bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Pre-Oxidized CuO Layer in Joining between Polyethylene Terephalate (PET) and Copper (Cu) by Using Pulsed Nd:YAG Laser
Authors: Binti Yusof Farazila , Mutoh Yoshiharu , Miyashita Yukio
Published: August 2010

In the present study, effect of pre-oxidized (PO) CuO layer in the joining between polyethylene terephalate (PET) and copper (Cu) by using pulsed Nd:YAG laser was investigated. The experimental result for PET/PO Cu (with pre-oxidized layer) and PET/Cu (without pre-oxidized layer) were presented in this paper. The results showed the pre-oxidation surface improved the welding efficiency. The welded area and tensile shear failure load (TSFL) of PET/PO Cu joint were increased when pre-oxidized layer was introduced. This indicates that high heat was absorbed during laser irradiation of PET/PO-Cu joint compare to PET/Cu joint. On the other hand, the fracture surface of PET/PO-Cu showed the presence of Cu and Cu oxide particles in the PET side. While in case of PET/Cu, no occurrence of Cu particles can be observed. The presence of Cu oxide particles and Cu particles were believed may increase PET/PO Cu joint shear force. From the cross-sectional observation of PET/PO Cu joint interface, it was found that an oxide layer in the laser irradiation area was removed and PET seemed to have intimate contact with Cu surface.
An Exploratory Study on Agriculture Risk Management Based on Ontology
Authors: Pan Qin , Liu Chun Nian , Yang De Hui
Published: August 2010

With the rapid growth of information resources and increasing individual demands of farmers, the problem of how to organize complicated information effectively in agricultural risk management and provide efficient information services has become more and more important. Research on architecture of agricultural risk-oriented domain ontology-based information integrated service is studied. The ontology molecule theory, which is a new theory in ontology field, is introduced and utilized in this paper. Based on the ontology molecule theory, the paper builds a frame of the agricultural risk ontology and proposes the architecture and implementation of the agricultural risk-oriented information integrated service. At the end, this article points out that the future research is to establish an ontology-based information service system for the agricultural risk management, in order to better predict the agricultural risk and reduce its effect to farmers.
Models of Agriculture Risk Management with Agriculture Ontology
Authors: Zhou Kun , Liu Chun Nian
Published: August 2010

with economic globalization and market-oriented agricultural economy, the impact factors of agricultural risks become more complicated. As a variety of factors intertwine together, the traditional Expert System is difficult to identify and manage agricultural risks, which greatly hampers the process of agricultural risk management. To overcome this problem, we introduce the ontology theory. By constructing agricultural risk ontology and agricultural risk strategy ontology, we can resolve the problem of agricultural risk's description and identification, and improve the efficiency and reliability of agricultural risk management. In this paper, we introduce the domain ontology theory to the field of agricultural risk management, and describe the basic process of the domain ontology-based agricultural risk management. And then, we propose a framework of ontology-based agricultural risk management and specifically introduce each module in the framework. Meanwhile, based on the method of building ontology, this article constructs the basic frame of the agricultural risk ontology. Finally, to take the drought risk for example, the paper analyses the implementation process and technologies of the domain ontology-based agricultural risk management.
Sintering and Crystallization Behavior in Li2O-Al2O3-SiO2 (LAS) Glass
Authors: Im Sang Hyeok , Kim Nam Jin , Kim Dong Hwan , Kweon Jae Young , Koo Dong Keon , Kim Tae Hee , Heo Seong Hyeon , Yoon Duck Ki , Ryu Bong Ki
Published: August 2010

The study investigated the crystallization and sintering behavior in Li2O-Al2O3-SiO2 (LAS) glass powder. The sintered sample was produced with a glass particle (Φ=44㎛). The relative density and transmittance of the sintered samples showed the highest value at the temperature of 650°C. In the higher temperature than 650°C, the crystal growth occurred to decrease the densification of Li2O-Al2O3-SiO2 (LAS) glass powder. Main crystalline phase was β-spodumene in the glass powder. From the non-isothermal differential thermal analysis, the crystallization of the particles (Φ=44㎛) was observed at 640~684°C with respect to the heating rate. The activation energy of crystallization (EC) and Avrami constant (n) calculated by Kissinger and Ozawa equations indicated that the surface and the bulk crystallization occurred simultaneously in the glass. The optimum sintering condition of this glass powder was 650°C without crystal growth of β-spodumene, although a nucleation or nano-crystal growth occurred.
Study on Optimization of CMP Slurry for Tantalum in ULSI Based on Taguchi Method
Authors: Mu Hui Lai , Wang Sheng Li , Li Zhen Xia , Xu Wen Zhong , Xiang Xia
Published: August 2010

Chemical mechanical polishing (CMP) has become an essential technique in advanced ULSI process. The mechanism of Ta CMP is discussed in this paper. According to the physical and chemical properties of Ta, the alkaline polishing slurry and proper process parameters for Ta CMP are prepared. The paper optimized four key parameters-abrasive concentration, organic alkali, oxidant and surfactant concentration, obtained the comprehensive optimized slurry used in evaluating the removal rate using Taguchi method. The results indicate that: abrasive concentration is 10%, the organic alkali concentration is 15ml/L, the oxidant concentration is 10ml/L and the surfactant concentration is 10ml/L, higher removal rate can be obtained.
First Principles Calculation of Adhesion at Fe/WC Interface
Authors: Chen Nai Chao , He Ping , Li Da Chang
Published: August 2010

