Mutagenic effects of chromium trioxide on root tip cells of Vicia faba

In this study on the mutagenic effects of different concentrations of chromium trioxide (CrO3) on Vicia faba root tip, micronucleus assay and chromosome aberration assay were used to determine the mitotic indexes, micronucleus rate and chromosome aberration rate of Viciafaba root tip cells. The results showed that the effects of CrO3 concentration on the mitotic indexes were complicated. CrO3 increases the micronucleus rate of Vicia faba root tip cells. It was found that within certain range of CrO3 concentration the micronucleus rate increased systematically with increased concentration of CrO3, but that the micronucleus rate decreased at higher level of CrO3 and that CrO3 also caused various types of chromosome aberration at a rate which increased systematically with increased concentration of CrO3. We concluded that CrO3 has significant mutagenic effect on Viciafaba root tip cells.     

Mutagenic effects of chromium trioxide on root tip cells of <Emphasis Type="Italic">Vicia faba</Emphasis>

In this study on the mutagenic effects of different concentrations of chromium trioxide (CrO₃) on Vicia faba root tip, micronucleus assay and chromosome aberration assay were used to determine the mitotic indexes, micronucleus rate and chromosome aberration rate of Vicia faba root tip cells. The results showed that the effects of CrO₃ concentration on the mitotic indexes were complicated. CrO₃ increases the micronucleus rate of Vicia faba root tip cells. It was found that within certain range of CrO₃ concentration the micronucleus rate increased systematically with increased concentration of CrO₃, but that the micronucleus rate decreased at higher level of CrO₃ and that CrO₃ also caused various types of chromosome aberration at a rate which increased systematically with increased concentration of CrO₃. We concluded that CrO₃ has significant mutagenic effect on Vicia faba root tip cells. Project supported by Wenzhou Technology Bureau (No. S2002A015) and Wenzhou “551” Talented People Fund of China     

Effects of chromium nanoparticle dosage on growth,body composition,serum hormones and tissue chromium in Sprague-Dawley rats

This 6-week study was conducted to evaluate the effects of seven different levels of dietary chromium (Cr) (0, 75, 150,300, 450, 600, and 1200 ppb Cr) in the form of Cr nanoparticle (CrNano) on growth, body composition, serum hormones and tissue Cr in Sprague-Dawley (SD) rats. Seventy male SD rats (average initial body weight of (83.2±4.4) g) were randomly assigned to seven dietary treatments (n=10). At the end of the trial, body composition was assessed via dual energy X-ray absorptiometry (DEXA). All rats were then sacrificed to collect samples of blood, organs and tissues for determination of serum hormones and tissue Cr contents. The results indicated that lean body mass was significantly increased (P＜0.05) due to the addition of 300 and 450 ppb Cr from CrNano. Supplementation of 150, 300, 450, and 600 ppb Cr decreased (P＜0.05) percent body fat significantly. Average daily gain was increased (P＜0.05) by addition of 75, 150, and 300 ppb Cr and feed efficiency was increased (P＜0.05) by supplementation of 75, 300, and 450 ppb Cr. Addition of 300 and 450 ppb Cr decreased (P＜0.05) the insulin level in serum greatly. Cr contents in liver and kidney were greatly increased (P＜0.05) by the addition of Cr as CrNano in the dosage of from 150 ppb to 1200 ppb. In addition, Supplementation of 300, 450, and 600 ppb Cr significantly increased (P＜0.05) Cr content in the hind leg muscle. These results suggest that supplemental CrNano has beneficial effects on growth performance and body composition, and increases tissue Cr concentration in selected muscles.     

水分胁迫对蚕豆膜脂过氧化作用及膜保护系统的影响

经蚕豆盆栽试验,观察到水分胁迫下,蚕豆膜脂过氧化作用明显加强,O_2产生速率,MDA积累增多,质膜相对透性增大,其原因是水分胁迫下,SOD、POD、CAT等膜保护酶活性降低,活性氧代谢平衡失调所致。     

Synergistic effects of tea polyphenols and ascorbic acid on human lung adenocarcinoma SPC-A-1 cells

