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Search Results: 1 - 10 of 9323 matches for " Ahmed Ziyyat "
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Cholesterol Depletion Disorganizes Oocyte Membrane Rafts Altering Mouse Fertilization
Jorgelina Buschiazzo, Come Ialy-Radio, Jana Auer, Jean-Philippe Wolf, Catherine Serres, Brigitte Lefèvre, Ahmed Ziyyat
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062919
Abstract: Drastic membrane reorganization occurs when mammalian sperm binds to and fuses with the oocyte membrane. Two oocyte protein families are essential for fertilization, tetraspanins and glycosylphosphatidylinositol-anchored proteins. The firsts are associated to tetraspanin-enriched microdomains and the seconds to lipid rafts. Here we report membrane raft involvement in mouse fertilization assessed by cholesterol modulation using methyl-β-cyclodextrin. Cholesterol removal induced: (1) a decrease of the fertilization rate and index; and (2) a delay in the extrusion of the second polar body. Cholesterol repletion recovered the fertilization ability of cholesterol-depleted oocytes, indicating reversibility of these effects. In vivo time-lapse analyses using fluorescent cholesterol permitted to identify the time-point at which the probe is mainly located at the plasma membrane enabling the estimation of the extent of the cholesterol depletion. We confirmed that the mouse oocyte is rich in rafts according to the presence of the raft marker lipid, ganglioside GM1 on the membrane of living oocytes and we identified the coexistence of two types of microdomains, planar rafts and caveolae-like structures, by terms of two differential rafts markers, flotillin-2 and caveolin-1, respectively. Moreover, this is the first report that shows characteristic caveolae-like invaginations in the mouse oocyte identified by electron microscopy. Raft disruption by cholesterol depletion disturbed the subcellular localization of the signal molecule c-Src and the inhibition of Src kinase proteins prevented second polar body extrusion, consistent with a role of Src-related kinases in fertilization via signaling complexes. Our data highlight the functional importance of intact membrane rafts for mouse fertilization and its dependence on cholesterol.
A New Element-Oriented Model for Computational Electromagnetics
Hamid Magrez;Abdelhak Ziyyat
PIER B , 2012, DOI: 10.2528/PIERB11050102
Abstract: In this paper, we present a new model using a Four-dimensional (4D) Element-Oriented physical concepts based on a topological approach in electromagnetism. Its general finite formulation on dual staggered grids reveals a flexible Finite-Difference Time-Domain (FDTD) method with reasonable local approximating functions. This flexible FDTD method is developed without recourse to the traditional Taylor based forms of the individual differential operators. This new formulation generalizes both the standard FDTD (S-FDTD) and the nonstandard FDTD (NS-FDTD) methods. Moreover, it can be used to generate new numerical methods. As proof, we deduce a new nonstandard scheme more accurate than the S-FDTD and the known nonstandard NS-FDTD methods. Through some numerical examples, we validate this proposal, and we show the power and the advantage of this Element-Oriented Model.
Refined Mapping of a Quantitative Trait Locus on Chromosome 1 Responsible for Mouse Embryonic Death
Magalie Vatin,Gaetan Burgio,Gilles Renault,Paul Laissue,Virginie Firlej,Fran?oise Mondon,Xavier Montagutelli,Daniel Vaiman,Catherine Serres,Ahmed Ziyyat
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043356
Abstract: Recurrent spontaneous abortion (RSA) is defined as the loss of three or more consecutive pregnancies during the first trimester of embryonic intrauterine development. This kind of human infertility is frequent among the general population since it affects 1 to 5% of women. In half of the cases the etiology remains unelucidated. In the present study, we used interspecific recombinant congenic mouse strains (IRCS) in the aim to identify genes responsible for embryonic lethality. Applying a cartographic approach using a genotype/phenotype association, we identified a minimal QTL region, of about 6 Mb on chromosome 1, responsible for a high rate of embryonic death (~30%). Genetic analysis suggests that the observed phenotype is linked to uterine dysfunction. Transcriptomic analysis of the uterine tissue revealed a preferential deregulation of genes of this region compared to the rest of the genome. Some genes from the QTL region are associated with VEGF signaling, mTOR signaling and ubiquitine/proteasome-protein degradation pathways. This work may contribute to elucidate the molecular basis of a multifactorial and complex human disorder as RSA.
