bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of oxygen free radicals in the serum‐mediated increase of benzoquinone genotoxicity
Authors: Fabiani Roberto , De Bartolomeo Angelo , Morozzi Guido 
Published: May 2005

AbstractThe genotoxicity of benzoquinone (BQ), a toxic benzene metabolite, is greatly enhanced by the presence of fetal calf serum (FCS) in the incubation medium. The FCS effect is abolished by heat denaturation of serum proteins and is slightly decreased by dialysis. In the present study, we have further investigated the serum effect on BQ genotoxicity by measuring DNA damage produced in peripheral blood mononuclear cells (PBMCs) using the Comet assay. We have also evaluated the effect of human serum and rat liver post‐mitochondrial fraction (S9) on the DNA damage produced by BQ. Both human serum and a rat liver S9 enhanced the genotoxicity of BQ in a manner similar to FCS. Gel filtration experiments showed that all the enhancing activity of the serum eluted with the high molecular weight fractions, suggesting that low molecular weight serum constituents do not play an important role in modulating genotoxicity. The genotoxicity‐enhancing activity of serum was inhibited by the iron chelator deferoxamine and by superoxide dismutase and catalase. Incubating PBMCs with BQ in the presence of FCS also resulted in the accumulation of intracellular peroxides as demonstrated by loading the cells with 2′,7′‐dichlorofluorescin diacetate and analyzing for peroxide formation by flow cytometry. These results indicate that oxygen free radicals are involved in the enhancement of BQ‐induced DNA damage by serum. We hypothesize that enzyme activities that reduce BQ by transferring single electrons could be the source of the oxygen free radicals. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
Substructural first‐ and second‐order model identification for structural damage assessment
Authors: Tee K. F. , Koh C. G. , Quek S. T. 
Published: May 2005

AbstractThis paper presents two methods to perform system identification at the substructural level, taking advantage of reduction in the number of unknowns and degrees of freedom (DOFs) involved, for damage assessment of fairly large structures. The first method is based on first‐order state space formulation of the substructure where the eigensystem realization algorithm (ERA) and the observer/Kalman filter identification (OKID) are used. Identification at the global level is then performed to obtain the second‐order model parameters. In the second method, identification is performed at the substructural level in both the first‐ and second‐order model identification. Both methods are illustrated using numerical simulation studies where results indicate their significantly better performance than identification using the global structure, in terms of efficiency and accuracy. A 12‐DOF system and a fairly large structural system with 50 DOFs are used where the effects of noisy data are considered. In addition to numerical simulation studies, laboratory experiments involving an eight‐storey frame model are carried out to illustrate the performance of the proposed method. The identification results presented in terms of the stiffness integrity index show that the proposed methodology is able to locate and quantify damage fairly accurately. Copyright © 2005 John Wiley & Sons, Ltd.
Microglial EP2 is critical to neurotoxicity from activated cerebral innate immunity
Authors: Shie Feng‐Shiun , Montine Kathleen S. , Breyer Richard M. , Montine Thomas J. 
Published: May 2005

AbstractProstaglandin (PG) E2 acts via four functionally antagonistic E‐prostanoid (EP) receptors that are expressed on multiple cell types in the nervous system; these are designated EP1–4. We showed previously that EP2 null mice are protected from CD14‐dependent neuronal damage in vivo following intracerebroventricular (ICV) injection of lipopolysaccharide (LPS). Clear interpretation of this neuroprotective outcome is limited because EP2 is expressed on glia and neurons. We tested the hypothesis that microglial EP2 is required for paracrine neurotoxicity following activation of innate immunity, using primary murine microglia and neuron co‐cultures. We demonstrated that microglial EP2 was necessary for lipopolysaccharide (LPS)‐activated microglia‐mediated neurotoxicity, as well as induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX‐2). Genetic deletion of microglial iNOS, pharmacological suppression of COX‐2 activity, or addition of exogenous superoxide dismutase (SOD) and catalase in the presence of EP2 also abolished neurotoxicity. This loss of paracrine neurotoxicity by EP2−/− microglia occurred in the absence of reduced cytokine levels. We conclude that microglial EP2 is critical to innate immunity‐mediated paracrine damage to neurons involving COX‐2 and iNOS. EP2 should be considered as a therapeutic target for suppression of microglial innate immunity‐mediated damage in neurodegenerative diseases. © 2005 Wiley‐Liss, Inc.
Involvement of β1 integrin in microglial chemotaxis and proliferation on fibronectin: Different regulations by ADP through PKA
Authors: Nasu‐Tada Kaoru , Koizumi Schuichi , Inoue Kazuhide 
Published: May 2005