Tea polyphenols have been shown to have anticancer activity in many studies.In the present study,we investigated effects of theaflavin-3-3'-digallate(TF3),one of the major theaflavin monomers in black tea,in combination with ascorbic acid(AA),a reducing agent,and(-)-epigallocatechin-3-gallate(EGCG),the main polyphenol presented in green tea,in combination with AA on cellular viability and cell cycles of the human lung adenocarcinoma SPC-A-1 cells.The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) assay showed that the 50% inhibition concentrations(IC50) of TF3,EGCG,and AA on SPC-A-1 cells were 4.78,4.90,and 30.62 μmol/L,respectively.The inhibitory rates of TF3 combined with AA(TF3+AA) and EGCG combined with AA(EGCG+AA) at a molar ratio of 1:6 on SPC-A-1 cells were 54.4% and 45.5%,respectively.Flow cytometry analysis showed that TF3+AA and EGCG+AA obviously increased the cell population in the G0/G1 phase of the SPC-A-1 cell cycle from 53.9% to 62.8% and 60.0%,respectively.TF3-treated cells exhibited 65.3% of the G0/G1 phase at the concentration of its IC50.Therefore,TF3+AA and EGCG+AA had synergistic inhibition effects on the proliferation of SPC-A-1 cells,and significantly held SPC-A-1 cells in G0/G1 phase.The results suggest that the combination of TF3 with AA or EGCG with AA enhances their anticancer activity.     

BiFeO3的磁性及磁电效应

介绍了铁磁电材料BiFeO3中磁性的起源、单相材料中磁电效应的机理,并综述了BiFeO3及其与其他铁电材料的固熔体中的磁电效应.     

微波对食用油脂的性质和组成的影响研究

以五种常见食用油脂为研究对象, 采用微波加热的处理方法, 探讨了不同微波辐射强度、辐射时间对食用油脂的酸值(AV) 和过氧化值(POV) 的影响及其变化规律; 对微波处理前后油脂的组成进行红外光谱图的分析。结果表明, 油脂的酸值随微波辐射强度增大和加热时间的延长不断增大, 但变化缓慢, 而过氧化值随加热时间的延长先增大后减少再增大, 呈现曲折变化。但五种油脂的酸值和过氧化值经微波处理后均没有超过国家规定的指标, 红外光谱也表明微波加热一定时间后油脂组成未发生明显变化, 因此采用微波加热油脂是一种良好的加热方式, 为微波在油脂业中的应用提供了必要的科学依据。     

Inhibitory effects of jujuboside A on EEG and hippocampal glutamate in hyperactive rat

In this study, the inhibitory effect ofjujuboside A (JuA) on a penicillin sodium (Na-PCN) induced hyperactivity model was investigated. Cortical EEG (electroencephalogram) and the concentration of hippocampal Glutamate (Glu) were monitored simultaneously in vivo as indicators of rat's excitatory state. Power spectral density (PSD) and gravity frequency of PSD were calculated. JuA (0.05 g/L and 0.1 g/L) inhibited the EEG excitation effect caused by Na-PCN by increasing the power of δ1 and δ2bands (P＜0.01 vs model) and lowering the gravity frequency of PSD (P＜0.01 vs model). JuA also remarkably reduced the Glu elevation induced by Na-PCN (P＜0.05 vs model). Diazepam also depressed Glu concentration and lowered the gravity frequency,but it showed a different EEG pattern in increased β2-activity (P＜0.01 vs model). EEG excitation caused by Na-PCN correlated with Glu elevation during the first hour. Neurophysiological inhibitory effects of JuA and diazepam were more persistent than their Glu inhibitoty effects.     

The effect of Jujuboside A on the evoked field potentials of granule cells in dentate gyrus

Jujuboside A (JuA) is a main component of Jujubogenin extracted from the seeds of Ziziphus. The authors have not seen any report on JuA's direct effect on the neurons of the central nervous system. This study aimed to assess the effect of JuA on paired-pulse responses of dentate gyrus granule cells in urethane-anaestherized rats, used intracerebroventricular (i. c. v.) JuA to mimic in vitro bath conditions in vivo. Paired-pulse stimuli with 80ms interpulse interval were used to stimulate the perforant pathway. Evoked responses were recorded in the dentate gyrus cell layer after i. c. v. administration of 0.9% normal saline or JuA. In the first responses, the slopes of excitatory postsynaptic potential (EPSP1) and the amplitudes of population spike (PS1) decreased significantly after administration of JuA while the PS1 latencies increased significantly. In the second responses, the EPSP2 slopes and PS2 latencies were changed similarly to those of the first ones, but PS2 amplitudes increased. The results showed that JuA may have some inhibitory effect on the granule cell excitability mediated by presynaptic mechanism but may have little effect on the excitability mediated by postsynaptic mechanism since the second evoked N-methyl-D-aspartic mediating paired-pulse facilitation is a postsynaptic mechanism. Project supported by the National Key Scientific and Technological Planning Fund of China (Grant 99-929-04-03), and by the Visiting Scholar Fund of Key Laboratory from the Education Ministry of China     

