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排序方式: 共有163条查询结果,搜索用时 0 毫秒
41.
M. Z. A. Rafiquee Masoom R. Siddiqui Mohd Sajid Ali Hamad A. Al-Lohedan Z. A. Al-Othman 《Bioprocess and biosystems engineering》2015,38(4):711-719
The present paper describes about the easy, simple and convenient procedure for the synthesis of silver nanoparticles (Ag-NPs) in aqueous solutions by the reduction of silver nitrate with adrenaline. The surfactant molecules of cetyltrimethylammonium bromide (CTABr) and sodium dodecyl ate (SDS) behaved differently during the reduction of Ag+ ions by adrenaline. The obtained data suggest that the variation of [CTABr] gave a maxima-like curve for rate constant versus [CTABr], while, the values of rate constant decreased with the increase in [SDS]. The addition of surfactant molecules stabilized the Ag-NPs. The UV–Visible spectra were analyzed to deduce the particle size. The calculated sizes of the nanoparticles were further compared by the TEM images. The XRD spectrum confirmed the crystalline nature of silver nanoparticles having the face-centered cubic crystal structure. The edge length of unit cell was found 4.076 Å. The kinetics of formation of Ag-NPs was performed at different concentrations of adrenaline, AgNO3, NaOH and [surfactant]. The values of rate constant were independent on [adrenaline] and [AgNO3]. The increase in [NaOH] increased the rate of agglomeration of silver particles to form Ag-NPs. A linear relationship was obtained for the plot of rate constant versus [NaOH]. 相似文献
42.
Semian Karaer Cagatay Tarhan Murat Pekmez Ismail Hamad Nazli Arda Aysegul Topal Sarikaya 《Biochemical genetics》2010,48(1-2):113-124
Cu,Zn superoxide dismutase (SOD1) is an antioxidant enzyme that catalyzes the removal of superoxide radicals generated in various biological oxidations. Amyotrophic lateral sclerosis (ALS) is one of the most common neurodegenerative disorders, occurring in families (FALS) and sporadically (SALS). FALS and SALS are distinguishable genetically but not clinically. More than 100 point mutations in the human SOD 1 gene have been identified that cause FALS. In order to determine the effects of mutant SOD protein, we first cloned wild-type and A4V mutant human SOD1 into Schizosaccharomyces pombe. This study shows viabilities and some antioxidant properties including SOD, catalase, proteasomal activity, and protein carbonyl levels of transformants in SOD1 deleted strain (MN415); and its parental strain (JY741) at different stress conditions. There was no more oxidative damage in the human mutant SOD carrying the transformant strain compared with other strains. These results may help to explain whether ALS progresses as a consequence of cellular oxidative damage. 相似文献
43.
Cell transplantation is a promising new modality in treating damaged myocardium after myocardial infarction and in preventing postmyocardial infarction LV remodelling. Two strategies are plausible: the first uses adult tissue stem cells to replace the scar tissues and amend the lost myocardium, whilst the second strategy uses embryonic stem cells in an attempt to regenerate myocardium and/or blood vessels. 相似文献
44.
B220+ double-negative T cells suppress polyclonal T cell activation by a Fas-independent mechanism that involves inhibition of IL-2 production 总被引:4,自引:0,他引:4
Hamad AR Mohamood AS Trujillo CJ Huang CT Yuan E Schneck JP 《Journal of immunology (Baltimore, Md. : 1950)》2003,171(5):2421-2426
Fas-mediated apoptosis is a key mechanism for elimination of autoreactive T cells, yet loss of function mutations in the Fas signaling pathway does not result in overt T cell-mediated autoimmunity. Furthermore, mice and humans with homozygous Fas(lpr) or Fas ligand(gld) mutations develop significant numbers of B220+ CD4- CD8- double-negative (DN) alphabeta T cells (hereafter referred to as B220+ DN T cells) of poorly understood function. In this study, we show that B220+ DN T cells, whether generated in vitro or isolated from mutant mice, can suppress the ability of activated T cells to proliferate or produce IL-2, IL-10, and IFN-gamma. B220+ DN T cells that were isolated from either lpr or gld mice were able to suppress proliferation of autologous and syngeneic CD4 T cells, showing that suppression is Fas independent. Furthermore, restoration of Fas/Fas ligand interaction did not enhance suppression. The mechanism of suppression involves inhibition of IL-2 production and its high affinity IL-2R alpha-chain (CD25). Suppression also requires cell/cell contact and TCR activation of B220+ DN T cells, but not soluble cytokines. These findings suggest that B220+ DN T cells may be involved in controlling autoreactive T cells in the absence of Fas-mediated peripheral tolerance. 相似文献
45.
