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Search Results: 1 - 10 of 17 matches for " Zahia Hamidouche "
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Crosstalks between integrin alpha 5 and IGF2/IGFBP2 signalling trigger human bone marrow-derived mesenchymal stromal osteogenic differentiation
Zahia Hamidouche, Olivia Fromigué, Jochen Ringe, Thomas H?upl, Pierre J Marie
BMC Cell Biology , 2010, DOI: 10.1186/1471-2121-11-44
Abstract: Microarray analysis and validation experiments showed that the expression of IGF2 and IGFBP2 was increased together with integrin alpha5 (ITGA5) during dexamethasone-induced osteoblast differentiation in human MSCs. This effect was functional since we found that IGF2 and IGFBP2 enhanced the expression of osteoblast phenotypic markers and in vitro osteogenic capacity of hMSCs. Interestingly, we showed that downregulation of endogenous ITGA5 using specific shRNA decreased IGF2 and IGFBP2 expression in hMSCs. Conversely, ITGA5 overexpression upregulated IGF2 and IGFBP2 expression in hMSCs, which indicates tight crosstalks between these molecules. Consistent with this concept, activation of endogenous ITGA5 using a specific antibody that primes the integrin, or a peptide that specifically activates ITGA5 increased IGF2 and IGFBP2 expression in hMSCs. Finally, we showed that pharmacological inhibition of FAK/ERK1/2-MAPKs or PI3K signalling pathways that are enhanced by ITGA5 activation, blunted IGF2 and IGFBP2 expression in hMSCs.The results show that ITGA5 is a key mediator of IGF2 and IGFBP2 expression that promotes osteoblast differentiation in human MSCs, and reveal that crosstalks between ITGA5 and IGF2/IGFBP2 signalling are important mechanisms that trigger osteogenic differentiation in human bone marrow derived mesenchymal stromal cells.Mesenchymal stromal cells (MSCs) can differentiate into chondroblasts, adipocytes or osteoblasts under appropriate stimulation [1-3]. Adult human MSCs (hMSCs) are therefore an important source for tissue repair and therapy in regenerative medicine [4,5]. Expanding the osteogenic capacity of hMSCs is thus of major interest for improving the osteogenic potential of hMSCs for optimal bone regeneration [6]. The osteogenic differentiation of MSCs is characterized by the expression of timely expressed genes such as Runx2, alkaline phosphatase (ALP) and type I collagen (Col1A1) followed by extracellular matrix mineralization [7,8]. Severa
Aperture Synthesis Imaging of V892 Tau and PV Cep: Disk Evolution
Murad Hamidouche
Physics , 2010, DOI: 10.1088/0004-637X/722/1/204
Abstract: I present a study of two Herbig Ae stars that are in completely different evolutionary stages: V892 Tau and PV Cep. Using sub arc-second interferometric observations obtained with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at the 1.3 and 2.7 mm wavelengths, I have for the first time resolved their disks. I deduce that the 5 Myr old V892 Tau has a low dust opacity index $\beta$=1.1 and a disk mass of 0.03 $\msun$. These values correspond to the growth of its dust into large up to centimeters size structures. In contrast, the very young (a few 10$^5$yrs) PV Cep has a quite high opacity index $\beta$ =1.75 and a more massive disk 0.8 $\msun$. PV Cep has the youngest resolved disk around any Herbig Ae star. Unlike the youngest T Tauri and Class 0 stars, which contain large and processed grains, the young Herbig Ae star, PV Cep, disk contains ISM-like unprocessed dust. This suggests that PV Cep's dust evolution is slower than T Tauri stars'. I also present high spatial resolution interferometric observations of the PV Cep outflow. The outflow inclination is consistent with the orientation of the known Herbig-Haro flow in that region, HH315.
