Effect and mechanism of on-chip electrostatic discharge protection circuit under fast rising time electromagnetic pulse

The electrostatic discharge(ESD)protection circuit widely exists in the input and output ports of CMOS digital circuits,and fast rising time electromagnetic pulse(FREMP)coupled into the device not only interacts with the CMOS circuit,but also acts on the protection circuit.This paper establishes a model of on-chip CMOS electrostatic discharge protection circuit and selects square pulse as the FREMP signals.Based on multiple physical parameter models,it depicts the distribution of the lattice temperature,current density,and electric field intensity inside the device.At the same time,this paper explores the changes of the internal devices in the circuit under the injection of fast rising time electromagnetic pulse and describes the relationship between the damage amplitude threshold and the pulse width.The results show that the ESD protection circuit has potential damage risk,and the injection of FREMP leads to irreversible heat loss inside the circuit.In addition,pulse signals with different attributes will change the damage threshold of the circuit.These results provide an important reference for further evaluation of the influence of electromagnetic environment on the chip,which is helpful to carry out the reliability enhancement research of ESD protection circuit.

In Vitro Antioxidant and Radio Protective Activities of Lycopene from Tomato Extract against Radiation—Induced DNA Aberration

Background: The accumulation of free radicals is linked to a number of diseases. Free radicals can be scavenged by antioxidants and reduce their harmful effects. It is therefore essential to look for naturally occurring antioxidants that come from plants, as synthetic antioxidants are toxic, carcinogenic and problematic for the environment. Lycopene is one of the carotenoids, a pigment that dissolves in fat and has antioxidant properties. Materials and Methods: The antioxidant and free radical scavenging activity were assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The impact of lycopene on bacteria (E. coli) susceptibility to γ-radiation was examined by radio sensitivity assay. The study also examined the induction of strand breaks in plasmid pUC19 DNA and how lycopene extract protected the DNA from γ-radiation in vitro. Results: At varying concentrations, lycopene demonstrated its ability to scavenge free radicals such as 2, 2-diphenyl-1-picrylhydrazyl (DPPH). IC50 for lycopene was determined at 112 μg/mL which was almost partial to IC50 of standard antioxidant L-ascorbic acid. The D10 value 180 Gy of E. coli was found to be >2-fold higher in the extract-containing lycopene sample than in the extract-free controls. The lycopene extracts inhibited the radiation-induced deterioration of the plasmid pUC19 DNA. At an IC50 concentration, lycopene provided the highest level of protection. Conclusion: Lycopene functions as an efficient free radical scavenger and possible natural antioxidant source. For cancer patients and others who frequently expose themselves to radiation, lycopene may be a useful plant-based pharmaceutical product for treating a variety of diseases caused by free radicals.

Damage to DNA of effective microorganisms by heavy metals:Impact on wastewater treatment

The research is to test the damage to DNA of effective microorganisms(EMs)by heavy metal ions As3+,Cd2+,Cr3+,Cu2+,Hg2+, Pb2+,and Zn2+,as well as the effects of EM bacteria on wastewater treatment capability when their DNA is damaged.The approach applied in this study is to test with COMET assay the damage of EM DNA in wastewater with different concentrations of heavy metal ions As3+,Cd2+,Cr3+,Cu2+,Hg2+,Pb2+,Zn2+,as well as the effects of EM treated with As3+,Cd2+,Cr3+,Cu2+,Hg2+,Pb2+,and Zn2+ on COD degradin...

Protective Effect of Dimethyl-4,4'-Dimethoxy-5,6,5',6'-Dimethylene Dioxybiphenyl-2,2'-Dicarboxylate (DDB) against Carcinogen-Induced Rat Liver Nuclear DNA Damage

The protective effect of DDB against carcinogen-induced DNA damage was examined in the present investigation. Preincubation of rat liver nuclei with DDB (1 mmol.L-1) resulted in 60% inhibition of binding of 3H-benzo (a) pyrene to nuclear DNA. Unscheduled DNA synthesis (UDS) induced by aflatoxin BI (10^(-7) mol.L-1) in freshly isolated rat hepatocytes was also inhibited by DDB (10^(-6)-10^(-3)mol.L-1). Oral administration of DDB at 200 mg.kg-1 once daily for 3 d induced a significant increase of liver cytosol glutathione-S-transferase and microsomal UDPG-transferase activity in mice. These results indicate that DDB is able to directly or indirectly antagonize certain carcinogen-induced DNA damages.