Epigallocatechin-3-gallate affects the growth of LNCaP cells via membrane fluidity and distribution of cellular zinc

Objective: To evaluate effects of epigallocatechin-3-gallate (EGCG) on the viability, membrane properties, and zinc distribution, with and without the presence of Zn2+, in human prostate carcinoma LNCaP cells. Methods: We examined changes in cellular morphology and membrane fluidity of LNCaP cells, distribution of cellular zinc, and the incorporated portion of EGCG after treatments with EGCG, Zn2+, and EGCG+Zn2+. Results: We observed an alteration in cellular morphology and a decrease in membrane fluidity of LNCaP cells after treatment with EGCG or Zn2+. The proportion of EGCG incorporated into liposomes treated with the mixture of EGCG and Zn2+ at the ratio of 1:l was 90.57%, which was significantly higher than that treated with EGCG alone (30.33%). Electron spin resonance (ESR) studies and determination of fatty acids showed that the effects of EGCG on the membrane fluidity of LNCaP were decreased by Zn2+. EGCG accelerated the accumulation of zinc in the mitochondria and cytosol as observed by atomic absorption spectrometer. Conclusion: These results show that EGCG interacted with cell membrane,decreased the membrane fluidity of LNCaP cells, and accelerated zinc accumulation in the mitochondria and cytosol, which could be the mechanism by which EGCG inhibits proliferation of LNCaP cells. In addition, high concentrations of Zn2+ could attenuate the actions elicited by EGCG.     

Joint application of feature extraction based on EMD-AR strategy and multi-class classifier based on LS-SVM in EMG motion classification

This paper presents an effective and efficient combination of feature extraction and multi-class classifier for motion classification by analyzing the surface electromyografic(sEMG) signals. In contrast to the existing methods,considering the non-stationary and nonlinear characteristics of EMG signals,to get the more separable feature set,we introduce the empirical mode decomposition(EMD) to decompose the original EMG signals into several intrinsic mode functions(IMFs) and then compute the coefficients of autoregressive models of each IMF to form the feature set. Based on the least squares support vector machines(LS-SVMs) ,the multi-class classifier is designed and constructed to classify various motions. The results of contrastive experiments showed that the accuracy of motion recognition is improved with the described classification scheme. Furthermore,compared with other classifiers using different features,the excellent performance indicated the potential of the SVM techniques embedding the EMD-AR kernel in motion classification.     

Effect of serum concentration on adhesion of monocytic THP-1 cells onto cultured EC monolayer and EC-SMC co-culture

Background:The adhesion of monocytes to the endothelium following accumulation oflow-density lipoprotein(LDL) in subendothelial spaces is an important step in the development of intimal hyperplasia in arterially implanted vein grafts and atherosclerosis in both animals and humans.However.it iS not well known how serum factors affect the adhesion of monocytes.Methods:We have studied the efrect of fetal calf serum(FCS).which we considered a source of LDL.on the adhesion of monocytes to endothelial cells(Ecs)by using human monocytic THP-1 cells and both a monolayer of cultured bovine aortic endothelial cells(EC monoculture)and a co-culture with bovine aortic smooth muscle cells(EC-SMC co-culture).Results:It was found that the addition of FCS to the medium greatly affected the adhesion of THP-1 cells,and the higher the concentration of FCS in the medium,the greater the adhesion of THP-1 cells to endothelial cells.Adhesion of THP-1 cells to an EC-SMC co-culture Was approximately twofold greater than that to an EC monoculture,and after adhering to endothelial cells,many THP-1 cells transmigrated into the layer of smooth muscle cells.Conclusion:The results suggest that the elevation of the LDL(cholesterol)level in blood provides a favorable condition for the development of intimal hyperplasia and atherosclerosis by promoting the adhesion of monocytcs to the endothelium and their subsequent migration into subendothelial spaces.     

