜍心脏和右侧迷走交感干离体后,以不同频率电刺激神经,记录心电图曲线并作心率变异性(HRV)分析。结果:交感神经阻断后,电刺激迷走交感干,心率(HR)显著下降(P0.01),全部正常心动周期的标准差(SDNN)和相邻正常心动周期差值的均方根(RMSSD)显著升高(P0.01),不同频率刺激组之间没有明显差异;与对照组相比,各指标变化较大;给药组0.2Hz时高频(HF)显著升高(P0.01),低频/高频比值(LF/HF)明显降低(P0.05),0.8Hz时HF和LF/HF接近刺激前水平。结论:一定范围内增加刺激频率,迷走神经降低心率的作用增强;没有交感神经调节条件下的迷走神经对心率和心率变异的调节可能存在不同的机制。