AbstractMicroglia are immune cells in the brain; their activation, migration, and proliferation have pivotal roles in brain injuries and diseases. Microglia are known to attach firmly to fibronectin, the upregulation of which is associated with several pathological conditions in the CNS, through β1 integrin and become activated. Extracellular nucleotides can serve as potent signaling molecules. Recently, ATP and ADP were revealed to possess chemoattractive properties to microglia via Gi‐coupled P2Y receptors. In the present study, we report that the ADP‐induced chemotaxis of microglia is mediated by P2Y12/13 receptors and is β1 integrin‐dependent in the presence of fibronectin. Signals from P2Y12/13 receptors also cause β1 integrin translocation to the membrane ruffle regions, but this redistribution was lost when the intracellular cyclic AMP (cAMP) was increased by forskolin or dibutyryl cAMP. This inhibitory effect of cAMP‐elevating agents did not appear when microglia were co‐incubated with a protein kinase A (PKA) inhibitor, KT‐5720, suggesting that PKA is a negative regulator of the β1 integrin translocation. We also show that the engagement of β1 integrin enhanced microglial proliferation. Signals from P2Y12/13 receptors attenuated the proliferation, whereas ADP itself had no effect on microglial growth. Furthermore, β1 integrin‐induced proliferation is positively regulated by the cAMP‐dependent PKA. Together, these results indicate the involvement of β1 integrin in microglial proliferation and chemotaxis, both of which have clinical importance. The data also suggest that PKA is inversely involved in these two cellular functions. © 2005 Wiley‐Liss, Inc.
Interactive role of the toll‐like receptor 4 and reactive oxygen species in LPS‐induced microglia activation
Authors: Qin Liya , Li Guorong , Qian Xun , Liu Yuxin , Wu Xuefei , Liu Bin , Hong Jau‐Shyong , Block Michelle L. 
Published: May 2005

AbstractMicroglia are activated by lipopolysaccharide (LPS) to produce neurotoxic pro‐inflammatory factors and reactive oxygen species (ROS). While a multitude of LPS receptors and corresponding pathways have been identified, the detailed mechanisms mediating the microglial response to LPS are unclear. Using mice lacking a functional toll‐like receptor 4 (TLR4), we demonstrate that TLR4 and ROS work in concert to mediate microglia activation, where the contribution from each pathway is dependent on the concentration of LPS. Immunocytochemical staining of microglia in neuron–glia cultures with antibodies against F4/80 revealed that while TLR4+/+ microglia were activated the low concentration of 1 ng/ml of LPS, TLR4−/− microglia exhibit activated morphology in response to LPS only at higher concentrations (100–1,000 ng/ml). Additionally, tumor necrosis factor‐α (TNF‐α) was only produced from higher concentrations (100–1,000 ng/ml) of LPS in TLR4−/− enriched microglia cultures. Diphenylene iodonium (DPI), an inhibitor of NADPH oxidase, reduced TNF‐α production from TLR4−/− microglia. The influence of TLR4 on LPS‐induced superoxide production was tested in rat enriched microglia cultures, where the presence or absence of serum failed to show any effect on the superoxide production. Further, both TLR4−/− and TLR4+/+ microglia showed a similar increase in extracellular superoxide production when exposed to LPS (1–1,000 ng/ml). These data indicate that LPS‐induced superoxide production in microglia is independent of TLR4 and that ROS derived from the production of extracellular superoxide in microglia mediates the LPS‐induced TNF‐α response of both the TLR4‐dependent and independent pathway. © 2005 Wiley‐Liss, Inc.
Glia cell number modulates sensitivity to MPTP in mice
Authors: Smeyne Michelle , Jiao Yun , Shepherd Kennie R. , Smeyne Richard J. 
Published: May 2005

