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Search Results: 1 - 10 of 7116 matches for " Kan Enci Mary "
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Toll-like receptor 4 mediates microglial activation and production of inflammatory mediators in neonatal rat brain following hypoxia: role of TLR4 in hypoxic microglia
Yao Linli,Kan Enci Mary,Lu Jia,Hao Aijun
Journal of Neuroinflammation , 2013, DOI: 10.1186/1742-2094-10-23
Abstract: Background Hypoxia induces microglial activation which causes damage to the developing brain. Microglia derived inflammatory mediators may contribute to this process. Toll-like receptor 4 (TLR4) has been reported to induce microglial activation and cytokines production in brain injuries; however, its role in hypoxic injury remains uncertain. We investigate here TLR4 expression and its roles in neuroinflammation in neonatal rats following hypoxic injury. Methods One day old Wistar rats were subjected to hypoxia for 2 h. Primary cultured microglia and BV-2 cells were subjected to hypoxia for different durations. TLR4 expression in microglia was determined by RT-PCR, western blot and immunofluorescence staining. Small interfering RNA (siRNA) transfection and antibody neutralization were employed to downregulate TLR4 in BV-2 and primary culture. mRNA and protein expression of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and inducible nitric oxide synthase (iNOS) was assessed. Reactive oxygen species (ROS), nitric oxide (NO) and NF-κB levels were determined by flow cytometry, colorimetric and ELISA assays respectively. Hypoxia-inducible factor-1 alpha (HIF-1α) mRNA and protein expression was quantified and where necessary, the protein expression was depleted by antibody neutralization. In vivo inhibition of TLR4 with CLI-095 injection was carried out followed by investigation of inflammatory mediators expression via double immunofluorescence staining. Results TLR4 immunofluorescence and protein expression in the corpus callosum and cerebellum in neonatal microglia were markedly enhanced post-hypoxia. In vitro, TLR4 protein expression was significantly increased in both primary microglia and BV-2 cells post-hypoxia. TLR4 neutralization in primary cultured microglia attenuated the hypoxia-induced expression of TNF-α, IL-1β and iNOS. siRNA knockdown of TLR4 reduced hypoxia-induced upregulation of TNF-α, IL-1β, iNOS, ROS and NO in BV-2 cells. TLR4 downregulation-mediated inhibition of inflammatory cytokines in primary microglia and BV-2 cells was accompanied by the suppression of NF-κB activation. Furthermore, HIF-1α antibody neutralization attenuated the increase of TLR4 expression in hypoxic BV-2 cells. TLR4 inhibition in vivo attenuated the immunoexpression of TNF-α, IL-1β and iNOS on microglia post-hypoxia. Conclusion Activated microglia TLR4 expression mediated neuroinflammation via a NF-κB signaling pathway in response to hypoxia. Hence, microglia TLR4 presents as a potential therapeutic target for neonatal hypoxia brain injurie
Low Level Primary Blast Injury in Rodent Brain
Enci Mary Kan,Eng-Ang Ling,Mui Hong Tan,Jia Lu
Frontiers in Neurology , 2011, DOI: 10.3389/fneur.2011.00019
Abstract: The incidence of blast attacks and resulting traumatic brain injuries has been on the rise in recent years. Primary blast is one of the mechanisms in which the blast wave can cause injury to the brain. The aim of this study was to investigate the effects of a single sub-lethal blast over pressure (BOP) exposure of either 48.9 kPa (7.1 psi) or 77.3 kPa (11.3 psi) to rodents in an open-field setting. Brain tissue from these rats was harvested for microarray and histopathological analyses. Gross histopathology of the brains showed that cortical neurons were “darkened” and shrunken with narrowed vasculature in the cerebral cortex day 1 after blast with signs of recovery at day 4 and day 7 after blast. TUNEL-positive cells were predominant in the white matter of the brain at day 1 after blast and double-labeling of brain tissue showed that these DNA-damaged cells were both oligodendrocytes and astrocytes but were mainly not apoptotic due to the low caspase-3 immunopositivity. There was also an increase in amyloid precursor protein immunoreactive cells in the white matter which suggests acute axonal damage. In contrast, Iba-1 staining for macrophages or microglia was not different from control post-blast. Blast exposure altered the expression of over 5786 genes in the brain which occurred mostly at day 1 and day 4 post-blast. These genes were narrowed down to 10 overlapping genes after time-course evaluation and functional analyses. These genes pointed toward signs of repair at day 4 and day 7 post-blast. Our findings suggest that the BOP levels in the study resulted in mild cellular injury to the brain as evidenced by acute neuronal, cerebrovascular, and white matter perturbations that showed signs of resolution. It is unclear whether these perturbations exist at a milder level or normalize completely and will need more investigation. Specific changes in gene expression may be further evaluated to understand the mechanism of blast-induced neurotrauma.