DNA损伤效应主动监测的抗氧化基因缺失微生物传感器的构建及性能评价

目的活性氧基团(ROS)水平升高会引起生物体的DNA氧化损伤,监测DNA的氧化损伤程度,能够实现ROS损伤效应的有效评价。基于微生物传感器监测DNA损伤效应可以定量评价氧化损伤程度,但微生物本身具有的ROS清除机制,会影响监测灵敏度。本研究旨在敲除细菌ROS清除机制的关键基因,构建抗氧化基因缺失微生物传感器,实现对DNA损伤效应的灵敏监测,评价ROS对生物体的损伤效应。方法本研究基于λ-Red同源重组的方法敲除细菌抗氧化损伤相关基因ahpCF、katE与katG,构建抗氧化基因缺失微生物传感器,并评价传感器对萘啶酮酸钠和紫外照射的响应。结果成功构建ΔahpCF、ΔahpCF/ΔkatE与ΔahpCF/ΔkatE/ΔkatG三种抗氧化基因缺失的微生物传感器,工程菌ΔahpCF/ΔkatE/ΔkatG对DNA损伤试剂萘啶酮酸钠的响应灵敏度最高,检测限为0.40μmol/L,另外,1.80 min的紫外照射(254 nm)可诱导工程菌产生显著的荧光表达效应。结论本研究构建了抗氧化基因缺失微生物传感器,实现了对DNA损伤试剂和紫外照射等DNA损伤效应的主动灵敏监测,可为未来空间辐射效应的评价提供一种主动、有效、灵敏的潜在监测方法。

DNADam ageEffectsofHydroxyapatiteUltrofinePowderonW-256 Sarcom a Cells and Lym phocytes in Rats

To explore the anticancer mechanism and DNA damages of hydroxyapatite ultrofine powder (HAUFP) on lymphocytes of rats, DNA damages in W 256 sarcoma cells and lymphocytes of rats were measured by single cell gel electrophoresis (SCGE). The results showed that HAUFP damaged DNA of W 256 sarcoma cells obviously but only cause slight damage of DNA of lymphocytes in rats. It is suggested that HAUFP selectively damaged DNA of tumor cells with only mild damage of lymphocyte DNA. HAUFP has powerful anticancer effect and little genetic toxicity.

Protective Effects of Dimethyl-4,4'-Dimethoxy-5,6,5',6'-Dimethylene Dioxybiphenyl-2,2'-Dicarboxylate on Damages of Isolated Rat Hepatocytes Induced by Carbon Tetrachloride and D-galactosamine

The protective effect of biphenyl dimethyl dicarboxylate (DDB) on chemically induced damages was studied in isolated suspended rat hepatocytes. The experimental results showed that DDB (200μg/106 cells) efficiently protected the hepatocytes against carbon tetrachloride (CC14 10 mrnol.L-1) and D-galactosamine (1 mmol.L-1) induced damages. Membranal lipid peroxidation (malondialdehyde, MDA formation) and glutamic pyruvic transaminase (GPT) release from the hepatocytes were markedly decreased. The damage of the cell surfaces of the hepatocytes were also reduced as seen under a scanning electron microscope (SEM). Pretreatment with DDB (300 mg-kg-1) orally ameliorated the reduction of liver glycogen and blood glucose caused by ip injection of D-galactosamine (800 mg-kg-1) in mice. When normal rats were given DDB 300 mg-kg-1 once daily for 10 d, the free ribosomal protein and RNA in the liver increased significantly. These results indicate that DDB is of beneficial effects on both damaged and normal hepatocytes.

EFFECT OF GLYCYRRHETINIC ACID ON DNA DAMAGE AND UNSCHEDULED DNA SYNTHESIS INDUCED BY BENZO（α）PYRENE

Glyeyrrhetinic acid (GA) is an active component of Glycyrrhiza uraleusis fisch,In this study,GA was found to inhibit ear edema and ornithine decarboxylase (ODC)activity induced by croton oil in mice. GA could also protect rapid DNA damage and decrease the unscheduled DNA synthesis induced by benzo(α)pyrene. The results demonstrate that GA has a potential cancer chemopreventive activity.