AbstractFree radical damage has been shown to play a significant role in the pathogenesis of a number of neurodegenerative diseases including Parkinson's disease. One model of experimental parkinsonism is the loss of substantia nigra cells following administration of MPTP. Previously, it has been shown that a number of inbred strains of mice have differential responses to this toxin, and this difference is dependent on glial cells. In this study, the number of glial cells in the substantia nigra pars compacta of C57Bl/6J (MPTP‐sensitive) and Swiss Webster (MPTP‐resistant) strains of mice was examined. The C57Bl/6J mice have an approximately 50% lower number of GFAP+ and S‐100β glial cells than the Swiss Webster mice. C57Bl/6J mice have a 25% increased number of resident nonactivated microglial cells. To determine whether this difference in cell number has functional significance, we used an in vitro SN culture system that allowed us to manipulate the number of glial cells. When C57Bl/6 neurons were grown on a glial mat plated with twice the number of cells, we were able to rescue the MPTP‐sensitive neurons from toxin‐induced cell death. This suggests that the number of glial cells in the SNpc may be an important factor in the survival of dopaminergic neurons following exposure to xenobiotics. © 2005 Wiley‐Liss, Inc.
Double‐stranded RNA signals antiviral and inflammatory programs and dysfunctional glutamate transport in TLR3‐expressing astrocytes
Authors: Scumpia Philip O. , Kelly Kindra M. , Reeves Westley H. , Stevens Bruce R. 
Published: May 2005

AbstractAstrocyte inflammation, reactive oxygen species (ROS) formation, and dysfunction form a common denominator shared by all the major neurodegenerative disorders. Viral infections are emerging as important events in the etiology of CNS damage involving astrocytes, but molecular understanding is incomplete. Double‐stranded RNA (dsRNA) is a byproduct of viral replication and serves as the signature molecule for viral infection via Toll‐like receptor 3 (TLR3) largely restricted to circulating peripheral dendritic cells. However, astrocytes are strategically located at the blood‐brain barrier (BBB) and throughout brain tissues, making these cells ideal candidates as innate immunity sentinels within the CNS. We hypothesized that extracellular dsRNA, mimicked by polyinosinic‐polycytidylic acid (Poly(I:C); PIC), initiates signaling of the double‐edged sword of antiviral plus pathophysiological events in astrocytes. Using Western blot analysis and real‐time qPCR, we determined that neonatal rat astrocyte cultures constitutively express TLR3 mRNA and protein, and that PIC dsRNA induced phosphorylation of eIF2α, as well as mRNA type I interferon (α/β IFN)‐response genes Mx1, PKR, and TLR3. Astrocyte TLR3 protein was downregulated after PIC treatment, however. PIC signaled degradation of IκBα with the consequence of upregulating iNOS, TNF‐α, and IL‐1β mRNAs and proteins. In addition to antiviral protection events, dsRNA induced astrocyte dysfunction, evidenced by inhibiting EAAT1/GLAST transporter gene expression and attenuating L‐glutamate uptake via sodium‐dependent transport system X, as well as inducing cytotoxicity. Anti‐TLR3 blocking antibody attenuated PIC upregulation of TNF‐α mRNA and iNOS activity. Extracellular PIC‐induced events were prevented by 2‐aminopurine, implicating PKR as an important downstream player in astrocyte dsRNA sensing pathways. The effects of plasma membrane impermeable poly(I:C) were dose‐dependent (0–50 μM). In concert, these data provide evidence that dsRNA/TLR3‐activated astrocytes initiate a battery of rapid innate pathogen‐associated molecular pattern (PAMP) immune responses that are important for mounting antiviral defense in the CNS, yet also lead to pathophysiological events associated with the glutamate neurotoxicity of neurodegenerative diseases. © 2005 Wiley‐Liss, Inc.
Caregiving burden and psychiatric morbidity in spouses of persons with mild cognitive impairment
Authors: Garand Linda , Amanda Dew Mary , Eazor Linda R. , DeKosky Steven T. , Reynolds Charles F. 
Published: May 2005

AbstractBackgroundWhile the deleterious psychosocial and mental health effects of dementia caregiving are firmly established, very little is known about the burdens or psychiatric outcomes of providing care to a spouse with less severe cognitive impairment, such as mild cognitive impairment (MCI). We characterized the nature and level of caregiver burden and psychiatric morbidity in spouses of persons diagnosed with MCI.MethodsInterview assessments were completed on a cohort of 27 spouses of persons with a recent diagnosis of MCI. Patient medical records were reviewed to collect information regarding the MCI patient's medical history.ResultsRespondents endorsed elevated levels of both task‐related responsibilities and subjective caregiver burden. Depression and anxiety symptom levels also showed some elevations. Measures of caregiver burden were significantly associated with depression and anxiety levels. In particular, even after controlling for demographic risk factors for distress, nursing task burden was correlated with elevated depressive symptoms, and greater lifestyle constraints were correlated with higher anxiety levels.ConclusionsAlthough caregiver burden and psychiatric morbidity levels were lower than those typically observed in family dementia caregiving samples, our findings suggest that MCI caregivers have already begun to experience distress in association with elevated caregiving burden. These individuals may be ideal targets for selective preventive interventions to maximize their psychological well‐being as caregiving burdens related to their spouses' cognitive impairment increase. Copyright © 2005 John Wiley & Sons, Ltd.
Why caregivers of people with dementia and memory loss don't use services
Authors: Brodaty Henry , Thomson Cathy , Thompson Claire , Fine Michael 
Published: May 2005

