108 results on '"Khalifa, Ashraf"'
Search Results
102. Mutagenesis of a Copper P-Type ATPase Encoding Genein Methylococcus capsulatus (Bath) Results inCopper-Resistance
- Author
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Khalifa, Ashraf Y. Z., primary
- Published
- 2013
- Full Text
- View/download PDF
103. Design Optimization of Semi-Rigidly Connected Steel Frames Using Harmony Search Algorithm.
- Author
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Arafa, Mohammed, Khalifa, Ashraf, and Alqedra, Mamoun
- Subjects
- *
MULTIDISCIPLINARY design optimization , *STEEL framing , *FRAMING (Building) , *STRUCTURAL steel , *SEARCH algorithms - Abstract
In this paper, a design optimization algorithm is presented for non-linear steel frames with semi-rigid beam-column connections using harmony search algorithm. The design algorithm obtains the minimum steel weight by selecting from a standard set of steel sections. Strength constraints of American Institute of Steel Construction - Load and Resistance Factor Design (AISC-LRFD) specification, displacement, deflection, size constraint and lateral torsional bulking are imposed on frames. Harmony search (HS) is a recently developed meta-heuristic search algorithm which is based on the analogy between the natural musical performance and searching the solutions to optimization problems. The HS algorithm accounts for the effect of connections' flexibility and the geometric non-linearity of the members. The Frye--Morris polynomial model is used for modeling semi-rigid connections. Two design examples with extended end plate without column stiffeners are presented to demonstrate the application and validity of the algorithm. [ABSTRACT FROM AUTHOR]
- Published
- 2015
104. Enterococcus faeciumfrom chicken feces improves chicken immune response and alleviates Salmonellainfections: a pilot study
- Author
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Khalifa, Ashraf and Ibrahim, Hairul Islam Mohamed
- Abstract
Probiotics reduce the emergence of antibiotic resistance in the livestock industry. Chicken feces are reservoirs of beneficial microbiomes. The aim of this study was to isolate putative probiotics from the intestinal contents of broiler chickens. Five fecal samples were collected from two poultry farms in Al-Ahsa, Saudi Arabia. Of the 11 morphologically distinct isolates from chicken feces (CF) samples, five isolates displayed positive reactions to Gram staining, catalase, and oxidase tests, and reacted negatively to a hemolytic assay. The isolates CF1, CF2, CF3, CF8, and CF11 were selected for further analysis of probiotic characterization, gastric survival capacity, antibiotic susceptibility, and antimicrobial activity against poultry infected with Salmonella enterica. CF2 and CF11 showed the highest hydrophobic values (> 51% hydrophobic nature). CF1, CF2, and CF11 showed potent antimicrobial activities. The active isolate CF2 was identified as Enterococcus faeciumby 16s rRNA sequencing and showed a genetic similarity of 99.1%. An in vivo study was conducted using a chicken model. Enterococcus faecium-fed chickens showed an improved body weight and a lower mortality rate (17–34%). Salmonella entericacolony-forming unit (CFU) invasion in the spleen and thymus was significantly reduced in the E. faecium-fed chickens. The fecal S. entericaload was reduced from CFU 6.8 to 3.9/g in oral-administered E. faecium-fed chickens. Enterococcus faecium-fed chickens showed increased levels (P <0.01) of butyric acid and reduced levels (P< 0.01) of intestinal interleukin 1 beta, C-reactive protein, and interferon gamma levels compared to those in the S. enterica-infected chicken group. In addition, E. faeciumshowed significant binding to Caco-2 epithelial cells in vitro and inhibited S. entericacolonization, indicating co-aggregation of E. faeciumin epithelial cells. These results revealed that an E. faeciumformulation could prevent bacterial infection and improve the quality of broiler chickens.Enterococcus faeciumisolated from CF reduced the symptoms of Salmonellainfection in broiler chickens. Enterococcusis a non-toxic, beneficial bacterium that improves the health and immune response of the host.Infectious bacterial contamination in broiler production is a food safety concern and can be transmitted to humans via contaminated meat and derived products. Minimizing bacterial infections using beneficial bacteria called probiotics can reduce the emergence of antibiotic resistance in the livestock industry. In this study, we focused on improving chicken health against Salmonellainfections. Beneficial probiotics were isolated from broiler chicken carcasses. Antibiotic-sensitive and antimicrobially active beneficial bacteria were identified by DNA sequencing technology and identified as Enterococcus faecium. In a further study performed in a chicken model, E. faecium-fed chickens showed improved body weight and reduced death in Salmonella-infected chickens. The S. entericaload was also lower in these E. faecium-fed chickens. Enterococcus faecium-fed chickens showed increased levels of short-chain fatty acids and reduced interleukin 1 beta, C-reactive protein, and interferon gamma levels compared to those in the S. enterica-infected chicken group. These results revealed that an E. faeciumformulation could prevent bacterial infection and improve the quality of broiler chickens.