关于冬虫夏草对乙型肝炎疗效及对免疫性肝损伤保护作用的研究

根据近10多年的研究报导及课题组的研究结果，综述了冬虫夏草（CS）对乙型肝炎的治疗效果及对免疫性肝损伤的保护作用。试验证明，乙型肝炎患者经CS治疗后，HbeAg有较高的阴转率，ALT、AST等肝功能指标明显改善，乏力、纳差等症状也大为好转，患者外周血中的CD3、CD4、CD4/CD8均明显提高。即便发生肝硬化者，经一定疗程CS治疗后，硬化症状减轻，肝纤维化得到有效控制和减轻。对免疫性肝损伤有很好的保护作用。     

初探石墨薄膜的表面结构及导电性

论述了在常温下和在大气状态下,扫描隧道显微镜（STM）在石墨薄膜表面上的电场加工实验,并对作用机理进行了分析,认为表面结构现象生成是场蒸发效应作用的结果,其导电性受外电场力的大小和薄膜层数之间的束缚力的影响。     

年龄和学习时间对英语语音的影响

人们普遍认为儿童在第二语言学习方面要优于成人,尤其他们在语音方面的特殊能力给人留下深刻印象,这也是从小学开始外语教育的一个普遍依据。实验通过对60个年龄在13-35岁的中国学生所做的语音测试考察年龄和学习时间对英语语音的影响。实验证明年龄是影响语音能力的一个重要因素,在青春期前学习外语的学生更有可能达到标准的语音水平。     

Effects of La^3＋on microwave dielectric properties of（Pb0.5Ca0.5）（Fe0.5Ta0.5）O3ceramics

This work investigated the microwave dielectric properties of A-site substitution by rare earth La3+in(Pb0.5Ca0.5)(Fe0.5Ta0.5)O3(PCFT) system.A single perovskite phase was obtained only when the doping content was 2%.Suitable La3+ doping improved microwave dielectric performances.Excessive La3+doping caused the formation of secondary phase,which resulted in the decreasing of permittivity εrand quality factor Qfvalues.Especially,when the doping content is 2%-5%,permittivity εrwas above 75 and Qfvalues were 6...     

Effects of rosuvastatin on the production and activation of matrix metalloproteinase-2 and migration of cultured rat vascular smooth muscle cells induced by homocysteine

Objective: To test the influence of homocysteine on the production and activation of matrix metalloproteinase-2 (MMP-2) and tissue inhibitors of matrix metalloproteinase-2 (TIMP-2) and on cell migration of cultured rat vascular smooth muscle cells (VSMCs). Also, to explore whether rosuvastatin can alter the abnormal secretion and activation of MMP-2 and TIMP-2 and migration of VSMCs induced by homocysteine. Methods: Rat VSMCs were incubated with different concentrations of homocysteine (50–5 000 μmol/L). Western blotting and gelatin zymography were used to investigate the expressions and activities of MMP-2 and TIMP-2 in VSMCs in culture medium when induced with homocysteine for 24, 48, and 72 h. Transwell chambers were employed to test the migratory ability of VSMCs when incubated with homocysteine for 48 h. Different concentrations of rosuvastatin (10⁻⁹–10⁻⁵ mol/L) were added when VSMCs were induced with 1 000 μmol/L homocysteine. The expressions and activities of MMP-2 and TIMP-2 were examined after incubating for 24, 48, and 72 h, and the migration of VSMCs was also examined after incubating for 48 h. Results: Homocysteine (50–1 000 μmol/L) increased the production and activation of MMP-2 and expression of TIMP-2 in a dose-dependent manner. However, when incubated with 5 000 μmol/L homocysteine, the expression of MMP-2 was up-regulated, but its activity was down-regulated. Increased homocysteine-induced production and activation of MMP-2 were reduced by rosuvastatin in a dose-dependent manner whereas secretion of TIMP-2 was not significantly altered by rosuvastatin. Homocysteine (50–5 000 μmol/L) stimulated the migration of VSMCs in a dose-dependent manner, but this effect was eliminated by rosuvastatin. Conclusions: Homocysteine (50–1 000 μmol/L) significantly increased the production and activation of MMP-2, the expression of TIMP-2, and the migration of VSMCs in a dose-dependent manner. Additional extracellular rosuvastatin can decrease the excessive expression and activation of MMP-2 and abnormal migration of VSMCs induced by homocysteine.     

基于学习遗忘作用的人员调度实验设计及其软件开发

建立了学习遗忘作用与人员工效的关系模型。采用遗传算法进行调度求解,并在Matlab环境下完成了考虑学习遗忘作用的人员调度的软件开发,设计了相关实验,通过实验内容可以实现多任务人员的调度,并表明调度过程中的学习遗忘现象。通过对参数和约束条件的设置,模拟了不同生产类型,并产生人员在不同生产模式下的调度策略。