Protective Effect of Vitamin E on Liver Damage Induced by 2-Chloro-1, 3-butadiene

The present study was performed to determine the influence of lipid peroxidation and perturbance of Ca2+ homeostasis on liver damage induced by 2-chloro-1, 3-butadiene (CBD) and the protective effects of vitamin E in Wistar rats. Animals were given intraperitoneally different doses (8,40 or 200 mg·kg-1 daily) of CBD for 21 days, and the following dose-dependent events were observed: liver damage, significant increase in liver lipid peroxides, and decreases in activities of erythrocytic glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). The pretreatment of rats with vitamin E (po 150 mg·kg-1) before administering CBD (iP 60 mg·kg-1 ) daily for 21 days prevented the following CBD-induced changes, the increase in serum cholylglycine (CG), hepatic LP, hepatic mitochondrion LP, hepatic oxidized glutathione (GSSG) (while the significant increase of reduced glutathione (GSH) was not affected) and the decrease in activities of erythrocytic SOD and hepatic mitochondrial calcium sequestration. These results suggest that lipid peroxidation and perturbance of Ca2+ homeostasis appear to contribute to the hepatotoxicity of CBD, and vitamin E might prevent the liver damage induced by CBD. The decrease in activities of GSH-Px and SOD in erythrocytes might be used as biomarkers for adverse effects of CBD on defense system against lipid peroxidation.

Typical Cell Signaling Response to Ionizing Radiation: DNA Damage and Extranuclear Damage

To treat many types of cancer, ionizing radiation （IR） is primarily used as external-beam radiotherapy, brachytherapy, and targeted radionuclide therapy. Exposure of tumor cells to JR can induce DNA damage as well as generation of reactive oxygen species （ROS） and reactive nitrogen species （RNS） which can cause non-DNA lesions or extracellular damage like lipid perioxidation. The initial radiation-induced cell responses to DNA damage and ROS like the proteolytic processing, as well as synthesis and releasing ligands （such as growth factors, cytokines, and hormone） can cause the delayed secondary responses in irradiated and unirradiated bystander cells through paracrine and autocrine pathways.

Galantamine protects against beta amyloid peptide-induced DNA damage in a model for Alzheimer's disease

Alzheimer’s disease（AD）is the most common type of dementia in elderly population.With a growing aging population not only in the United States but also in the worldwide,AD constitutes an emergent public health problem.

THE PROTECTIVE EFFECT OF Na^+ CHANNEL BLOCKERS AGAINST CELL DAMAGE CAUSED BY ISCHEMIA

In order to observe it blockers of sodium channel obsesses the neuroprotective effect on hippocampal CA 1 pyramidal cell under the condition of transient brain ischemia, the present experiment used 24 male Wistar rats aged 9 months and divided them into four groups. Lidocaine and/or furosemide were injected introcerebroventicularlly (I.C.V). Stained with H E and accounted the CA 1 pyramidal cell numbers by computer in each group suggested following findings: Although 5 μl of 2% lidocaine was injected I.C.V, the results indicated lidocaine didn't have any blockade to pyramidal cell injuries in hippocampal CA 1 area (P<0 05). In the group medicated with 2 5μl of both 2% lidocaine and 2% furosemide, the results showed that the combined approach had a blockade to injuries of pyramidal cells compared with control group (P<0 01). The present experiment indicates that the combined blockade of lidocaine and furosemide injected I.C.V. to Na + channel can prevent the injuries from hippocampal neurons owing to ischemia.

The genotoxic effects of benzo[a]pyrene and methamidophos on black porgy evaluated by comet assay

In this study, two common pollutants (benzo[a]pyrene and methamidophos) in marine environment were tested by comet assay for their inducement of in vivo genotoxic effect to the blood cells of black porgy ( Acanthopagrus schlegeli). The fish was exposed to 2 μg/L of benzo[a]pyrene (BaP) and methamidophos, and their mixture. The assay was performed on whole blood at 2 h, 5 h, 24 h and 96 h exposure intervals. A signifi- cant increase in DNA damage was observed in each treatment with the pollutants. Additive effect of BaP and methamidophos was also found in the experiment. However, the decrease ratios of DNA damage for 5 h and 96 h exposure interals compared with 2 h and 24 h exposure ones, respectively, were noticed. This phenomenon may be explained by the function of repairing process via enzyme cytochrome P450 in the animal. Evidence of the genotoxicity of organophosphorus pesticides (OPs) and polynuclear aromatic hydrocarbons (PAHs) on marine fish are discussed in this paper.