Study of Renal Toxicity in Wistar Rats Following the Action of Amphotericin B Solution Prepared under Extreme pH Conditions  [PDF]
Lamia Belkherroubi-Sari, Zahia Boucherit, Kebir Boucherit, Slimane Belbraouet
Food and Nutrition Sciences (FNS) , 2011, DOI: 10.4236/fns.2011.27100
Abstract: Our study related to the renal toxicity of Wistar rats induced by solutions of amphotericin B prepared under extreme conditions of pH (5.4 and 10.8). The results obtained show that with pH 5.4 of stock solution, urea and creatinin rate blood is not disturbed. These means that the renal function is not deteriorated by the amphotericin B. Furthers, treatment of animals infected by the yeast Candida albicans, with the solution of amphotericin B prepared at pH 5.4 and injected at 0.5 mg of AmB/Kg every 24 hours, seems to be effective.
A Chandra Census of C2D YSOS: Evolution of X-ray Emission
M. Hamidouche,M. Jacobson,L. W. Looney
Physics , 2010,
Abstract: We present an analytical study of a large sample of ~109 young stellar objects in the X-ray. Our objects were detected in X-ray independent of age. Unexpectedly, the X-ray energy is somewhat correlated with the ages. It decreases with time and with column density, while it should increase. We conclude that the youngest protostars, Class 0/I, emit X-rays in the 1-8 keV band. The deeply embedded sources with the strongest accretion activity are detected in the hard-band (> 2keV) only. Due to extinction, their soft X-rays are not detected. To explain the decline in energy, we suggest that within a timescale of few Myrs the corona cools down via the accretion material.
Many-to-Many Matching Games for Proactive Social-Caching in Wireless Small Cell Networks
Kenza Hamidouche,Walid Saad,Mérouane Debbah
Computer Science , 2014,
Abstract: In this paper, we address the caching problem in small cell networks from a game theoretic point of view. In particular, we formulate the caching problem as a many-to-many matching game between small base stations and service providers' servers. The servers store a set of videos and aim to cache these videos at the small base stations in order to reduce the experienced delay by the end-users. On the other hand, small base stations cache the videos according to their local popularity, so as to reduce the load on the backhaul links. We propose a new matching algorithm for the many-to-many problem and prove that it reaches a pairwise stable outcome. Simulation results show that the number of satisfied requests by the small base stations in the proposed caching algorithm can reach up to three times the satisfaction of a random caching policy. Moreover, the expected download time of all the videos can be reduced significantly.
Influence of upstream flow characteristics on the reattachment phenomenon in shallow cavities
Madi Arous Fatima,Mataoui Amina,Bouahmed Zahia
Thermal Science , 2011, DOI: 10.2298/tsci101203019m
Abstract: The influence of the upstream flow characteristics on the behavior of the flow over a shallow cavity and on the reattachment phenomenon is examined in this paper. Accordingly, a comparison of the cavity’s flow structure is performed for two different upstream flows: the wall jet flow and the boundary layer flow. The wall jet possesses a particular structure with two regions: an inner layer analogous to that of a boundary layer and an outer layer similar to that of a free jet; this layer is an additional source of turbulence production in addition to that of the inner shear layer. The present study interested to the effect of this external layer on the shallow cavity’s flow. The numerical approach is based on the low Reynolds stress-omega turbulence model. Fluent 6.3 and the pre-processor Gambit 2.3 are used for the computation. The numerical results indicate that the flow structure is very sensitive to the upstream flow’s characteristics. Indeed, for the same Reynolds number and the same boundary layer thickness at the cavity leading edge, the cavity flow structure in a wall jet upstream flow case differs considerably from that of a boundary layer upstream flow. The most important finding is the earlier reattachment process in the wall jet inflow case, where an important reduction of the reattachment length is observed compared to that of a cavity under a boundary layer flow.