Using a first principles methodology, the adhesion of tungsten carbide and ferritic steel is investigated to estimate the mechanism of cutting process, which facilitates cutting performance enhancement and working lifetimes elongating. The Fe (100)/WC (100) interface is adopted based on minimum mismatched lattices with aiming to provide the suitable models to explore the structural and electronic properties at the interface. The W- and C-terminated surfaces are employed to clear the features of different surfaces of tungsten carbide. The comparisons of DOS, including bulk WC, Fe and their low index surfaces, show that surface-induced feature is generally presented on the surfaces. Bond character at the interface is studied with difference charge density and electron localization function (ELF), which allow us to predict the interfacial strength. Adhesion is due to strong covalent Fe-C bonds at the C-terminated interfaces, while W-terminated interface has no enough evidence to verify the presentation of covalent bonds. The calculated results support some advanced atomic studies on complex interface structures, especially improving the surface quality of metal products after machining process.
Instable Plasticity and Precipitation in AZ91D Magnesium
Authors: Zeng Shao Feng , Chen Wen Zhe
Published: August 2010

Instable plasticity, which is normally a consequence of interactions between diffusing solute atoms and dislocations, is observed in AZ91D magnesium at room temperature. Experimental measurements of different heat treatment of AZ91D magnesium were taken to investigate different influence on PLC effect by the presence and structural state of second phase in this study. Tensile specimens were tested at room temperature at a crosshead speed of 0.6 mm/min. The results indicate that some number of large,coherent precipitates prevents serrated flow by way of trapping vacancies, but small precipitates content do not supress it.
Structures and Properties of Alkyl-Phosphate Potassium Salts
Authors: Yang Hong Xiang , Sun Yu , Zheng Guo , Liu Yan Jun
Published: August 2010

The structures and properties of alkyl-phosphate potassium salts (PK) are discussed. The results showed that the particle size of the PK emulsion decreased as the pH and neutralization temperature increased. The mono/diester ratio and humidity both had considerable influence on the antistatic property of the fibers. The particle size of the PK had little influence on the antistatic property but great influence on the frictional property of the polyester staple fibers.
Study on Preparation and Properties of Copolymer of Phenol and Acrylamide by Enzyme Catalyzed Polymerization
Authors: Ma Yan Fen , Lv Sheng Hua , Liu Gang , Duan Jian Ping , Gao Rui Jun
Published: August 2010

The copolymer of phenol and acrylamide was synthesized by copolymerization using horseradish peroxidase (HRP)/H2O2 as catalyst. The effect of monomer composition on the copolymer tanning agent properties was investigated. The structure of the copolymer was characterized by Fourier transform infrared (FTIR) spectroscopy. The molecular weight was determined by gel permeation chromatography (GPC). The result shows that the average molecular weight of the copolymer is about 1900. Its molecule distribution index is much narrower. The copolymer was used as tanning agent, the result shows that the applied leather is excellent in softness and dyeing.
Effect of Solution Annealing on Microstructure and Mechanical Properties of MIM Fe-Cr-Mn-Mo-N Stainless Steels
Authors: Cui Da Wei
Published: August 2010

The influence of solution annealing on the microstructure and mechanical properties of high nitrogen Fe-Cr-Mn-Mo-N austenitic stainless steels prepared by MIM was investigated. The results show that the solution treatment can improve the microstructure and properties of the stainless steels significantly. The sintered specimens before solution annealing consist of γ-austenite and embrittling intergranular Cr2N precipitates, showing a low mechanical property. After solid solution annealing, the specimens reveal a fully austenitic structure without any intergranular nitrides, whose tensile properties are much higher than those without solution annealing, which is attributed to the elimination of the nitride precipitation along the grain boundaries and the greater amount of nitrogen retained in solid solution. A mixed mode of intergranular and dimple fracture happen to the specimens before solid solution treatment, while a completely tough fracture of dimple happen to those after solid solution treatment.
Source(s) Identification of Variance Shifts in Bivariate Process Using LS-SVM Based Pattern Recognition Model
Authors: Cheng Zhi Qiang , Ma Yi Zhong
Published: August 2010

MSPC techniques are effective tools for detecting the abnormalities of process variation. But MSPC charts do not provide the necessary information about which process variables (or subset of them) are responsible for the signal. In order to identify the process abnormality in covariance matrix of bivariate process, this article proposes a model based on LS-SVM pattern recognizer and |S| chart method, the main property of this model is to identify the assignable causes through LS-SVM pattern recognizer technique when |S| chart issue a warning signal. The simulation results indicate that the proposed model is feasible and effective. A bivariate example is presented to illustrate the application of the proposed model.
Dynamic Integrated Scheduling Algorithm of Complex Multi-Products with Identical Machines
Authors: Xie Zhi Qiang , Yang Jing , He Yu Jing , Ye Guang Jie
Published: August 2010

Aiming at the dynamic integrated scheduling problem of complex multi-products with different arriving time and identical machines, an algorithm is presented by this paper that complex multi-products can be built a virtual manufacturing tree. And the tree will be divided into many subtrees according to the subsection idea. Then these subtrees will be divided into dependent operations and independent operations. Corresponding scheduling strategy is put forward according to the features of operations and the complementarities of identical machines. For dependent operations, forward greedy rule is mainly adopted. For the independent operations, this paper mainly adopts the optimum scheduling rule. Example shows that favorable results can be obtained according to scheduling strategy adopted by this paper.
An Algorithm of Simple Multi-Product Scheduling Problem with No-Wait Constraint between Operations
Authors: Xie Zhi Qiang , Yang Jing , He Yu Jing , Li Zhi Min
Published: August 2010