- Published
- 2023
- Full Text
- View/download PDF
105. Gene regulation in methanotrophs : evidence from Methylococcus capsulatus (Bath) and Methylosinus trichosporium (OB3b)
- Author
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Khalifa, Ashraf
- Subjects
QH426 - Abstract
Methylococcus capsulatus (Bath) is a Gram-negative, spherical-shaped\ud bacterium that gains its needs of carbon and energy via oxidation of methane, a\ud potent greenhouse gas, thus alleviating global warming. This bacterium oxidises\ud methane to methanol using a membrane-bound particulate methane monooxygenase\ud (pMMO) or a soluble, cytoplasmic methane monooxygenases (sMMO). Copper-tobiomass-\ud ratios significantly affect the expression and activity of both enzymes; the\ud biosynthesis of sMMO is switched on when copper-to-biomass ratios are low, while\ud pMMO is up-regulated when they are high. The exact mechanisms by which copper\ud regulates the switching between sMMO and pMMO are not fully elucidated.\ud Therefore, the main aim of this study was to shed some light on this copper switch,\ud taking the advantage of the availability of the genome sequence of this organism,\ud together with mutagenesis and transcriptional regulation studies.\ud Three potential copper transport Mc. capsulatus mutants; ΔcopA1, ΔcopA2\ud and ΔcopA3 were generated. The genes inactivated encode three different P-type\ud ATPase homologs.This revealed that CopA1, CopA2 and CopA3 have roles in\ud copper homeostasis, although disruption of genes encoding these proteins\ud individually did not result in constitutive sMMO expression.\ud In addition, three mutants; ΔnrpS-1, ΔnrpS-2 and pkS were constructed. pkS\ud encodes for a polyketide synthase, nrpS-1 and nrpS-2 encode for two non-ribosomal\ud peptide synthetases. The products of these genes were proposed to be involved in\ud biosynthesis of methanobactin, a short peptide that scavenges copper when it is\ud limited. Results suggested that nrpS-2 and pkS might be involved in production of a\ud functional methanobactin.\ud Putative coding sequences predicted to be involved in methanobactin\ud biosynthesis in another methane-oxidising bacterium, Methylosinus trichosporium\ud (OB3b), were also mutated. The mutant was unable to produce methanobactin,\ud could not express sMMO, and was copper resistant compared to the wild-type\ud organism. Therefore, methanobactin is ribosomally- produced in Ms.\ud trichosporium. Corresponding genes were not identified in the genome of Mc.\ud capsulatus.\ud A microarray-based comparative expression profiling study of whole-genome\ud transcriptomics of Mc. capsulatus expressing sMMO versus pMMO was carried out\ud to identify genes involved in regulation of MMO by copper. This identified 53 genes\ud that were differentially expressed and hence promising candidate genes for future\ud studies of MMO regulation. For example, tetR, a down-regulated gene, encodes a\ud putative transcriptional regulator and tonB, an up-regulated gene, which encodes a\ud protein that is a part of a membrane transporter. Interestingly, a cluster of six genes\ud 5’ of sMMO was up-regulated; five of them were found to be co-transcribed. A\ud mutant was made in an up-regulated gene encoding ScO protein (synthesis of\ud cytochrome c). The mutant could tolerate high concentrations of copper compared to\ud the wild-type strain.\ud The work presented in this study is considered a step forward towards\ud understanding the regulatory mechanisms of the copper switch in methanotrophs and\ud provided the basis for new lines of future research to fully understand this\ud phenomenon.
106. Nanoparticle-based flavonoid therapeutics: Pioneering biomedical applications in antioxidants, cancer treatment, cardiovascular health, neuroprotection, and cosmeceuticals.
