Influence of 2.45 GHz microwave radiation on enzyme activity

Summary The in vitro activity of acetylcholinesterase and creatine phosphokinase was determined during in vitro exposure to 2.45 GHz microwave radiation. The enzyme activities were examined during exposure to microwave radiation at specific absorption rates (SAR) of 1, 10, 50, and 100 mW/g. These specific absorption rates had no effect on the activity of either enzyme when the temperature of the control and exposed samples were similar. These data demonstrate that the activity of these two enzymes is not affected by microwave radiation at the SARs and frequency employed in this study.     

Influence of CW microwave radiation on in vitro release of enzymes from retinol-treated hepatic lysosomes

Hepatic lysosomes were exposed in vitro to microwave radiation (2450 MHz) either prior to or simultaneously with treatment with retinol (vitamin A), and the release of the lysosomal enzymes, β-glucuronidase, acid phosphatase, and cathepsin D, determined. A 60-min microwave exposure (10 or 100 mW/g) of retinol-treated lysosomes had no effect on the amount of release of β-glucuroni-dase, cathepsin D, or acid phosphatase. In addition, 10 and 100 mW/g irradiation of lysosome fractions for 40 min prior to a 20-min retinol and microwave treatment, had no influence on the release of these enzymes. Finally, the effect of microwave radiation on the loss of latency of acid phosphatase and β-glucuronidase from retinol-treated lysosomes was determined. Microwave radiation had no influence on the rate of appearance of these enzymes in the suspending medium. The results indicate that microwave radiation had no effect on the retinol-induced lysosomal enzyme release.     

A circular dichroism study of human erythrocyte ghost proteins during exposure to 2450 MHz microwave radiation

The effect of 2450 MHz microwave radiation on the proteins of human erythrocyte ghosts has been investigated using circular dichroism spectroscopy. A specially constructed waveguide inserted into the spectropolarimeter allowed the continuous recording of optical activity before, during and after microwave irradiation. The data indicate that high levels of microwave radiation (600 mW/g, specific absorption rate) induce decreases in α-helical conformation that may result from both thermal vibrations and increased strain on the intramolecular hydrogen bonds that maintain secondary structure. The latter effect may result from differential intramolecular interactions with the oscillating electric field. Spectrin (bands 1 and 2) isolated from the ghosts was more sensitive to microwave irradiation than intact ghosts, and spectrin-depleted vesicles were the least sensitive. The data, therefore, indicate that the α-helical conformation of spectrin is altered by high levels of microwave radiation.     

Studies on the interaction of microwave radiation with cholinesterase

Summary The significance of the enzyme cholinesterase in studies on the biological effects of microwaves is discussed. Experiments were performed on the direct effect of microwave radiation on the enzyme activity in aqueous solution, and in rabbit blood. Microwave radiation was found to have an effect only when the temperature increase was great enough to denature the enzyme.     

微波处理对人参皂苷生物转化影响的研究

利用微波技术分别对人参皂苷粗品及人参皂苷转化发酵液进行处理,探讨微波处理对人参皂苷生物转化效果的影响。实验结果通过高效液相色谱分析显示,经微波处理后,人参皂苷峰几乎消失,苷元峰突出,表明微波处理对人参皂苷的转化效果显著。并确定微波的最佳处理条件为微波功率30W,辐射60s。     

Effect of microwave radiation on the permeability of carbonic anhydrase loaded unilamellar liposomes

The influence of 2.45 GHz microwave exposure (6 mW/g) on the diffusion processes in enzyme-loaded unilamellar liposomes as bioreactors was studied. The enzyme carbonic anhydrase (CA) was entrapped into cationic unilamellar vesicles. Previous kinetic experiments showed a very low self-diffusion rate of the substrate p-nitrophenyl acetate (PNPA) across intact liposome bilayer. A twofold increase in the diffusion rate of PNPA through the lipid bilayer was observed after 120 min of microwave radiation compared to temperature control samples. The microwave effect was time dependent. The enzyme activity, as a function of increased diffusion of PNPA, rises over 120 min from 22.3% to 80%. The increase in stearylamine concentration reduces the enzyme activity from 80% to 65% at 120 min. No enzyme leakage was observed. © 1994 Wiley-Liss, Inc.     