Considering the simple multi-product scheduling problem that there is no-wait constraint between operations, an algorithm is presented which combines the ACPM (allied critical path method) and BFSM (best fit scheduling method) scheduling algorithm. In this algorithm the operations with no-wait constraint and finish-to-start constraint can be converted into a virtual operation. So the scheduling problem with no-wait constraint can be converted into the scheduling problem without no-wait constraint operations but with virtual operations. Then the movement and adjustment algorithm is adopted to sequence the operations which are converted into virtual operation on corresponding machines. So the problem with no-wait constraint between operations can be resolved. Example shows that the method with virtual operations and the movement and adjustment algorithm presented by this paper can be easy to realize, and favorable results can be obtained.
The Decay Resistance Properties of P. Ussuriensis Kom Lumber Impregnated with Preservative by Roller-Compression
Authors: Sun Yao Xing , Fang Gui Zhen , Liu Yi Xing
Published: August 2010

Waterborne preservative of DDAC and boride are used to impregnate P. ussuriensis Kom lumbers by roller compression under compression rates ranging from 10 percent to 50 percent. Results showed that the cranny in intervascular pit membranes appeared, and the cell wall of vessel element and fiber segment displayed drape and cranny due to roller compression. With the rise of compression rate, both the penetration depth of preservative and the retention quantity of preservative in the experimental lumber increased, while the mass loss rate decreased.The penetration depth perpendicular to the grain was more than 3.9 mm, while that parallel to the grain of wood was more than 20 mm when the compression rate was greater than or equal to 30 percent. Under the compression rate of 30 percent, the retention quantity of preservative in the experimental lumber impregnated with DDAC (thickness of 1 percent) was 8.743 kg/m3 and the mass loss rate was 14.36 percent, while those with boride (thickness of 2 percent) are 3.322kg/m3 and 9.92 percent.
Cutting Path Optimization of Pattern Pieces in Garment Automatic Cutter
Authors: Li Ying Lin , Qiu Man Liang , Yang Lian He
Published: August 2010

In view of the defect and shortage in cutting path automatic optimization of 2D pattern pieces in current garment automatic cutter, a new optimization method of computer is explored. If there is no cutting path optimization implemented by garment automatic cutter before cutting, some problems will be caused, such as too much unless travel and too long processing time. At present, both at home and abroad, the studies on automatic optimization in cutting preprocessing are relatively weak. According to the “segment cutting from left to right” feature of automatic cutter in cutting process, an algorithm which can be summarized as “segment and reducing point” was proposed. This algorithm combined with the solution of shortest path problem, its purpose is to seek for the approximate optimal solution of cutting path. The algorithm implemented through Visual C++ 6.0 programming. Used in production by enterprise shows that the program is simple to operate, and has a high compute speed. Averagely, unless travel in cutting process reduced more than 10%. It proves that the algorithm is feasible and efficient. Using this algorithm achieved the purpose of reducing unless travel, improving cutting efficiency and lowering the cost.
Cutting Force Analysis when Milling Ti-6Al-4V under Dry and Near Dry Conditions Using Coated Tungsten Carbides
Authors: Ahmad Yasir M.S. , Che Hassan C.H. , Jaharah A.G. , Norhamidi M. , Gusri A.I. , Zaid A.Y.
Published: August 2010

The effectiveness of the usage of coolant in high speed machining of highly reactive material like titanium and its alloys is still far away uncertain. For this reason, it is wiser to study the effectiveness of MQL under transient cutting speed before we go to the high speed machining. This paper discusses the effect of MQL on the machinability of Ti-6Al-4V by using PVD coated cemented carbide tools. The machinability of Ti-6Al-4V was investigated based on the effect on cutting force and the tool life. The performance of PVD coated cemented carbide tool was investigated at various cutting condition. Completely dry machining and near dry (MQL) were applied in this experiment. For near dry machining, two levels of coolant flow rate were investigated, 50 and 100 mL/H. The effectiveness of mist coolant was tested at three different levels of cutting speed, 120, 135 and 150 m/min. Application of mist coolant is more significant at cutting speed of 135 m/min. At this speed longer tool life was obtained when more coolant was applied. No significant effect of the cutting speed and coolant flow rate on the surface roughness. Surface roughness is more sensitive to the feed rate and the depth of cut. No significant effect of application of MQL on cutting force at early stage of machining. MQL seems to be more affective when tools start worn out where greater contact area between tool and work piece occur to give better lubrication effect.
Variation in Chronic Nicotinamide Treatment after Traumatic Brain Injury Can Alter Components of Functional Recovery Independent of Histological Damage
Authors: Hoane Michael R , Pierce Jeremy L , Kaufman Nicholas A. , Beare Jason E.
Published: August 2010