Reda F. M. Elshaarawy Hamad H. Abdel Gawad Hassan M. A. Hassan Reda M. Abd Alaal Eman M. Hassan Rana O. Yahya Lamia A. Ismail 《化学与生物多样性》2023,20(4):e202300152
A new chelating task-specific ionic liquid (TSIL), lutidinium-based salicylaldoxime ( LSOH ), and its square pyramidal vanadyl(II) complex (VO(LSO)2) have been successfully synthesized and structurally characterized using elemental (CHN), spectral, and thermal analyses. The catalytic activity of the lutidinium-salicylaldoxime complex (VO(LSO)2) in the alkene epoxidation reactions was studied under various reaction conditions, such as solvent effect, alkene/oxidant molar ratio, pH, reaction temperature, reaction time, and the catalyst dose. The results demonstrated that the CHCl3 solvent, 1 : 3 of the cyclohexene/H2O2 ratio, pH 8, temperature of 340 K, and catalyst dose of 0.012 mmol are assigned as the optimum conditions for achieving maximum catalytic activity for VO(LSO)2. Moreover, the VO(LSO)2 complex has the potential for application in the effective and selective epoxidation of alkenes. Notably, under optimal VO(LSO)2 conditions, cyclic alkenes convert more efficiently to their corresponding epoxides than linear alkenes. 相似文献
46.
The present study is concerned with the selection of economically available agricultural starchy substrate for the production of alpha amylase by Bacillus licheniformis. Different agricultural starchy substrates such as soluble starch, hordium, pearl millet, rice, corn, gram and wheat starch were tested for the production of alpha amylase by parental and its mutant derivatives. The production of alpha amylase was 10-folds better by the mutant strain B. licheniformis GCUCM-30 than the parental strain when pearl millet starch at 1.5% level and nutrient broth concentrations at the level of 0.25% was supplemented to the fermentation medium. 相似文献
47.
48.
Lumican is an extracellular protein that associates with CD14 on the surface of macrophages and neutrophils, and promotes CD14-TLR4 mediated response to bacterial lipopolysaccharides (LPS). Lumican-deficient (Lum
−/−) mice and macrophages are impaired in TLR4 signals; raising the possibility that lumican may regulate host response to live bacterial infections. In a recent study we showed that in
vitro Lum
−/− macrophages are impaired in phagocytosis of gram-negative bacteria and in a lung infection model the Lum
−/− mice showed poor survival. The cornea is an immune privileged barrier tissue that relies primarily on innate immunity to protect against ocular infections. Lumican is a major component of the cornea, yet its role in counteracting live bacteria in the cornea remains poorly understood. Here we investigated Pseudomonas aeruginosa infections of the cornea in Lum
−/− mice. By flow cytometry we found that 24 hours after infection macrophage and neutrophil counts were lower in the cornea of Lum
−/− mice compared to wild types. Infected Lum
−/− corneas showed lower levels of the leukocyte chemoattractant CXCL1 by 24–48 hours of infection, and increased bacterial counts up to 5 days after infection, compared to Lum+/− mice. The pro-inflammatory cytokine TNF-α was comparably low 24 hours after infection, but significantly higher in the Lum
−/− compared to Lum
+/− infected corneas by 2–5 days after infection. Taken together, the results indicate that lumican facilitates development of an innate immune response at the earlier stages of infection and lumican deficiency leads to poor bacterial clearance and resolution of corneal inflammation at a later stage. 相似文献
49.
50.
Musthafa Chalikandy Peedikayil Fahad Ibrahim AlSohaibani Abdullah Hamad Alkhenizan 《PloS one》2014,9(1)