Notch-1 Signaling Regulates Microglia Activation via NF-κB Pathway after Hypoxic Exposure In Vivo and In Vitro
Linli Yao, Enci Mary Kan, Charanjit Kaur, S. Thameem Dheen, Aijun Hao, Jia Lu, Eng-Ang Ling
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078439
Abstract: Neuroinflammation mediated by the activated microglia is suggested to play a pivotal role in the pathogenesis of hypoxic brain injury; however, the underlying mechanism of microglia activation remains unclear. Here, we show that the canonical Notch signaling orchestrates microglia activation after hypoxic exposure which is closely associated with multiple pathological situations of the brain. Notch-1 and Delta-1 expression in primary microglia and BV-2 microglial cells was significantly elevated after hypoxia. Hypoxia-induced activation of Notch signaling was further confirmed by the concomitant increase in the expression and translocation of intracellular Notch receptor domain (NICD), together with RBP-Jκ and target gene Hes-1 expression. Chemical inhibition of Notch signaling with N-[N-(3,5-difluorophenacetyl)-1-alany1- S-phenyglycine t-butyl ester (DAPT), a γ-secretase inhibitor, effectively reduced hypoxia-induced upregulated expression of most inflammatory mediators. Notch inhibition also reduced NF-κB/p65 expression and translocation. Remarkably, Notch inhibition suppressed expression of TLR4/MyD88/TRAF6 pathways. In vivo, Notch signaling expression and activation in microglia were observed in the cerebrum of postnatal rats after hypoxic injury. Most interestingly, hypoxia-induced upregulation of NF-κB immunoexpression in microglia was prevented when the rats were given DAPT pretreatment underscoring the interrelationship between Notch signaling and NF-κB pathways. Taken together, we conclude that Notch signaling is involved in regulating microglia activation after hypoxia partly through the cross talk between TLR4/MyD88/TRAF6/NF-κB pathways. Therefore, Notch signaling may serve as a prospective target for inhibition of microglia activation known to be implicated in brain damage in the developing brain.
Honeybees-inspired heuristic algorithms for numerical optimisation
Muharrem Dü?enci
Computer Science , 2015,
Abstract: Swarm intelligence is all about developing collective behaviours to solve complex, ill-structured and large-scale problems. Efficiency in collective behaviours depends on how to harmonise the individual contributions so that a complementary collective effort can be achieved to offer a useful solution. The main points in organising the harmony remains as managing the diversification and intensification actions appropriately, where the efficiency of collective behaviours depends on blending these two actions appropriately. In this study, two swarm intelligence algorithms inspired of natural honeybee colonies have been overviewed with many respects and two new revisions and a hybrid version have been studied to improve the efficiencies in solving numerical optimisation problems, which are well-known hard benchmarks. Consequently, the revisions and especially the hybrid algorithm proposed have outperformed the two original bee algorithms in solving these very hard numerical optimisation benchmarks.
Design and Performance of Brushless Doubly-fed Machine Based on Wound Rotor with Star-polygon Structure  [PDF]
Chaohao Kan
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B015
Abstract: The star-polygon brushless doubly-fed machine (SPBDFM) is a new type of wound-rotor machine and is attractive for variable-speed constant-frequency shaft generation system. The structure of rotor for the machine may be improving the conductor availability of the rotor windings. The kirchhoff laws is employed to illuminate the principle and some combinations of different slots and poles are presented as the examples. Harmonic analysis is also employed to analyze the magnetic motive force (MMF) waveform of rotor winding with the structure of star- polygon. Finally, the results are used to reveal that the SPBDFM is attractive for shaft generation system.