Previously, we have shown that the window of opportunity for nicotinamide (NAM) therapy (50 mg/kg) following cortical contusion injuries (CCI) extended to 4–8 hrs post‐CCI when administered over a six day post‐CCI interval. The purpose of the present study was to determine if a more chronic NAM treatment protocol administered following CCI would extend the current window of opportunity for effective treatment onset. Groups of rats received either unilateral CCI′s or sham procedures. Initiation of NAM therapy (50 mg/kg, ip) began at either 15‐min, 4‐hrs, 8‐hrs or 24‐hrs post‐injury. All groups received daily systemic treatments for 12 days post‐CCI at 24 hr intervals. Behavioral assessments were conducted for 28 days post injury and included: vibrissae forelimb placing, bilateral tactile adhesive removal, forelimb asymmetry task and locomotor placing testing. Behavioral analysis on both the tactile removal and locomotor placing tests showed that all NAM‐treated groups facilitated recovery of function compared to saline treatment. However, on the vibrissae‐forelimb placing and forelimb asymmetry tests only the 4‐hr and 8‐hr NAM‐treated groups were significantly different from the saline‐treated group. The lesion analysis showed that treatment with NAM out to 8 hrs post‐CCI significantly reduced the size of the injury cavity. The window of opportunity for NAM treatment is task‐dependent and in some situations can extend to 24 hrs post‐CCI. These results suggest that a long term treatment regimen of 50 mg/kg of NAM starting at the clinically relevant time points may prove efficacious in human TBI.
Therapeutic Promise and Principles: Metabotropic Glutamate Receptors
Authors: Maiese Kenneth , Chong Zhao Zhong , Shang Yan Chen , Hou Jinling
Published: August 2010

For a number of disease entities, oxidative stress becomes a significant factor in the etiology and progression of cell dysfunction and injury. Therapeutic strategies that can identify novel signal transduction pathways to ameliorate the toxic effects of oxidative stress may lead to new avenues of treatment for a spectrum of disorders that include diabetes, Alzheimer′s disease, Parkinson′s disease and immune system dysfunction. In this respect, metabotropic glutamate receptors (mGluRs) may offer exciting prospects for several disorders since these receptors can limit or prevent apoptotic cell injury as well as impact upon cellular development and function. Yet the role of mGluRs is complex in nature and may require specific mGluR modulation for a particular disease entity to maximize clinical efficacy and limit potential disability. Here we discuss the potential clinical translation of mGluRs and highlight the role of novel signal transduction pathways in the metabotropic glutamate system that may be vital for the clinical utility of mGluRs.
Nitric Oxide and Cyclic Nucleotides: Their Roles in Junction Dynamics and Spermatogenesis
Authors: Lee Nikki P. Y. , Cheng C. Yan
Published: August 2010

Spermatogenesis is a highly complicated process in which functional spermatozoa (haploid, 1n) are generated from primitive mitotic spermatogonia (diploid, 2n). This process involves the differentiation and transformation of several types of germ cells as spermatocytes and spermatids undergo meiosis and differentiation. Due to its sophistication and complexity, testis possesses intrinsic mechanisms to modulate and regulate different stages of germ cell development under the intimate and indirect cooperation with Sertoli and Leydig cells, respectively. Furthermore, developing germ cells must translocate from the basal to the apical (adluminal) compartment of the seminiferous epithelium. Thus, extensive junction restructuring must occur to assist germ cell movement. Within the seminiferous tubules, three principal types of junctions are found namely anchoring junctions, tight junctions, and gap junctions. Other less studied junctions are desmosome‐like junctions and hemidesmosome junctions. With these varieties of junction types, testes are using different regulators to monitor junction turnover. Among the uncountable junction modulators, nitric oxide (NO) is a prominent candidate due to its versatility and extensive downstream network. NO is synthesized by nitric oxide synthase (NOS). Three traditional NOS, specified as endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS), and one testis‐specific nNOS (TnNOS) are found in the testis. For these, eNOS and iNOS were recently shown to have putative junction regulation properties. More important, these two NOSs likely rely on the downstream soluble guanylyl cyclase/cGMP/protein kinase G signaling pathway to regulate the structural components at the tight junctions and adherens junctions in the testes. Apart from the involvement in junction regulation, NOS/NO also participates in controlling the levels of cytokines and hormones in the testes. On the other hand, NO is playing a unique role in modulating germ cell viability and development, and indirectly acting on some aspects of male infertility and testicular pathological conditions. Thus, NOS/NO bears an irreplaceable role in maintaining the homeostasis of the microenvironment in the seminiferous epithelium via its different downstream signaling pathways.
Endothelial Nitric Oxide Synthase Expression Is Progressively Increased in Primary Cerebral Microvascular Endothelial Cells During Hyperbaric Oxygen Exposure
Authors: Xu Xiongfei , Wang Zhongzhuang , Li Quan , Xiao Xiang , Lian Qinglin , Xu Weigang , Sun Xuejun , Tao Hengyi , Li Runping
Published: August 2010