Effectiveness of an Secondary Prevention Program in Chronic Kidney Disease

Background: There are many programs which focus on late-stage chronic kidney disease (CKD), and it is considered that further evidence needs to be generated regarding the effectiveness of the programs used before renal replacement therapy. Study Design: A cohort study. Settings & Participants: Patients over 15 years of age who had been diagnosed with CKD according to the KDOQI (Kidney Disease Outcomes Quality Initiative) guidelines and who had undergone conventional treatment (CT) or a renal protection program (RPP). These were patients of two Colombian health insurance companies. Predictors: Age, sex, marital status, comorbidities, CKD stage, and clinical indicators. Outcomes: First CKD progression, and need for renal replacement therapy (RRT). Measures: Clinical marker. Results: The RPP is structurally and functionally different from the CT. It offers the interdisciplinary management of patients, a greater number of medical appointments, and patients start to receive treatment at younger ages and at earlier stages of their condition. The clinical markers of the patients following the RPP are within adequate ranges, and their renal function is less impaired, despite the differences in basal conditions. Upon finishing the study, we found that patients who received CT had a higher risk of receiving nephrotoxic drugs and not receiving nephroprotective drugs. The explanatory variables for the first progression were age, stage, history of dyslipidemia, and hemoglobin, potassium, and albumin levels. These variables, together with glycemia levels were also valid for RRT, except for history of dyslipidemia, as it was not significant. Upon adjusting for the explanatory variables, it was found that belonging to the RPP and attending more appointments had a protective effect in the process of controlling renal damage. Limitations: A possible selection bias. Conclusions: Belonging to a structured renal protection program is an effective way to keeping the clinical markers associated with renal impairment within normal ranges.

不同采收期虫草参多酚对羟基自由基介导的DNA氧化损伤保护作用的研究

采用Folin-酚法测定两个采收地(S1和S2)三个采收期(T1、T2和T3)虫草参游离酚和结合酚提取物的多酚含量。采用HPLC法检测多酚提取物中没食子酸、绿原酸、咖啡酸和迷迭香酸的含量。同时,评价了虫草参多酚提取物对羟基自由基(·OH)介导的DNA氧化损伤的保护作用。结果显示,虫草参游离酚和结合酚提取物的多酚含量范围分别为86.53~181.40和89.70~193.58μg GAE/mg;咖啡酸在结合酚中含量较高,且S2采收地高于S1;而迷迭香酸在游离酚中含量较高,且在T1和T3采收期,S2采收地的高于S1,相反在T2采收期,S2采收地的低于S1;虫草参游离酚(25~300μg/mL)和结合酚(3.125~50μg/mL)提取物对DNA氧化损伤保护作用的双螺旋百分比范围分别为1.81%~55.04%和1.67%~70.83%。相较于游离酚,结合酚提取物表现出更好的保护效果。

端粒DNA损伤修复机制及其意义

DNA损伤是细胞存活的主要威胁,若得不到恰当的修复,可能引起细胞衰老、死亡或者肿瘤的发生。真核生物线性染色体的末端保护依赖于端粒,端粒在维护基因组稳定性中具有重要的作用。端粒末端的特殊结构需要避免被识别为DNA损伤位点,从而避免发生降解、重组以及末端连接。然而,端粒DNA富含鸟嘌呤,易受活性氧自由基攻击而产生损伤。细胞如何平衡末端保护与DNA损伤修复是一个重要的问题。本文将围绕端粒末端保护机制以及端粒DNA损伤修复最新研究进行综述。端粒随着细胞增殖而逐渐变短,最终引起细胞衰老。肿瘤细胞具有延伸端粒的能力,主要通过端粒酶或端粒延伸替代机制维持端粒长度。端粒在衰老以及肿瘤发生发展中扮演了重要的作用,本文还将总结端粒DNA损伤修复在衰老和肿瘤防治中的意义。