AbstractObjectivesTo develop a typography of the characteristics of caregivers of community dwelling people with dementia or memory loss who do not use services and empirically investigate the reasons for service non‐use.MethodThe findings of a literature review were used to develop a typography of caregivers' non‐use of services. This typography was applied to a sample of community‐based caregivers.ResultsOne in three caregivers were using no services and one in four only one service. Despite considerable proportions reporting low levels of life satisfaction and high levels of overload and resentment the main reasons caregivers gave for not using services were that they did not consider they needed the services. Other reasons for service non‐use included care recipient reluctance to use services, lack of knowledge of services or being in the process of applying for services. Service availability or affordability were not identified as major impediments to service use. Presence of a physical disability and contact with a social worker were associated with service use.ConclusionsCaregivers of people with dementia incur significant strain and have substantial need for a variety of services. Nevertheless many caregivers were not using support services, mainly because of perceived lack of need or lack of awareness. Better public promotion of services, destigmatising dementia and encouraging referrals from health professionals could help overcome the barriers to service use. Copyright © 2005 John Wiley & Sons, Ltd.
Efficacy and safety of donepezil in patients with more severe Alzheimer's disease: a subgroup analysis from a randomized, placebo‐controlled trial
Authors: Feldman Howard , Gauthier Serge , Hecker Jane , Vellas Bruno , Xu Yikang , Ieni John R. , Schwam Elias M. 
Published: May 2005

AbstractBackgroundThere have been very limited investigations of cholinesterase inhibitor therapy in more advanced stages of Alzheimer's disease (AD). The efficacy and safety of donepezil were evaluated in post hoc analyses of a subgroup of patients with more severe AD (standardized Mini‐Mental State Examination [sMMSE] score 5–12) within a randomized, placebo‐controlled trial in moderate to severe AD (MSAD study). Additional analyses examined whether donepezil's treatment effects were consistent across the full range of baseline AD severity studied (sMMSE score 5–17).MethodsPatients with moderate to severe AD (n = 290) who were living in the community or in assisted living facilities received donepezil or placebo for 24 weeks; n = 145 in the more severe AD subgroup. The primary outcome measure was the Clinician's Interview‐Based Impression of Change (CIBIC‐plus) with secondary outcomes including the sMMSE, Severe Impairment Battery, Neuropsychiatric Inventory, and Disability Assessment for Dementia. Analysis of Variance and Analysis of Covariance models tested for treatment×disease severity interaction in the full MSAD study sample.ResultsCIBIC‐plus scores for donepezil patients were significantly improved compared with placebo for each time‐point, with a 0.70 mean treatment difference at Week 24 last observation carried forward (LOCF; p = 0.0002). Significant differences favoring donepezil were noted at Week 24 LOCF for all secondary measures. There were no treatment×severity interactions for any of the efficacy measures.ConclusionsIn this analysis, donepezil had significant benefits over placebo on global, cognitive, functional, and behavioral measures in a subgroup of patients with more severe AD. Furthermore, the treatment effects of donepezil were not driven by a particular stratum within the moderate to severe dementia range. Copyright © 2005 John Wiley & Sons, Ltd.
A calcium phosphate‐based gene delivery system
Authors: Fu Huihua , Hu Yunhua , McNelis Tim , Hollinger Jeffrey O. 
Published: May 2005