Exposure to hyperbaric oxygen (HBO) can lead to seizures. Many studies have demonstrated that there exist a very close relationship between the alteration of cerebral blood flow (CBF) and the onset of seizures. Nitric oxide (NO) may play a key role in the change of CBF during exposure, and modulation of endothelial nitric oxide synthase (eNOS)‐derived NO by HBO is responsible for early vasoconstriction, whereas late HBO‐induced vasodilation depends upon a large amount of NO from both eNOS and neuronal nitric oxide synthase (nNOS). To investigate the effect of HBO on the activity and expression of eNOS in cerebral microvascular endothelial cells (CMEC) in vitro, primarily cultured CMEC from neonatal rats were exposed to oxygen at 500 kPa [5 atmosphere absolute (ATA)] for 10, 20, 30, 60 and 120 minutes (min), then eNOS activity, protein and mRNA contents in cells were detected. Our results showed that immediately after exposure, 30, 60 and 120 min HBO exposures did not alter NOS activity. When detected no matter immediately or six hours (h) after exposure, these exposures also did not alter eNOS protein and mRNA levels. However, when detected 24 h after exposure, 30, 60 and 120 min exposures upregulated eNOS protein content by 39%, 60% and 40% respectively. 10 and 20 min exposures upregulated eNOS mRNA content by about 15%, while 30, 60 and 120 min exposures upregulated it by about 20–30%. The increased eNOS protein and mRNA contents at 24 h after exposure may reflect new protein synthesis for eNOS. Our studies showed that with the exposing protocols we used, HBO did induce eNOS expression increase in CMEC. However, compared with the decrease of CBF in vivo, which occurred in a relative short time after rat was exposed to HBO above 4 ATA, the responses of eNOS in CMEC in vitro were a little slow. Thus we considered that for the vasodilation in the late period of HBO exposure before seizure, the effect of NO produced by eNOS was limited.
Oxidative Stress Induction of DJ‐1 Protein in Reactive Astrocytes Scavenges Free Radicals and Reduces Cell Injury
Authors: Yanagida Takashi , Tsushima Jun , Kitamura Yoshihisa , Yanagisawa Daijiro , Takata Kazuyuki , Shibaike Tomonori , Yamamoto Atsuko , Taniguchi Takashi , Yasui Hiroyuki , Taira Takahiro , Morikawa Shigehiro , Inubushi Toshihiro , Tooyama Ikuo , Ariga Hiroyoshi
Published: August 2010

Astrocytes, one of the predominant types of glial cells, function as both supportive and metabolic cells for the brain. Under cerebral ischemia/reperfusion‐induced oxidative conditions, astrocytes accumulate and activate in the ischemic region. DJ‐1 has recently been shown to be a sensor of oxidative stress in living cells. However, the function of astrocytic DJ‐1 is still unknown. In the present study, to clarify the effect of astrocytic DJ‐1 protein under massive oxidative insult, we used a focal ischemic rat model that had been subjected to middle cerebral artery occlusion (MCAO) and reperfusion. We then investigated changes in the distribution of DJ‐1 in astrocytes, DJ‐1 release from cultured astrocytes, and the effects of recombinant DJ‐1 protein on hydrogen peroxide (H2O2)‐induced death in normal and DJ‐1‐knockdown SH‐SY5Y cells and on in vitro scavenging of hydroxyl radicals (•OH) by electron spin resonance spectrometry. At 24 h after 2‐h MCAO and reperfusion, an infarct lesion was markedly observed using magnetic resonance imaging and 2,3,5‐triphenyltetrazolium chloride staining. In addition, reactive astrocytes enhanced DJ‐1 expression in the penumbral zone of the ischemic core and that DJ‐1 protein was extracellularly released from astrocytes by H2O2 in in vitro primary cultures. Although DJ‐1‐knockdown SH‐SY5Y cells were markedly vulnerable to oxidative stress, treatment with glutathione S‐transferase‐tagged recombinant human DJ‐1 protein (GST‐DJ‐1) significantly inhibited H2O2‐induced cell death. In addition, GST‐DJ‐1 protein directly scavenged •OH. These results suggest that oxidative stress induces the release of astrocytic DJ‐1 protein, which may contribute to astrocyte‐mediated neuroprotection.
Iron Toxicity: New Conditions Continue to Emerge
Authors: Weinberg Eugene D.
Published: August 2010

During the past half century, excessive/misplaced iron has been observed to be a risk factor for an increasing number and diversity of disease conditions. An extensive list of conditions and of the types of iron association were published in early 2008. Within the subsequent year, four additional disorders have been recognized to be enhanced by iron: aging muscle atrophy, viral replication, rosacea and pulmonary alveolar proteinosis. This paper adds new data and emphasis on these disorders as entities associated with increased iron load and toxicity.
Excitotoxic Insults Lead to Peroxiredoxin Hyperoxidation
Authors: Léveillé Frédéric , Soriano Francesc X. , Papadia Sofia , Hardingham Giles E.
Published: August 2010

Post‐mitotic neurons must have strong antioxidant defenses to survive the lifespan of the organism. We recently showed that neuronal antioxidant defenses are boosted by synaptic activity. Elevated synaptic activity, acting via the N‐methyl‐D‐aspartate (NMDA) receptor, enhances thioredoxin activity, facilitates the reduction of hyperoxidized peroxiredoxins, and promotes resistance to oxidative stress. In contrast, blockade of spontaneous synaptic NMDA receptor activity renders neurons highly sensitive to hyperoxidation of peroxiredoxins by oxidative insults. These NMDA receptor‐dependent effects are mediated in part by a coordinated program of gene expression changes centered on the thioredoxin‐peroxiredoxin system, a thiol‐based enzymatic system which is an important reducer of oxidative stressors such as hydroperoxides. We show here that while too little glutamatergic activity can render neurons vulnerable to peroxiredoxin hyperoxidation, so can too much. Exposure of neurons to toxic concentrations of glutamate, activating both synaptic and extrasynaptic NMDA receptors, acutely induces peroxiredoxin hyperoxidation. Thus, the effect of NMDA receptor activity on the activity of neuronal peroxiredoxins follows the classical U‐shaped dose response curve.
O‐linked β‐N‐acetylglucosamine During Hyperglycemia Exerts Both Anti‐Inflammatory and Pro‐Oxidative Properties in the Endothelial System
Authors: Rajapakse Angana Gupta , Ming Xiu-Fen , Carvas João M. , Yang Zhihong
Published: August 2010