低剂量微波辐射对增强UV-B辐射损伤菘蓝幼苗抗氧化酶活性的影响

为了探讨低剂量微波对增强UV-B辐射损伤菘蓝(Isatis indigotica Fort.)的修复作用,将经过10.08 kJ·m-2·d-1辐射损伤(PAR=220 μmol·m-2·s-1)的菘蓝幼苗分别经0、3、6、9和12 s等不同时间的微波辐照(126 mW·cm-2,2 450 MHz),然后测定其幼苗MDA含量、紫外吸收物质含量、抗坏血酸含量以及3种抗氧化酶SOD、CAT和POD活性.结果表明,增强UV-B辐射损伤菘蓝在微波的作用下其菘蓝幼苗中SOD、CAT和POD活性及紫外吸收物质含量、抗坏血酸含量提高,MDA含量得到显著的降低,说明微波对增强UV-B辐射伤害菘蓝幼苗具有修复作用.但是,随着微波剂量的增加,这种修复效应减弱,甚至消失.上述参数的变化说明适量时间的微波处理可以提高菘蓝对增强UV-B辐射的抵抗能力,并在此基础上初步探讨了微波的修复机理.     

几种离子液体的微波法合成及其对脂肪酶催化效果的影响

采用微波法合成9种目标离子液体,对中间体[Bmim]Br的合成条件及其离子液体对全细胞催化剂催化效果的影响进行考察.直接将产脂肪酶真菌粗状假丝酵母(Candida valida) T2细胞固定在聚氨酯颗粒中,制备固定化细胞催化剂,将其应用于合成离子液体介质中催化甲醇与大豆油酯交换反应制备生物柴油.结果表明:微波功率200 W下间隙照射100 s,中间体[Bmim]Br的收率达95.16%,有效地提高了离子液合成产率;在[Bmim]PF6离子液中固定化细胞酶催化转酯化反应30 h,大豆油的转化率达42%,反应效果较其他8种合成离子液体好;固定化细胞颗粒和[Bmim]PF6重复使用4次,其油脂转化率和酶活保持率分别达到29%和69%,表现出较好的催化反应稳定性.     

Effect of continuous-wave and amplitude-modulated 2.45 GHz microwave radiation on the liver and brain aminoacyl-transfer RNA synthetases of in utero exposed mice

Investigations have been carried out concerning the effects of microwave (MW) exposure on the aminoacyl-transfer ribonucleic acid (tRNA) synthetase of the progeny of females that were exposed during their entire period of gestation (19 days). The changes caused by continuous-wave (CW) and amplitude-modulated (AM) MW radiation have been compared. CFLP mice were exposed to MW radiation for 100 min each day in an anechoic room. The MW frequency was 2.45 GHz, and the amplitude modulation had a 50 Hz rectangular waveform (on/off ratio, 50/50%). The average power density exposure was 3 mW/cm², and the whole body specific absorption rate (SAR) was 4.23 ± 0.63 W/kg. The weight and mortality of the progeny were followed until postnatal day 24. Aminoacyl-tRNA synthetase enzymes and tRNA from the brains and livers of the offspring (461 exposed, 487 control) were isolated. The aminoacyl-tRNA synthetase activities were determined. The postnatal increase of body weight and organ weight was not influenced by the prenatal MW radiation. The activity of enzyme isolated from the brain showed a significant decrease after CW MW exposure, but the changes were not significant after 50 Hz AM MW exposure. The activity of the enzyme isolated from liver increased under CW and 50 Hz modulated MW. © 1996 Wiley-Liss, Inc.     