AbstractAlthough nonviral vectors have lower transfection efficiency than viral vectors, the excellent safety profile of nonviral vectors is appealing for gene therapy. An efficient, simple nonviral vector gene delivery system has been designed that includes plasmid DNA–calcium phosphate precipitates (pDNA‐CaP) and porous collagen spheres (Cultispheres™). The hypothesis for this study was the pDNA‐CaP would achieve efficient plasmid DNA transfection and the porous collagen spheres would provide a suitable delivery carrier system for three‐dimensional (3D) administration. To test the hypothesis, plasmid DNA including the LacZ reporter gene encoding β‐galactosidase was precipitated with CaP to form particles of compacted LacZ‐CaP and delivered directly or by Cultispheres™ to cells in vitro. The transfection efficiency was determined by β‐galactosidase gene expression. Results indicated that pLacZ‐CaP promoted 25–84% of transfection efficiency in a broad cell line spectrum and in flexible experimental conditions. Maximum transfection efficiency was achieved by having mostly nano‐sized partles (50–200 nm in diameter) of pDNA‐CaP precipitates. Seeding density of 0.7–4 × 104 cells/cm2 provided sufficient transfection efficiency, and storage of pDNA‐CaP at 4°C was most efficient to preserve transfection efficacy for up to 3 days. The pDNA‐CaP worked well in the presence of serum and serum‐free conditions and was less cytotoxic than the liposomes. Cultispheres™ carrying plasmid LacZ‐CaP was an effective 3D system for gene delivery. The technique described here is a simple and safe procedure to deliver genes, and may have application to regenerate bone and other tissues. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
MT1‐MMP: A potent modifier of pericellular microenvironment
Authors: Itoh Yoshifumi , Seiki Motoharu 
Published: May 2005

AbstractCells are regulated by many different means, and there is more and more evidence emerging that changes in the microenvironment greatly affect cell function. MT1‐MMP is a type I transmembrane proteinase which participates in pericellular proteolysis of extracellular matrix (ECM) macromolecules. The enzyme is cellular collagenase essential for skeletal development, cancer invasion, growth, and angiogenesis. MT1‐MMP promotes cell invasion and motility by pericellular ECM degradation, shedding of CD44 and syndecan1, and by activating ERK. Thus MT1‐MMP is one of the factors that influence the cellular microenvironment and thereby affect cell‐signaling pathways and eventually alters cellular behavior. As a proteinase, MT1‐MMP is regulated by inhibitors, but it also requires formation of a homo‐oligomer complex, localization to migration front of the cells, and internalization to become a “functionally active” cell function modifier. Developing new means to inhibit “functional activity” of MT1‐MMP may be a new direction to establish treatments for the diseases that MT1‐MMP mediates such as cancer and rheumatoid arthritis. © 2005 Wiley‐Liss, Inc.
MEK hyperphosphorylation coincides with cell cycle shut down of cultured smooth muscle cells
Authors: Vogel Sabina , Kubin Thomas , von der Ahe Dietmar , Deindl Elisabeth , Schaper Wolfgang , Zimmermann René 
Published: May 2005

AbstractSmooth muscle cells (SMCs) form the backbone of arteries and their proliferation hallmarks collateral vessel growth, a process termed arteriogenesis, as well as pathogenic responses such as restenosis. Since signaling pathways in SMCs are the main targets for therapeutic interventions, we aimed to determine how and to what extent the activation of the ubiquitous MEK–ERK signaling pathway correlates with important in vivo phenomena such as dedifferentiation, nuclear activation and proliferation of SMCs. Specificity of this pathway was monitored using MEK inhibitors UO126 and PD98059 in platelet derived growth factor‐AB (PDGF‐AB)‐ and fibroblast growth factor‐2 (FGF‐2)‐stimulated SMCs. PDGF‐AB induced a rapid MEK activation followed by phosphorylation of the MEK substrates ERK1/2 while FGF‐2 showed a less pronounced and delayed activation. Both growth factors triggered a marked phosphorylation of c‐Myc and expression of Egr1. Pretreatment with MEK inhibitors suppressed the activation of the ERK cascade, abolished the down‐regulation of desmin and led to cell cycle arrest. However, the reversibility of p27Kip1 down‐regulation by UO126 was mainly observed after PDGF‐AB stimulation, indicating MEK independent p27Kip1 down‐regulation by FGF‐2. Surprisingly, treatment of SMCs with UO126 or PD98059 increased the level of MEK phosphorylation in a dose dependent manner at serine residues 217/221 in the presence as well as in the absence of both growth factors. Our results strongly imply that depending on the environmental context phosphorylation of serines 217/221 serves as an “on” as well as an “off ” switch. © 2005 Wiley‐Liss, Inc.