Elevated cellular levels of protein O‐linked β‐N‐acetylglucosamine (O‐GlcNAc) through hexosamine biosynthesis pathway (HBP) are suggested to contribute to cardiovascular adverse effects under chronic hyperglycemic condition associated with oxidative stress and inflammation. Conversely, enhancing O‐GlcNAc levels have also been demonstrated being protective against myocardial ischemia/reperfusion injury. We recently demonstrated that hyperglycemia increases oxidative stress and HBP flux in endothelial cells and enhances endothelial expression of vascular adhesion molecule‐1 (VCAM‐1) and intercellular adhesion molecule‐1 (ICAM‐1) in response to tumor necrosis factor‐α (TNFα) through oxidative stress rather than HBP pathway. Here we present further complementary data showing that enhancing O‐GlcNAc levels by glucosamine does not mimic hyperglycemia′s effect on TNFα‐induced endothelial VCAM‐1 and ICAM‐1 expression. Glucosamine however inhibits ICAM‐1 (not VCAM‐1) expression and induces superoxide generation in the cells. The results further suggest that increased O‐GlcNAc levels do not mediate the enhancing effect of hyperglycemia on the endothelial inflammatory responses to TNFα. In contrast, it exerts certain anti‐inflammatory effects accompanied by pro‐oxidative properties. Further work should delineate the exact role of HPB pathway in different aspects of cardiovascular functions, especially those of diabetic cardiovascular complications.
Acute Seizure Activity Promotes Lipid Peroxidation, Increased Nitrite Levels and Adaptive Pathways Against Oxidative Stress in the Frontal Cortex and Striatum
Authors: Júnior Hélio Vitoriano Nobre , Fonteles Marta Maria de França , Mendes de Freitas Rivelilson
Published: August 2010

Previous experiments have shown that the generation of free radicals in rat brain homogenates is increased following pilocarpine‐induced seizures and status epilepticus (SE). This study was aimed at investigating the changes in neurochemical mechanisms such as lipid peroxidation levels, nitrite content, glutathione reduced (GSH) concentration, superoxide dismutase and catalase activities in the frontal cortex and the striatum of Wistar adult rats after seizures and SE induced by pilocarpine. The control group was treated with 0.9% saline and another group of rats received pilocarpine (400 mg/kg, i.p.). Both groups were sacrificed 24 h after the treatments. Lipid peroxidation level, nitrite content, GSH concentration and enzymatic activities were measured by using spectrophotometric methods. Our findings showed that pilocarpine administration and its resulting seizures and SE produced a significant increase of lipid peroxidation level in the striatum (47%) and frontal cortex (59%). Nitrite contents increased 49% and 73% in striatum and frontal cortex in pilocarpine group, respectively. In GSH concentrations were decreases of 54% and 58% in the striatum and frontal cortex in pilocarpine group, respectively. The catalase activity increased 39% and 49% in the striatum and frontal cortex, respectively. The superoxide dismutase activity was not altered in the striatum, but it was present at a 24% increase in frontal cortex. These results suggest that there is a direct relationship between the lipid peroxidation and nitrite contents during epileptic activity that can be responsible for the superoxide dismutase and catalase enzymatic activity changes observed during the establishment of seizures and SE induced by pilocarpine.
Phthalate Esters Used as Plasticizers in Packed Red Blood Cell Storage Bags May Lead to Progressive Toxin Exposure and the Release of Pro‐Inflammatory Cytokines
Authors: Rael Leonard T. , Bar-Or Raphael , Ambruso Daniel R. , Mains Charles W. , Slone Denetta S. , Craun Michael L. , Bar-Or David
Published: August 2010

Phthalate esters (PE′s) are plasticizers used to soften PVC‐based medical devices. PE′s are the most abundant man‐made pollutants and increase the risk of developing an allergic respiratory disease or a malignancy. The leaching of PE′s in donated packed red blood cells (PRBC) during storage was assessed. PRBC transfusion bags containing CPD/AS‐1 (ADSOL) buffer were analyzed. Samples were collected on storage day 1 and day 42. Two PE′s, di‐(2‐ethylhexyl) phthalate (DEHP) and mono‐(2‐ethylhexyl) phthalate (MEHP), were measured by liquid chromatography coupled to mass spectrometry (LCMS). Interleukin‐8 (IL‐8) was measured by standard ELISA techniques. DEHP significantly increased from 34.3 µM (±20.0 SD) on day 1 to 433.2 µM (±131.2 SD) on day 42, a 12.6‐fold increase. Similarly, MEHP significantly increased from 3.7 µM (±2.8 SD) on day 1 to 74.0 µM (±19.1 SD) on day 42, a 20.2‐fold increase. Also, DEHP and MEHP increased the release of IL‐8 from human umbilical vein endothelial cells (HUVEC). The transfusion of older units of PRBC could lead to an accumulation of PE′s possibly resulting in inflammation and other effects. This accumulation could be exacerbated due to the decreased metabolism of PE′s since trauma patients have a lower esterase activity, the enzymes responsible for metabolizing PE′s. The effect of oxidative stress caused by PE′s is discussed as a potential mechanism for increases in inflammation caused by older units of PRBC.
Sphingosine Protects Aging Hearts from Ischemia/Reperfusion Injury: Superiority to Sphingosine 1‐Phosphate and Ischemic Pre‐ and Post‐Conditioning
Authors: Vessey Donald A. , Kelley Michael , Li Luyi , Huang Yong
Published: August 2010

Aging hearts are known to have diminished capacity to be protected against reoxygenation ischemia/reperfusion (IR) injury provided by various cardioprotective regimens. In search of a more successful regimen, we have studied the response of aged hearts to preconditioning (PC) and postconditioning (POST) elicited by sphingosine or sphingosine 1‐phosphate treatment.