Flow cytometric investigation on degradation of macro-DNA by common laboratory manipulations

The degree and characteristics of physical degradation of macro-DNA molecules by common laboratory manipulations are reported. With linearized lambda-phage viral DNA as the model DNA, fragmentation of macro-DNA by various indispensable laboratory manipulations were investigated using a high sensitivity flow cytometric setup. Investigated manipulations included pipetting, vortexing, rocking, freeze-thawing, ultrasonication and ultrafiltration. “Exhaustive counting” of the intact lambda DNA molecules following such manipulations enabled a quantitative assessment of the resulting fragmentation, which also revealed the type of degradation reflected in the fragmentation patterns. The use of high sensitivity flow cytometry was especially suited to investigate the degradation of dilute DNA solutions that may not be suitable for analysis using traditional methods. Notable findings of this study included: the boarderline-size of DNA chains in terms of susceptibility to shear stresses by such manipulations;discernable instability of nicked DNAs;shattering-fragmentation of DNAs by freeze-thawing or ultrasonication;effectiveness of some protection media;marked “self-protection effect” of concentrated DNA solutions. These findings support and refine our traditional knowledge on how to maintain the physical integrity of macro-DNA molecules against inevitable laboratory manipulations.

化学发光法研究莲房原花青素的体外抗氧化活性和对DNA损伤的保护作用

采用多个化学发光体系,研究了测定莲房原花青素(LSPC)的体外抗氧化活性及其对DNA损伤的保护作用。运用邻苯三酚-鲁米诺化学发光体系测定了LSPC对超氧阴离子的清除作用,硫酸铜-邻菲啰啉-抗坏血酸-双氧水、硫酸亚铁-鲁米诺-双氧水和硫酸亚铁-鲁米诺三个体系测定了LSPC对羟基自由基的清除作用,双氧水-鲁米诺体系测定了LSPC对体外双氧水的清除作用,采用硫酸铜-邻菲啰啉-抗坏血酸-双氧水-脱氧核糖核酸测定了LSPC对体外DNA损伤的保护作用。实验结果表明LSPC具有较好的体外清除活性氧和保护DNA损伤的活性,但是在不同体系中LSPC的抗氧化能力存在差异。

山楂果肉原花青素的体外抗氧化活性和对DNA损伤的保护作用

研究了化学发光法测定山楂果肉原花青素(procyanidins of Hawthorn Sarcocarp简称HSPC)的体外抗氧化活性及其对DNA损伤的保护作用。运用邻苯三酚-鲁米诺化学发光体系测定了HSPC对超氧阴离子的清除作用,硫酸铜-邻菲啰啉-抗坏血酸-双氧水体系测定了HSPC对羟基自由基的清除作用,双氧水-鲁米诺体系测定了HSPC对体外双氧水的清除作用,采用硫酸铜-邻菲啰啉-抗坏血酸-双氧水-脱氧核糖核酸测定了HSPC对体外DNA损伤的保护作用。结果表明:当HSPC浓度为1mg/mL时,对超氧阴离子抑制率达87.7%,其半数抑制率浓度IC50值为130.8μg/mL;100μg/mL时对羟基自由基抑制率达91.7%,IC50值为61.73μg/mL;8μg/mL时对双氧水抑制率达91.6%,IC50值为0.19μg/mL;40μg/mL时对体外DNA损伤抑制率达80.7%,IC50值为22.16μg/mL。表明HSPC具有很好的体外清除活性氧和保护DNA损伤的活性。

精子DNA损伤与保护

精子DNA损伤是引起不育的重要原因,携有DNA损伤的幸存精子可能逃避体内精子选择机制而成熟并将遗传缺陷传递于后代。因此对精子DNA损伤的研究已成为生殖医学的热点之一。损伤精子DNA的因素主要包括氧化应激、微量元素、精子毒性物质、放射线等,而机体则凭借高度压缩精子DNA、抗氧化系统等机制保护精子DNA的完整性。此外,一些药物如抗氧化剂、黑茶提取物等也可以促使这种保护机制的健全与重建。