- Author
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Morsy HM, Zaky MY, Yassin NYS, and Khalifa AYZ
- Abstract
Flavonoids, a type of natural polyphenolic molecule, have garnered significant research interest due to their ubiquitous nature and diverse biological activities, including antioxidant, anti-inflammatory, and anticancer effects, making them appealing to various scientific disciplines. In this regard, the use of a flavonoid nanoparticle delivery system is to overcome low bioavailability, bioactivity, poor aqueous solubility, systemic absorption, and intensive metabolism. Therefore, this review summarizes the classification of nanoparticles (liposomes, polymeric, and solid lipid nanoparticles) and the advantages of using nanoparticle-flavonoid formulations to boost flavonoid bioavailability. Moreover, this review illustrated the pioneering biomedical applications of nanoparticle-based flavonoid therapeutics, as well as safety and toxicity considerations of using a flavonoid nanoparticle delivery system., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)
- Published
- 2024
- Full Text
- View/download PDF
107. Investigation of the potential anti-urolithiatic activity of Alhagi maurorum (Boiss.) grown wild in Al-Ahsa (Eastern Province), Saudi Arabia.
- Author
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Ammar RB, Khalifa A, Alamer SA, Hussain SG, Hafez AM, and Rajendran P
- Subjects
- Calcium Oxalate chemistry, Calcium Oxalate urine, Humans, Saudi Arabia, Sodium Chloride, Calculi, Urolithiasis urine
- Abstract
The potential of Alhagi maurorum (Boiss.) aqueous extract (AME), used in traditional medicine for treatment or prevention of urolithiasis, to dissolve calcium oxalate stones in vitro was evaluated. In order to determine the litholytic potential of the extract, Calcium oxalate urinary stones were incubated during 12 weeks under continuous shaking in the presence of AME, Rowanix or NaCl 9 g/mL solution were used as controls. After the incubation period, the residual weight of the treated calculi was determined and the rate of dissolution was calculated. The medium pH variation was measured and changes in the calcium oxalate crystals at the stone surface were assessed using a scanning electron microscope (SEM). The results showed a significant dissolution effect for the extract on the kidney calculi during the experimentation period. At the end of the experiment, the percentages of calculi weight decrease were 41.23, 4.97 and 55.67% for the extract, NaCl solution and Rowanix, respectively. Gas Chromatography analysis revealed mainly the presence of the following phyto-compounds: Cyclopropenone, 2,3-diphenyl; 1-Nonadecanol; methyl-alpha-D-mannopyranoside; cis-9-Hexadecenal. These compounds unarguably play crucial roles in the health care system especially in cancer treatment and many other diseases including urolithiasis. The urinary stone dissolution, independent of medium pH, could be attributed to formation of complexes between the phytochemical compounds in the extract and the calculi.
- Published
- 2022
- Full Text
- View/download PDF
108. Effect of citric acid and vermi-wash on growth and metal accumulation of Sorghum bicolor cultivated in lead and nickel contaminated soil.
- Author
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Rathika R, Khalifa AYZ, Srinivasan P, Praburaman L, Kamala-Kannan S, Selvankumar T, Kim W, and Govarthanan M
- Subjects
- Antioxidants, Biomass, Chelating Agents, Chlorophyll, Citric Acid chemistry, Lead analysis, Nickel analysis, Soil chemistry, Soil Pollutants analysis, Sorghum growth & development, Biodegradation, Environmental, Lead metabolism, Nickel metabolism, Soil Pollutants metabolism, Sorghum metabolism
- Abstract
The aim of the present study is to assess the influence of vermi-wash (VW) and citric acid (CA) on Sorghum bicolor growth and phytoaccumulation of lead (Pb) and nickel (Ni) contaminated soil. The biomass of the S. bicolor has been enhanced by the addition of VW (24 and 26%) and CA (11 and 9%) in Pb and Ni contaminated soil, respectively. The VW treatment showed enhanced shoot and root lengths and chlorophyll concentrations compared to CA. The shoot anatomic structure showed an accumulation of Pb and Ni were positively impacted by the amendment of VW and CA. In addition, VW treatment showed enhanced antioxidant enzymes activity (140, 125 and 152 U/mg of CAT, SOD and POD). Further, the plants grown in Pb contaminated soil treated with VW showed enhanced Rubisco activity of 1.49 U/ml, whereas, CA treatment showed 1.23 U/ml of Rubisco. It has been observed that the VW showed as a potential chelator as well as plant beneficial formulation for the enhanced phyto-remediation of Pb and Ni., Competing Interests: Declaration of competing interest The authors declared that they dont have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Any conflict of interest in this manuscript., (Copyright © 2019 Elsevier Ltd. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
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