Characterization of Genotypic Mutations and Antiretroviral Resistance among Viremic HIV-Infected Patients in a High HIV Prevalence Area: Treatment Challenge and Transmission Risk  [PDF]
AliAsad Arastu, Virginia Kan
World Journal of AIDS (WJA) , 2011, DOI: 10.4236/wja.2011.13011
Abstract: There have been few reports evaluating the prevalence of genotypic mutations and antiretroviral resistance among chronic HIV-infected Veterans within the United States. This retrospective cross-sectional study characterizes the rates and changes in HIV genotypic mutations and antiretroviral resistance among viremic patients from 2001 to 2006 at the VA Medical Center located in Washington, DC. The District of Columbia is the metropolitan area with the highest HIV prevalence within the United States. De-identified, linked HIV RNA, genotypic reverse transcriptase (RT) and protease (Pr) mutations and antiretroviral resistance results were assessed for changes during the 6-year period. Aggregated clinic and antiretroviral utilization, and HIV acquisition risk data were evaluated for patients in care during this time. Among 990 viremic samples, the rate of any detected RT or Pr mutation fell from 100% in 2001 to 95% in 2006. This was primarily attributable to the 15% - 20% decrease seen for RT gene mutations against nucleoside/nucleotide class and non-nucleoside class during this period. Resistance to didanosine, stavudine, zidovudine, nevirapine and efavirenz decreased, and tenofovir resistance increased. Despite stable rates of Pr gene mutations, atazanavir resistance increased by 22% from 2003 to 2006. Some but not all changes in genotypic mutations and resistance patterns reflected our patients’ antiretroviral drug utilization. As sexual contacts (77%) and injection drug use (22%) were the leading acquisition risks disclosed by our HIV-infected patients, the high prevalence and changing patterns of HIV genotypic mutations and drug resistance among these patients have had pivotal impacts not only on HIV treatment but potential transmission into our community.
An Optimization Technique for Inverse Crack Detection  [PDF]
H?kan Wirdelius
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.513121
Abstract:

Any attempts to apply techniques that are based on indirect measurements of parameters that are believed to correlate to any material properties (or state) in an in-line situation must by necessity identify a mathematical model of this relationship. The most conventional approach is to use some empirically based model. If the analysis instead is based on an analytical model of a physical explanation, this trainee period can be minimized and the system is more dynamic and less sensitive to changes within the chain of production. A numerical solution to the inverse problem of ultrasonic crack detection is in this case investigated. This solution is achieved by applying optimization techniques to a realistic model of the ultrasonic defect detection situation. This model includes a general model of an ultrasonic contact probe working as transmitter and/or receiver and its interaction with the defect. The inverse problem is reduced to minimization of a nonlinear least squares problem and is performed with a quasi-Newton algorithm consisting of a locally convergent SVD-Newton method combined with a backtracking line search algorithm. The set of synthetic data the model is fitted with are generated both by numerical integration and with the two-dimensional stationary-phase method while the forward solver in the optimization procedure is based on the latter. In both these cases, the convergence, in terms of numbers of iterations, is sufficient when the initial guess is reasonably close.

Successful Painful Treatment of the Painful Achilles Was the Start for Research Providing New Knowledge about Tendon Pain and New Treatment Methods  [PDF]
H?kan Alfredson
Pain Studies and Treatment (PST) , 2014, DOI: 10.4236/pst.2014.22013
Abstract:

Successful treatment with painful eccentric training for patients with chronic painful midportion Achilles tendinosis started research on pain mechanisms involving ultrasound + Doppler investigations and immunohistochemical analyses of tendon tissue specimens. This research has resulted in a better understanding of the pain mechanisms involved in the chronic painful Achilles and patellar tendon, and based on these findings new non tendon-invasive treatment methods beneficial for the patients have been invented. This is a mini review showing the background and research that resulted in the highly successful mini surgical treatments for mid-portion Achilles tendinopathy and proximal patellar tendinopathy.

The Relationship between Self-Directed Learning Skills and Science Achievement among Qatari Students  [PDF]
Ashraf Kan’an, Kamisah Osman
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.68082
Abstract: This study is aimed to investigate the relationship between students’ self-directed learning readiness and their science achievement. 83 students were randomly selected from a secondary school in Qatar. The students’ self-directed learning readiness was measured by the Self-Directed Learning Readiness Scale (SDLRS) and their science achievement was determined by the science subject National Exam (NE) scores. The findings of the study showed that SDLRS total score significantly predicted the National Exam science subject score (p = .049). It was suggested that self-directed learning is essential for students to be academically successful to their fullest potential. Therefore, attention should be given to possible causal factors of self-directed learning.
The Confusion and Countermeasures of Green Accounting in China  [PDF]
Xinyang Kan, Qingjun Meng
Technology and Investment (TI) , 2015, DOI: 10.4236/ti.2015.63014
Abstract: Green accounting is a new accounting field whose main function is to balance the development on both economy and environment through effective value management and combining accounting and environmental economy. Owing to the lack of relative regulation and the absence of governmental supervisory, there are some obstructions impeding its practice. In order to solve those problems, relatively well-established laws, governmental intervention and training young accountants are required in this process.
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