An ex vivo rat heart model was used to study the ability of PC and POST to protect old hearts (27 month) against I/R injury generated by 40 minutes (min) of index ischemia followed by 40 min of reperfusion. The response to ischemic PC was reduced in 27 month old hearts relative to 3–6 month (young) hearts as noted by a poor recovery of left ventricular developed pressure (LVDP) upon reperfusion (45% vs. 74% in young hearts) and a large infarct size after 40 min of reperfusion (37% versus 8% in young hearts). PC with sphingosine 1‐phosphate (S1P) was also poor in old hearts yielding only 49% recovery of LVDP and a 27% infarct size. In contrast, PC with sphingosine was unaffected by aging; the 78% recovery of LVDP and 8% infarct size were not different from young hearts. Ischemic POST was less affected by aging than ischemic PC, but the old hearts still experienced infarct sizes of 28%. POST of old hearts with S1P was also associated with a substantial infarct size (24%). However, POST of old hearts with sphingosine was superior to the other forms of POST in that it reduced the infarct size to 12%. S1P levels were found to be lower in old hearts which may contribute to the decreased effectiveness of ischemic PC and POST. Further, phospho‐Akt levels and distribution were altered in response to cardioprotection in the old hearts. In conclusion, POST was less affected by aging than PC; and sphingosine is a uniquely effective agent for both PC and POST of aging hearts.
Chenopodium Album Prevents Progression of Cell Growth and Enhances Cell Toxicity in Human Breast Cancer Cell Lines
Authors: Khoobchandani Menka , Ojeswi B. K. , Sharma Bhavna , Srivastava Man Mohan
Published: August 2010

The present study is aimed to investigate the effects of Chenopodium album (leaves) on the growth of estrogen dependent (MCF‐7) and estrogen independent (MDA‐MB‐468) human breast cancer cell lines. The different solvent extracts (petroleum ether, ethyl acetate and methanol) were assessed for their cytotoxicity using TBE (Trypan blue exclusion) and MTT [3‐(4, 5‐dimethyl thiazol‐2‐yl)‐2, 5‐diphenyl tetrazolium] bioassay. These cells were cultured in MEM (minimum essential medium) medium and incubated with the dilution series of extracts (10–100 mg/ml) in CO2 incubator at 37°C for 24 h. Among the various extracts studied for two cell lines, methanolic extract of C. album (leaves) exhibited maximum antibreast cancer activity having IC50 (the concentration of an individual compound leading to 50% inhibition) value 27.31 mg/ml against MCF‐7 cell line. Significant percent inhibition (94.06%) in the MeOH extract of C. album (leaves) at 48 h of exposure and concentration 100 mg/ml (p < 0.05) against MCF‐7 breast cancer cell line, indicates the presence of some structural moiety responsible for this observed antiproliferative effect. In vivo study and structural elucidation of its bioactive principle are in progress. Our findings highlight the potential of this plant for its possible clinical use to counteract malignancy development as antibreast cancer bioagent.
A Fork in the Path: Developing Therapeutic Inroads with FoxO Proteins
Authors: Maiese Kenneth , Hou Jinling , Chong Zhao Zhong , Shang Yan Chen
Published: August 2010

Advances in clinical care for disorders involving any system of the body necessitates novel therapeutic strategies that can focus upon the modulation of cellular proliferation, metabolism, inflammation and longevity. In this respect, members of the mammalian forkhead transcription factors of the O class (FoxOs) that include FoxO1, FoxO3, FoxO4 and FoxO6 are increasingly being recognized as exciting prospects for multiple disorders. These transcription factors govern development, proliferation, survival and longevity during multiple cellular environments that can involve oxidative stress. Furthermore, these transcription factors are closely integrated with several novel signal transduction pathways, such as erythropoietin and Wnt proteins, that may influence the ability of FoxOs to act as a “double‐edge sword” to sometimes promote cell survival, but at other times lead to cell injury. Here we discuss the fascinating but complex role of FoxOs during cellular injury and oxidative stress, progenitor cell development, fertility, angiogenesis, cardiovascular function, cellular metabolism and diabetes, cell longevity, immune surveillance and cancer.
Acacia Senegal Gum Exudate Offers Protection Against Cyclophosphamide‐Induced Urinary Bladder Cytotoxicity
Authors: Al-Yahya Abdulaziz A. , Al-Majed Abdulhakeem A. , Gado Ali M. , Daba Mohammad H. , Al-Shabanah Othman A. , El-Azab Adel S. , Abd-Allah Adel R. A.
Published: August 2010