Microwave radiation (2.45 GHz)-induced oxidative stress: Whole-body exposure effect on histopathology of Wistar rats

Man-made microwave and radiofrequency (RF) radiation technologies have been steadily increasing with the growing demand of electronic appliances such as microwave oven and cell phones. These appliances affect biological systems by increasing free radicals, thus leading to oxidative damage. The aim of this study was to explore the effect of 2.45 GHz microwave radiation on histology and the level of lipid peroxide (LPO) in Wistar rats. Sixty-day-old male Wistar rats with 180 ± 10 g body weight were used for this study. Animals were divided into two groups: sham exposed (control) and microwave exposed. These animals were exposed for 2 h a day for 35 d to 2.45 GHz microwave radiation (power density, 0.2 mW/cm²). The whole-body specific absorption rate (SAR) was estimated to be 0.14 W/kg. After completion of the exposure period, rats were sacrificed, and brain, liver, kidney, testis and spleen were stored/preserved for determination of LPO and histological parameters. Significantly high level of LPO was observed in the liver (p < 0.001), brain (p < 0.004) and spleen (p < 0.006) in samples from rats exposed to microwave radiation. Also histological changes were observed in the brain, liver, testis, kidney and spleen after whole-body microwave exposure, compared to the control group.

Based on the results obtained in this study, we conclude that exposure to microwave radiation 2 h a day for 35 d can potentially cause histopathology and oxidative changes in Wistar rats. These results indicate possible implications of such exposure on human health.     

Effect of Microwave and He-Ne Laser on Enzyme Activity and Biophoton Emission of Isatis indigotica Fort

The seed embryos of Isatis indigotica Fort were exposed to He-Ne laser (5.23 mW/mm2, radiated for 5 min) and microwave (1.26 mW/mm2, radiated for 8 s) irradiation to determine the effects of microwave and He-Ne laser pretreatment on enzyme activities, and biophoton emission of cotyledon. Then: (i) changes in the activities of enzymes in I. indigotica cotyledon (such as amylase, transaminase, and proteinase) were measured to investigate the effects of He-Ne laser and microwave pretreatment; and (ii) biophoton emission was measured to determine the speed of cell division and metabolism. Results from these experiments indicated that: (i) the activities of amylase, transaminase, and proteinase of the cotyledon pretreated by HeNe laser and microwave were significantly increased; and (ii) the intensity of biophoton emission was enhanced significantly by He-Ne laser and microwave irradiation. These changes suggest that He-Ne laser and microwave pretreatment can improve the inner energy of seeds, lead to an enhancement of cotyledon enzymes, and speed up the metabolism of the cell, resulting in significantly increased biophoton emission.Moreover, the mechanism of action of the effects of laser and microwave radiation on the microcalorimetric parameters, enzyme activities, and biophoton emission of seeds is discussed on the basis of the results obtained.     

微波法制备壳聚糖研究

采用微波炉加热,在敞口容器中,进行甲壳素脱乙酰反应,制备壳聚糖。考察了碱溶液浓度和微波加热时间对壳聚糖脱乙酰度的影响。固定微波加热时间30min,随NaOH溶液浓度增加,脱乙酰度先增加,后减小;NaOH溶液浓度为45％时,壳聚糖的脱乙酰度最高。固定NaOH溶液浓度为45％,随着微波加热时间延长,壳聚糖的脱乙酰度增加。微波加热的最佳时间为30min。加热时间继续延长,壳聚糖变黑。碱溶液浓度和微波加热时间对壳聚糖的粘均分子量影响都不大。本文试图从微波场的能量分布和微波加热机理方面解释实验结果。     

Synthesis of fatty acid ethyl esters with conventional and microwave heating systems using the free lipase B from Candida antarctica