Alpha6beta1 integrin expressed by sperm is determinant in mouse fertilization
Virginie Barraud-Lange, Nathalie Naud-Barriant, Line Saffar, Liliane Gattegno, Beatrice Ducot, Anne-Sophie Drillet, Morgane Bomsel, Jean-Philippe Wolf, Ahmed Ziyyat
BMC Developmental Biology , 2007, DOI: 10.1186/1471-213x-7-102
Abstract: Using Western blot analysis and immunofluorescence, we showed that the mouse sperm expresses the alpha6beta1 integrin. As for oocyte, binding of GoH3 anti-alpha6 antibody to sperm induces a specific inhibition of sperm fertilizing ability. Comparing zona-intact and zona-free eggs in fusion tests, we showed that the removal of the zona pellucida by acid treatment bypasses fertilizing oocyte alpha6beta1 integrin's function in the adhesion/fusion process.These findings show that alpha6beta1 integrin is expressed by both gametes and is functional in their membranes interaction. These results and previous reports, about fertilization of alpha6 or beta1 integrin subunits deleted oocytes by wild type sperm, suggest that the presence of alpha6beta1 integrin on one of the two gamete membranes can rescue the fertilization process. This hypothesis is further supported by the exchange of membrane fragments occurring between gametes prior to fusion that we recently reported.Sperm-egg interaction is a complex molecular process leading to gamete fusion mediated by a series of molecular interactions. Evidences have been put forward suggesting the involvement of members of the ADAMs, tetraspanins and integrins families in this mechanism. Recently, Izumo, a sperm protein belonging to the immunoglobulin superfamily, was found to be essential for the fusion [1]. Three groups reported that Cd9-deficient female mice present a dramatic reduction of their fertility due to a lack of fusion ability of their oocytes [2-4]. We recently showed that double knock-out Cd9-/-/Cd81-/- female mice are completely infertile [5] and that, upon fertilization, CD9 tetraspanin controls α6β1 integrin relocation in patches on the egg membrane [6].Integrins have also been implicated in sperm-oocyte interaction. Based on several experiments, mouse egg α6β1 integrin was described to function as a receptor of the sperm fertilin β. During further experiments, the function-blocking mAb directed against the α6 inte
The rise of diabetes prevalence in the Arab region  [PDF]
Abdesslam Boutayeb, Mohamed E. N. Lamlili, Wiam Boutayeb, Abdellatif Maamri, Abderrahim Ziyyat, Noureddine Ramdani
Open Journal of Epidemiology (OJEpi) , 2012, DOI: 10.4236/ojepi.2012.22009
Abstract: Introduction: Arab populations have many similarities and dissimilarities. They share culture, language and religion but they are also subject to economic, political and social differences. The purpose of this study is to understand the causes of the rising trend of diabetes prevalence in order to suggest efficient actions susceptible to reduce the burden of diabetes in the Arab world. Method: We use principal component analysis to illustrate similarities and differences between Arab countries according to four variables: 1) the prevalence of diabetes, 2) impaired glucose tolerance (IGT), 3) diabetes related deaths and 4) diabetes related expenditure per person. A linear regression is also used to study the correlation between human development index and diabetes prevalence. Results: Arab countries are mainly classified into three groups according to the diabetes comparative prevalence (high, medium and low) but other differences are seen in terms of diabetes-related mortality and diabetes related expenditure per person. We also investigate the correlation between the human development index (HDI) and diabetes comparative prevalence (R = 0.81). Conclusion: The alarming rising trend of diabetes prevalence in the Arab region constitutes a real challenge for heath decision makers. In order to alleviate the burden of diabetes, preventive strategies are needed, based essentially on sensitization for a more healthy diet with regular exercise but health authorities are also asked to provide populations with heath- care and early diagnosis to avoid the high burden caused by complications of diabetes.
Risk Factors and Diabetes Related Complications Frequency in the Population of the Northeastern Morocco  [PDF]
Jamila Hammoudi, Hassana Dahmani, Nourel Houda Bouanani, Hamid Nouayti, Hassane Mekhfi, Abdelkhaleq Legssyer, Mohamed Bnouham, Abderrahim Ziyyat
Open Journal of Epidemiology (OJEpi) , 2018, DOI: 10.4236/ojepi.2018.83014
Abstract: Objectives: Diabetes is one of the most challenging health problems in the 21st century that brings a considerable economic burden on worldwide healthcare resources. Indeed, people with diabetes have a higher lifetime healthcare expenditure due to the long-term complications, which include micro and macrovascular complications. This study sought to estimate the frequency of diabetes complications, and to investigate the associated risk factors. Methodology: Data were obtained from the medical records of 2401 diabetic patients followed at the Reference Center of Diabetes and Chronic Diseases (RCD) in Oujda (Morocco) during the period 2006-2011. Results: Our sample of 2401 diabetic patients include 64.7% women. 32% of patients have one or more complications; retinopathy is the most frequent complication (16.8%), followed by nephropathy (12.4%), cardiovascular diseases (5.4%), neuropathy (3.6%) and diabetes foot (2%). Logistic regression in univariate followed by multivariate analysis has showed that age, duration of diabetes and high albuminuria are the major risk factors for the development of diabetic complications in both type 1 and type 2 diabetes. Conclusions: Nearly one third of diabetic patients were affected by at least one diabetic complication; retinopathy is the most common complication in these patients. Strengthening programs to improve diabetes management and to reduce the risk of these complications should be a high priority in order to control the cost of treatment.