Cylophosphamide (CYCL) is a strong anticancer and immunosuppressive agent but its urotoxicity presents one of the major toxic effects that limit its wide usage particularly in high dose regimens. Therefore, this study aimed to investigate Acacia Senegal gum exudate, Gum Arabic (GA), for its possible role as a natural, nontoxic agent against CYCL‐induced urotoxicity. Male Swiss albino rats were exposed to CYCL (150 mg/kg BW, once i.p) with or without GA oral supplementation (7.5 g/kg/day for 6 days) through drinking water. Glutathione (GSH), Malondialdehyde (MDA) and Nitric oxide (NO) bladder contents were assessed. Responsiveness of the bladder rings to acetylcholine (ACh) in vitro, microscopic and macroscopic features are also investigated. CYCL produced pronounced harmful effects on bladder urothelial lining with significant increases in (MDA) and NO levels in the tissue homogenates. Bladder‐GSH content is dropped by over 60% following CYCL injection. Bladder contractility, as measured by its responsiveness to ACh, recorded a marked reduction. The isolated bladders exhibited such macroscopic changes as severe edema, inflammation and extravasation. The bladder weight increased as well. Histological changes were evident in the form of severe congestion, petechial hemorrhage and chronic inflammatory reaction in the lamina propria accompanied with desquamated epithelia. GA, a potential protective agent, produced an almost complete reversal of NO induction, lipid peroxidation or cellular GSH bladder contents in the GA + CYCL‐treated group. Likewise, bladder inflammation and edema were reduced. Bladder rings showed a remarkable recovery in their responsiveness to ACh. Bladder histological examination showed a near normal configuration and structural integrity, with a significant reduction in inflammation and disappearance of focal erosions. These remarkable effects of GA may be attributed to its ability to neutralize acrolein, the reactive metabolite of CYCL and/or the resultant reactive oxygen metabolites, through a scavenging action. GA may limit the cascading events of CYCL‐induced damage, initiating a cytoprotective effect leading to structural and functional recovery of the bladder tissues.
Structural, Chemical and Biological Aspects of Antioxidants for Strategies Against Metal and Metalloid Exposure
Authors: Flora Swaran J. S.
Published: August 2010

Oxidative stress contributes to the pathophysiology of exposure to heavy metals/metalloid. Beneficial renal effects of some medications, such as chelation therapy depend at least partially on the ability to alleviate oxidative stress. The administration of various natural or synthetic antioxidants has been shown to be of benefit in the prevention and attenuation of metal induced biochemical alterations. These include vitamins, N‐acetylcysteine, α‐lipoic acid, melatonin, dietary flavonoids and many others. Human studies are limited in this regard. Under certain conditions, surprisingly, the antioxidant supplements may exhibit pro‐oxidant properties and even worsen metal induced toxic damage. To date, the evidence is insufficient to recommend antioxidant supplements in subject with exposure to metals. Prospective, controlled clinical trials on safety and effectiveness of different therapeutic antioxidant strategies either individually or in combination with chelating agent are indispensable. The present review focuses on structural, chemical and biological aspects of antioxidants particularly related to their chelating properties.
Oxidative Stress as a Mediator of Cardiovascular Disease
Authors: Elahi Maqsood M. , Kong Yu Xiang , Matata Bashir M.
Published: August 2010

During physiological processes molecules undergo chemical changes involving reducing and oxidizing reactions. A molecule with an unpaired electron can combine with a molecule capable of donating an electron. The donation of an electron is termed as oxidation whereas the gaining of an electron is called reduction. Reduction and oxidation can render the reduced molecule unstable and make it free to react with other molecules to cause damage to cellular and sub‐cellular components such as membranes, proteins and DNA. In this paper, we have discussed the formation of reactive oxidant species originating from a variety of sources such as nitric oxide (NO) synthase (NOS), xanthine oxidases (XO), the cyclooxygenases, nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase isoforms and metal‐catalyzed reactions. In addition, we present a treatise on the physiological defences such as specialized enzymes and antioxidants that maintain reduction‐oxidation (redox) balance. We have also given an account of how enzymes and antioxidants can be exhausted by the excessive production of reactive oxidant species (ROS) resulting in oxidative stress/nitrosative stress, a process that is an important mediator of cell damage. Important aspects of redox imbalance that triggers the activity of a number of signaling pathways including transcription factors activity, a process that is ubiquitous in cardiovascular disease related to ischemia/reperfusion injury have also been presented.
Intestinal Oxidative State Can Alter Nutrient and Drug Bioavailability
Authors: Ana Faria , Monteiro Rosário , Pestana Diogo , Freitas Victor De , Mateus Nuno , Azevedo Isabel , Calhau Conceição
Published: August 2010

Organic cations (OCs) are substances of endogenous (e.g., dopamine, choline) or exogenous (e.g., drugs like cimetidine) origin that are positively charged at physiological ph. since many of these compounds can not pass the cell membrane freely, their transport in or out of cells must be mediated by specific transport systems. Transport by organic cation transporters (OCTs) can be regulated rapidly by altering their trafficking and/or affinities in response to stimuli. However, for example, a specific disease could lead to modifications in the expression of OCTs. Chronic exposure to oxidative stress has been suggested to alter regulation and functional activity of proteins through several pathways. According to results from a previous work, oxidation‐reduction pathways were thought to be involved in intestinal organic cation uptake modulation. The present work was performed in order to evaluate the influence of oxidative stressors, especially glutathione, on the intestinal organic cation absorption. For this purpose, the effect of compounds with different redox potential (glutathione, an endogenous antioxidant, and procyanidins, diet antioxidants) was assessed on MPP+ (1‐methyl‐4‐phenylpyridinium iodide) uptake in an enterocyte cell line (Caco‐2). Caco‐2 cells were subcultured with two different media conditions (physiological: 5 mM glucose, referred as control cells; and high‐glucose: 25 mM glucose, referred as HG cells). In HG cells, the uptake was significantly lower than in control cells. Redox changing interventions affected Mpp+ uptake, both in control and in high‐glucose Caco‐2 cells. Cellular glutathione levels could have an important impact on membrane transporter activity. The results indicate that modifications in the cellular oxidative state modulate MPP+ uptake by Caco‐2 cells. Such modifications may reflect in changes of nutrient and drug bioavailability.