Free Candida antarctica lipase B (Lipozyme, CALB L^®) was used to produce fatty acid ethyl esters (FAEE) from refined soybean oil in solvent-free media using the conventional (CHS) and microwave (MHS) heating systems. Statistical analyses (95% confidence level) for both reaction products, FAEE and free fatty acids (FFA), were performed. An increase in ethanol:oil molar ratio decreased the catalytic performance of CALB L (p?<?.05). The best conditions using the microwave radiation were a molar ratio of ethanol:oil of 3:1, a water content of 20.3?wt.% and an enzyme loading of 3?wt.% and this resulted in a total ester content of 64.7% in 15?min, while the same condition using the conventional heating gave only 21.4%. Moreover, the reaction equilibrium was reached 16 times faster with microwave than with conventional heating. High ethanol:oil molar ratios had a negative effect on FAEE synthesis with both CHS and MHS, probably due to the partial inactivation of the enzymes. MHS improved the reaction performance of CALB L, but other process parameters will have to be optimized to enhance the resulting FAEE yields. The recovery and reuse of CALB L using a MHS was demonstrated. Hence, the use of microwave radiation under the conditions applied in this study was not detrimental to the catalytic performance of CALB L for at least one reuse.     

Influence of CW microwave radiation on in vitro release of enzymes from retinol- treated hepatic lysosomes

Hepatic lysosomes were exposed in vitro to microwave radiation (2450 MHz) either prior to or simultaneously with treatment with retinol (vitamin A), and the release of the lysosomal enzymes, beta-glucuronidase, acid phosphatase, and cathepsin D, determined. A 60-min microwave exposure (10 or 100 mW/g) of retinol-treated lysosomes had no effect on the amount of release of beta-glucuronidase, cathepsin D, or acid phosphatase. In addition, 10 and 100 mW/g irradiation of lysosome fractions for 40 min prior to a 20-min retinol and microwave treatment, had no influence on the release of these enzymes. Finally, the effect of microwave radiation on the loss of latency of acid phosphatase and beta-glucuronidase from retinol-treated lysosomes was determined. Microwave radiation had no influence on the rate of appearance of these enzymes in the suspending medium. The results indicate that microwave radiation had no effect on the retinol-induced lysosomal enzyme release.     

Inactivation of rat brain acetylcholinesterase by pyridoxal 5'-phosphate

Effects of pyridoxal 5'-phosphate on the activity of crude and purified acetylcholinesterase from cerebral hemispheres of adult rat brain were examined. Acetylcholinesterase was completely inactivated by incubation with 0.5 mM pyridoxal 5'-phosphate. The enzyme activity remained unaltered in the presence of analogs of pyridoxal 5'-phosphate, pyridoxal, pyridoxamine and pyridoxamine 5'-phosphate. The inhibition of acetylcholinesterase activity by pyridoxal 5'-phosphate appeared to be of a noncompetitive nature, as determined by Lineweaver-Burk analysis. The inhibitory effect of pyridoxal 5'-phosphate on acetylcholinesterase appeared to be a general one, as the activity of the enzyme from the brains of immature chick and egg-laying hen, and from different tissues of the adult male rats, exhibited a similar pattern in the presence of the inhibitor. The inhibitory effects of pyridoxal 5'-phosphate could be reversed upon exhaustive dialysis of the pyridoxal 5'-phosphate-treated acetylcholinesterase preparations. We propose that the effects of pyridoxal 5'-phosphate are due to its interaction with acetylcholinesterase, and that it can be employed as a useful tool for studying biochemical aspects of this important brain enzyme.     

Microwave effect upon chlorpromazine-inhibited kidney ATPase

Presence of chlorpromazine, a non-active-site inhibitor of Na(+)-K(+)-ATPase catalytic activity, in a reaction system exposed to 9.14 GHz CW radiation, resulted in approximately 23% inhibition. This effect was temperature-independent within the normal range for this protein. A low-level microwave field also inhibited the enzyme catalytic rate. Loci of chlorpromazine inhibition and of low-level microwave inhibition appear to be distinct and non-interactive under the conditions of this study. Use of enzyme reaction systems as models for microwave causation of leukemia and the possible involvement of pharmacological agents, such as ouabain and chlorpromazine, in this process has been considered.     