Least Squares Filtering Algorithm for Reactive Near Field Probe Correction
Mohammed Anisse Moutaouekkil;Abdelhak Ziyyat;Mohammed Serhir;Dominique Picard
PIER B , 2012, DOI: 10.2528/PIERB12060404
Abstract: The probe correction technique applied to reactive near field characterization is based on a deconvolution process. However, the classical deconvolution based on an inverse Fourier transform has a restrictive limitation. It is based on the use of noiseless measurement data. Consequently, measurement noise makes the result obtained by the classical deconvolution based technique inefficient and requires an extremely low noise measurement facility. In this paper, a method to improve the probe correction stability when using corrupted measurement data is presented. The proposed constrained least squares filtering algorithm (CLSF) uses an inverse filtering approach that takes into account the statistical characteristics of the measurement noise. Computations data with electromagnetic software of two different structures validate this method and illustrate its reliability.
Treatment of Chronic Lateral Epicondylitis: Platelet Rich Plasma versus Extra-Corporeal Shock Wave Therapy  [PDF]
Ahmed Mohamed Ahmed Othman
Open Journal of Orthopedics (OJO) , 2014, DOI: 10.4236/ojo.2014.43013
Abstract: Background: Several treatment options have been proposed to treat lateral epicondylitis. Both Platelet rich plasma (PRP) and Extra-corporeal Shock Wave Therapy (ESWT) are new treatment modalities for tendinopathy. Patients and Methods: Thirty seven patients suffering from chronic lateral epicondylitis (tennis elbow) for at least six months were treated in this study. The patients were divided into two treatment groups, the first group including 20 patients treated by ESWT and the second group including 17 patients treated by local injection of platelet-rich plasma. The results were evaluated using the visual analogue scale and the DASH score. Results: In the first group (treated by ESWT), the average follow-up period was 21.55 months. The average VAS improved from 8.2 to 1.95 and the average DASH score improved from 72.25 to 51.7. Moreover, 11 cases were satisfied (55%), 3 cases (15%) were satisfied with reservation and 6 cases (30%) were not satisfied. In the second group (treated by PRP), the average follow-up period was 18.47 months. The average VAS improved from 8.52 to 1.47, the DASH score improved from 72 to 48.23. Concerning patient satisfaction, 13 cases were satisfied (83.33%), 3 cases (10.52%) were satisfied with reservation and 1 case (5.55%) was not satisfied. Conclusion: Platelet rich plasma was proved to achieve superior results when compared to ESWT as regards pain relief, improvement of elbow function and patient satisfaction at follow-up.
Open versus Arthroscopic Treatment of Post-Traumatic Stiff Elbow  [PDF]
Ahmed Mohamed Ahmed Othman
Open Journal of Orthopedics (OJO) , 2014, DOI: 10.4236/ojo.2014.411047
Abstract: Thirty three patients with post-traumatic stiff elbow were divided into two groups. The first group included 18 patients with an average age of 31.05 years treated by open arthrolysis. The second included 15 patients with an average age of 31.66 years treated by arthroscopic method. The results were evaluated using the Mayo clinic score and DASH score for elbow function. In the open group, after an average period of follow-up 19.33 months, the average range of flexion-extension movement improved from 51.11° to 103.94°. The average Mayo clinic score improved from 63.38 to 92.83 and the average DASH score improved from 68.1 to 40.23. There were 13 cases (72.22%) excellent, 4 cases (22.22%) good and 1 case (5.55%) with the poor result. In the arthroscopic group, after an average period of follow-up 17.73 months, the average range of flexion-extension movement improved from 59.46° to 101.53°. The average Mayo clinic score improved from 62.93 to 92.73 and the average DASH score improved from 69.25 to 46.4. There were 10 cases (66.66%) excellent, 3 cases (20%) good and 2 cases (13.33%) with the poor result. Both open and arthro-scopic treatment can be effective in treatment of post-traumatic stiff elbow. Arthroscopic treatment is associated with less post-operative pain and morbidity. However, open treatment provides better range of motion and marked improvement of elbow function.
Energy-Efficient and Reliable Transport Protocols for Wireless Sensor Networks: State-of-Art  [PDF]
Ahmed Ayadi
Wireless Sensor Network (WSN) , 2011, DOI: 10.4236/wsn.2011.33011
Abstract: New wireless sensor network applications (e.g., military surveillance) require higher reliability than a simple best effort service could provide. Classical reliable transport protocols like Transmission Control Protocol (TCP) are not well suited for wireless sensor networks due to both the characteristics of the network nodes (low computing power, strong energy constraints) and those of the main applications running on those nodes (low data rates). Recent researches present new transport protocols for wireless sensor networks providing various type of reliability and using new mechanisms for loss detection and recovery, and congestion control. This paper presents a survey on reliable transport protocol for WSNs.
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