Ceramics-Silikáty , 2011,
Abstract: Comparatively to the as received soda lime glass samples, the strength distribution after thermal shocks showed the appearance of a second branch in the Weibull curves. This branch is observed for temperature differences (ΔT) equal or higher than the critical temperature difference (ΔTc) for both water and motor oil cooling baths. The dispersion is more spread out in these two baths in comparison with the olive oil bath probably because of more pronounced slow crack growth effect. The Weibull modulus varies according to the used cooling bath and the considered temperature difference. In the case of thermal shock caused by air blast cooling at T = 20°C, a bimodal distribution is observed for only the critical state. The initial cracking time, obtained by acoustic emission, corresponds to the unstable propagation of the most critical defect. The number of cracks induced by thermal shock is proportional to the number of acoustic events.
Stratospheric Observatory for Infrared Astronomy
M. Hamidouche,E. Young,P. Marcum,A. Krabbe
Physics , 2010,
Abstract: We present one of the new generations of observatories, the Stratospheric Observatory For Infrared Astronomy (SOFIA). This is an airborne observatory consisting of a 2.7-m telescope mounted on a modified Boeing B747-SP airplane. Flying at an up to 45,000 ft (14 km) altitude, SOFIA will observe above more than 99 percent of the Earth's atmospheric water vapor allowing observations in the normally obscured far-infrared. We outline the observatory capabilities and goals. The first-generation science instruments flying on board SOFIA and their main astronomical goals are also presented.
A sub-millimeter Mapping Survey of Herbig AeBe Stars
G?ran Sandell,David A. Weintraub,Murad Hamidouche
Physics , 2010, DOI: 10.1088/0004-637X/727/1/26
Abstract: We have acquired sub-millimeter observations of 33 fields containing 37 Herbig Ae/Be (HAEBE) stars or potential HAEBE stars, including SCUBA maps of all but two of these stars. Nine target stars show extended dust emission. The other 18 are unresolved, suggesting that the dust envelopes or disks around these stars are less than a few arcseconds in angular size. In several cases we find that the strongest sub-millimeter emission originates from younger, heavily embedded sources rather than from the HAEBE star, which means that previous models must be viewed with caution. These new data, in combination with far-infrared flux measurements available in the literature, yield SEDs from far-infrared to millimeter wavelengths for all the observed objects. Isothermal fits to these SEDs demonstrate excellent fits, in most cases, to the flux densities longward of 100 {\mu}m. We find that a smaller proportion of B-type stars than A and F-type stars are surrounded by circumstellar disks, suggesting that disks around B stars dissipate on shorter time scales than those around later spectral types. Our models also reveal that the mass of the circumstellar material and the value of beta are correlated, with low masses corresponding to low values of beta. Since low values of beta imply large grain sizes, our results suggest that a large fraction of the mass in low-beta sources is locked up in very large grains. Several of the isolated HAEBE stars have disks with very flat sub-millimeter SEDs. These disks may be on the verge of forming planetary systems.
Flavonols and Antioxidant Activity of Ammi visnaga L. (Apiaceae)
Reguia Bencheraiet,Habiba Kherrab,Ahmed Kabouche,Zahia Kabouche
Records of Natural Products , 2011,
Abstract: Eleven flavonols have been isolated from the aerial parts of Ammi visnaga L. from which four aglycones, four monoglycosides, two diglycosides and one triglycoside. The flavonoid aglycones were distributed into one hydroxylated, quercetin (1) and three methoxylated, namely, rhamnetin (2), isorhamnetin (3) and rhamnazin (4). Among the monoglycosides, we found three 3-O-glucosides respectively linked to rhamnetin (5), isorhamnetin (6) and rhamnazin (7) and one 7-O-glucoside of isorhamnetin (8). The two diglycosides were 3-O-rutin of quercetin (9) and isorhamnetin (10) while the single trioside was quercetin 7,3,3’-O-triglucoside (11). These flavonols are reported for the first time from A. visnaga L . Free radical DPPH scavenging potential of the butanolic extract was investigated.
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