Effect of Microwave and He-Ne Laser on Enzyme Activity and Biophoton Emission of Isatis indigotica Fort

The seed embryos of lsatis indigotica Fort were exposed to He-Ne laser (5.23 mW/mm^2, radiated for 5 min) and microwave ( 1.26 mW/mm^2, radiated for 8 s) irradiation to determine the effects of microwave and He-Ne laser pretreatment on enzyme activities, and biophoton emission of cotyledon. Then: (i) changes in the activities of enzymes in L indigotica cotyledon (such as amylase, transaminase, and proteinase) were measured to investigate the effects of He-Ne laser and microwave pretreatment; and (ii) biophoton emission was measured to determine the speed of cell division and metabolism. Results from these experiments indicated that: (i) the activities of amylase, transaminase, and proteinase of the cotyledon pretreated by HeNe laser and microwave were significantly increased; and (ii) the intensity of biophoton emission was enhanced significantly by He-Ne laser and microwave irradiation. These changes suggest that He-Ne laser and microwave pretreatment can improve the inner energy of seeds, lead to an enhancement of cotyledon enzymes, and speed up the metabolism of the cell, resulting in significantly increased biophoton emission. Moreover, the mechanism of action of the effects of laser and microwave radiation on the microcalorimetric parameters, enzyme activities, and biophoton emission of seeds is discussed on the basis of the results obtained.     

Influence of in vitro microwave radiation on the fertilizing capacity of turkey sperm

Turkey sperm were exposed to 2.45-GHz microwave radiation in a temperature-controlled wave-guide apparatus. Temperature was maintained at either 25 or 40.5 degrees C. The sperm were exposed for 30 min at a specific absorption rate (SAR) of 10 or 50 mW/g. Following irradiation, the sperm were used to inseminate virgin turkey hens artificially. During the 9 weeks following the single insemination, the following were assessed: mean number of eggs, percentage of fertile eggs, rate of decrease in egg fertility, percentage of hatched eggs, and percentage of early and late deaths. These data demonstrate that, for the conditions used in these experiments, microwave radiation has no effect on the fertilizing capacity of turkey sperm.     

Detection of microwave radiation of cytochrome CYP102 A1 solution during the enzyme reaction

Microwave radiation at 3.4–4.2 GHz frequency of the cytochrome P450 CYP102 A1 (BM3) solution was registered during the lauric acid hydroxylation reaction. The microwave radiation generation was shown to occur following the addition of electron donor NADPH to a system containing an enzyme and a substrate. The radiation occurs for the enzyme solutions with enzyme concentrations of 10^?8 and 10^?9 М. The microwave radiation effect elicited by the aqueous enzyme solution was observed for the first time. The results obtained can be used to elaborate a new approach to enzyme systems research, including studying of the mechanism of interaction of a functioning enzyme system with microenvironment.     

Effect of Microwave Radiation on Immobilization of Heavy Metals in Sediment Sludge

In order to evaluate the effect of microwave radiation on immobilization of heavy metals (Cu ^{2 +} , Cr ^{6 +} , Zn ^{2 +} and Pb ^{2 +} ) in sediment sludge, leaching tests were run under different test conditions to compare microwave radiation with conventional blast heating and drying process for their effectiveness in immobilizing heavy metals within sediment sludge. Experimental results indicate that microwave radiation can decrease the concentration of heavy metals in leachate by 63% ～ 70% more than conventional blast heating and drying process in an aclinic shake leaching test. Under the same simulated natural water conditions, the concentration of heavy metals in the leachate using microwave radiation is well below the concentration of heavy metals in leachate using conventional blast heating and drying process. It is therefore concluded that microwave radiation is much more effective than conventional blast heating and drying process in immobilizing heavy metals in sediment sludge.