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Search Results: 1 - 10 of 461930 matches for " Zoheir A. Damanhouri "
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Cytotoxic Effect of Dexamethasone Restricted to Noncycling, Early G1 Phase of Melanoma Cells  [PDF]
Abdel-Moneim M. Osman, Mansour I. Sulaiman, Zoheir A. Damanhouri
Journal of Cancer Therapy (JCT) , 2011, DOI: 10.4236/jct.2011.22032
Abstract: This study deals with the inhibitory effects of dexamethsone on the proliferation of a human melanoma cells after separation into different fractions according to their position in the cell cycle using a gravity sedimentation chamber. Fractions with high percentage of G1 cells were more susceptible to the action of dexamethsone than those with a lower percentage of G1 cells. Dexamethsone stimulated the rate of incorporation of radioactive precursors into acid-precipitable materials of melanoma M-5A cells starting 24 hours after treatment for one hour. Moreover, dexamethsone treatment markedly increased the volume of the M-5A cells with increasing the possibility of stimulating the transcriptional/translational activity in the cells. This study may hopefully stimulate the development of new approaches in systemic and/or regional chemotherapy with malignant melanoma using dexamethsone with other alkylating agents to get synergestic interaction.
Modulation of doxorubicin cytotoxicity by resveratrol in a human breast cancer cell line
Abdel-Moneim M Osman, Hadeel M Bayoumi, Sameer E Al-Harthi, Zoheir A Damanhouri, Mohamed F ElShal
Cancer Cell International , 2012, DOI: 10.1186/1475-2867-12-47
Abstract: Human breast cancer cell line MCF-7, was used in this study. Cytotoxic activity of DOX was determined using (sulforhodamine) SRB method. Apoptotic cells were quantified after treatment by annexin V-FITC- propidium iodide (PI) double staining using flow-cytometer. Cell cycle disturbance and doxorubicin uptake were determined after RSVL or DOX treatment.Treatment of MCF-7 cells with 15 μg/ml RSVL either simultaneously or 24 h before DOX increased the cytotoxicity of DOX, with IC50 were 0.056 and 0.035 μg/ml, respectively compared to DOX alone IC50 (0.417 μg/ml). Moreover, flow cytometric analysis of the MCF-7 cells treated simultaneously with DOX (0.5 μg/ml) and RSVL showed enhanced arrest of the cells in G0 (80%). On the other hand, when RSVL is given 24 h before DOX although there was more increased in the cytotoxic effect of DOX against the growth of the cells, however, there was decreased in percentage arrest of cells in G0, less inhibition of DOX-induced apoptosis and reduced DOX cellular uptake into the cells.RSVL treatment increased the cytotoxic activity of DOX against the growth of human breast cancer cells when given either simultaneously or 24 h before DOX.Breast cancer is the leading cause of death in women worldwide and it is the most common cancer in the Arab world. It affects women at an early age compared with women in western countries [1]. Doxorubicin (DOX), an anthracycline antibiotic is among the most effective anticancer agents used to treat breast cancer [2]. It exerts its cytotoxic effect by intercalating between DNA base pairs on the double helix and inhibiting topoisomerase II (TOPO-II), the enzyme responsible for DNA helix conformation and stability. Unfortunately, chronic cardiotoxicity including development of a cardiomyopathy is a major limiting factor of the chemotherapeutic use of doxorubicin [3]. In an attempt to minimize DOX effective chemotherapeutic dose and thereby its side effects, a variety of approaches have been Investigated. On
A Study of Porosity Effect on Tribological Behavior of Cast Al A380M and Sintered Al 6061 Alloys  [PDF]
Avijit Sinha, Zoheir Farhat
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2015, DOI: 10.4236/jsemat.2015.51001
Abstract: Due to their light weight, high corrosion resistance and good heat conductivity, aluminium alloys are used in many industries today. They are suitable for manufacturing many automotive components such as clutch housings. These alloys can be fabricated by powder metallurgy and casting methods, in which porosity is a common feature. The presence of pores is responsible for reducing their strength, ductility and wear resistance. The present study aims to establish an understanding of the tribological behavior of high pressure die cast Al A380M and powder metallurgy synthesized Al 6061. In this study, dry sliding wear behavior of Al A380M and Al 6061 alloys was investigated under low loads (1.5 N – 5 N) against AISI 52100 bearing steel ball using a reciprocating ball-on-flat configuration and frequency of 10 Hz. Wear mechanisms were studied through microscopic examination of the wear tracks. This study revealed that due to combined effect of real area of contact and subsurface cracking, wear rate increased with increasing porosity content. The difference in friction and wear behavior between received Al A380M and Al 6061 is attributed to their hardness differences.
Effect of Surface Porosity on Tribological Properties of Sintered Pure Al and Al 6061  [PDF]
Avijit Sinha, Zoheir Farhat
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.66059
Abstract: Due to light weight, high specific strength, high corrosion resistance and good heat transfer ability, aluminium alloys are becoming attractive for critical structural applications. These alloys can be manufactured using powder metallurgy techniques in which porosity is a common characteristic. The presence of pores is responsible for decreasing effective load bearing cross sectional area and inducing stress concentration sites for strain localization and damage, decreasing both strength and ductility. The present study aims to establish a better understanding of the relationship between surface porosity and corresponding wear behavior. In this study, porous specimens were produced using powder metallurgy technique and the extent of wear damage and the type of wear was investigated under low load range of 1.5 - 5 N against AISI 52100 bearing steel ball using a reciprocating ball-on-flat configuration and frequency of 10 Hz. Scanning electron microscopy of the wear tracks and wear debris was carried out to understand wear mechanisms. This study revealed that due to combined effect of high stress intensity and subsurface cracking, wear rate increases with increasing porosity content. The friction and wear behavior of pure Al and Al 6061 as a function of porosity content can be attributed to their hardness and corresponding wear mechanism.
Wear Resistance and Indentation Behavior of Equiatomic Superelastic TiNi and 60NiTi  [PDF]
Rabin Neupane, Zoheir Farhat
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.67071
Abstract: Indentation and reciprocating wear tests are carried out to study dent and wear resistance of superelastic Ti-Ni alloys. The effect of loading rate on the superelastic behavior of TiNi under indentation loading is investigated and compared to a new generation of shape memory alloys, i.e., 60NiTi. Only limited amount of work has been done to investigate the dependency of superelasticity on loading rate of TiNi under localized compressive loads, but much work is directed towards understanding the effect of strain rate on tensile properties. Understanding the superelastic behavior helps to employ superelastic alloys in applications where high impact loading is expected as in bearings and gears. In the present study, it is found that dent resistance of Ti-Ni alloy is not significantly affected by loading rate (within the employed loading conditions). It has also been found that new-generation 60NiTi alloy exhibits superior wear and dent resistance, as well as higher hardness compared to equiatomic TiNi.
Evaluation of Plant Diversity in the Steppes of White Wormwood of the Region of Saida (Western Algeria)  [PDF]
Saidi Abdelmoumen, Mehdadi Zoheir
Open Journal of Ecology (OJE) , 2015, DOI: 10.4236/oje.2015.510040
Abstract: This work is an evaluation of the plant diversity of the white Wormwood formations (Artemisia herba-alba Asso.) in the steppes rangelands of the south-eastern zone of Sa?da (municipality of Maamora, Western Algeria). For this purpose, twenty-one phytoecological statements are carried out on three sample stations: an exclosure station where the white Wormwood is well developed and two other stations not protected where in one, the white Wormwood is moderately degraded and in the other one, it is strongly degraded. The factorial correspondences analysis (FCA) and the ascending hierarchical clustering (AHC) carried out on the floristic and edaphic parameters measured on these stations led to a hierarchy of the ecological factors determining the diversity of the studied plant formations with white Wormwood. The vegetation studied is marked by the dominance of the therophytes, particularly in the third station (very degraded station), while the exclosure station is essentially characterized by a high recovery rate and an important phytomass.
Challenging issues in molecular-targeted therapy
Zoheir Ezziane
Therapeutics and Clinical Risk Management , 2009, DOI: http://dx.doi.org/10.2147/TCRM.S4749
Abstract: llenging issues in molecular-targeted therapy Short Report (3123) Total Article Views Authors: Zoheir Ezziane Published Date March 2009 Volume 2009:5 Pages 239 - 245 DOI: http://dx.doi.org/10.2147/TCRM.S4749 Zoheir Ezziane Applied Science and Technology, Higher Colleges of Technology, Al Ain, United Arab Emirates Abstract: There are a variety of anticancer treatments including chemotherapeutic drugs, which are known to induce cell growth arrest and apoptosis through DNA damage and cytoskeleton toxicity. Meanwhile, histone deacetylase (HDAC) inhibitors could apply their antitumor activity through chromatin remodeling and gene expression modulation that affect the cell cycle and survival pathways. This paper proposes an anticancer three-drug compound and discusses several challenging issues in relation to designing multidrug compounds that could possibly lead to molecular-targeted therapies.
Analysis of the Hox epigenetic code
Zoheir Ezziane
World Journal of Clinical Oncology , 2012, DOI: 10.5306/wjco.v3.i4.48
Abstract: Archetypes of histone modifications associated with diverse chromosomal states that regulate access to DNA are leading the hypothesis of the histone code (or epigenetic code). However, it is still not evident how these post-translational modifications of histone tails lead to changes in chromatin structure. Histone modifications are able to activate and/or inactivate several genes and can be transmitted to next generation cells due to an epigenetic memory. The challenging issue is to identify or “decrypt” the code used to transmit these modifications to descent cells. Here, an attempt is made to describe how histone modifications operate as part of histone code that stipulates patterns of gene expression. This papers emphasizes particularly on the correlation between histone modifications and patterns of Hox gene expression in Caenorhabditis elegans. This work serves as an example to illustrate the power of the epigenetic machinery and its use in drug design and discovery.
Single Boson Images Via an Extended Holstein Primakoff Mapping
Zoheir Aouissat
Physics , 1999, DOI: 10.1103/PhysRevC.62.012201
Abstract: The Holstein-Primakoff mapping for pairs of bosons is extended in order to accommodate single boson mapping. The proposed extension allows a variety of applications and especially puts the formalism at finite temperature on firm grounds. The new mapping is applied to the O(N+1) anharmonic oscillator with global symmetry broken down to O(N). It is explicitly demonstrated that N-Goldstone modes appear. This result generalizes the Holstein-Primakoff mapping for interacting boson as developed in ref.[1].
Symmetry Conserving Dynamical Mappings
Zoheir Aouissat
Physics , 1999, DOI: 10.1016/S0375-9474(98)00518-1
Abstract: Using the concept of dynamical mappings, two symmetry conserving nonperturbative approaches are presented. The first is based on the 1/N-expansion and sorted out using Holstein-Primakoff mapping. The second consists of dynamically mapping the canonical fields into the corresponding currents. It is argued, either by comparing the Fock spaces or the observables, that the latter constitutes a higher approach which transcends the 1/N-expansion and contains the dynamics generated by the Gaussian functional approach.
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