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Observation of interdot coupling phenomena in nanocrystalline silicon point-contact structures
M.A.H. Khalafalla,H. Mizuta,S. Oda,Z.A.K. Durrani 한국물리학회 2006 Current Applied Physics Vol.6 No.3
We have investigated the electrostatic and coherent couplings in 30 nm· 30 nm · 40 nm nanocrystalline silicon side gated point-con-tact transistors where the nanocrystalline silicon grains (1035 nm in size) formed naturally coupled quantum dots through the thin grainannealed devices showed switching of the Coulomb oscillation peaks that was associated with electrostatic coupling between two majornanocrystals embedded in the point-contact channel. We also observed in similar measurements, using an oxidised-only device, anenhanced switching of the peaks with additional peak structures in the switching region where the grains coupled strongly. The charac-teristics in this region were well tted to a sum of four Lorentzian peaks. These peaks were associated with coherent tunnelling of thebarriers.
Molecular Control of Gene Co-suppression in Transgenic Soybean via Particle Bombardment
El-Shemy, Hany A.,Khalafalla, Mutasim M.,Fujita, Kounosuke,Ishimoto, Masao Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.1
Molecular co-suppression phenomena are important to consider in transgene experiments. Embryogenic cells were obtained from immature cotyledons and engineered with two different gene constructs (pHV and pHVS) through particle bombardment. Both constructs contain a gene conferring resistance to hygromycin (hpt) as a selective marker and a modified glycinin (11S globulin) gene (V3-1) as a target. sGFP(S65T) as a reporter gene was, however, inserted into the flanking region of the V3-1 gene (pHVS). Fluorescence microscopic screening after the selection of hygromycin, identified clearly the expression of sGFP(S65T) in the transformed soybean embryos bombarded with the pHVS construct. Stable integration of the transgenes was confirmed by polymerase chain reaction (PCR) and Southern blot analysis. Seeds of transgenic plants obtained from the pHV construct frequently lacked an accumulation of endogenous glycinin, which is encoded by homologous genes to the target gene V3-1. Most of the transgenic plants expressing sGFP(S65T) showed highly accumulation of glycinin. The expression of sGFP(S65T) and V3-1 inherits into the next generations. sGFP(S65T) as a reporter gene may be useful to increase the transformation efficiency of transgenic soybean with avoiding gene co-suppression.
Concurrent Isolation of 3 Distinct Cardiac Stem Cell Populations From a Single Human Heart Biopsy
Monsanto, Megan M.,White, Kevin S.,Kim, Taeyong,Wang, Bingyan J.,Fisher, Kristina,Ilves, Kelli,Khalafalla, Farid G.,Casillas, Alexandria,Broughton, Kathleen,Mohsin, Sadia,Dembitsky, Walter P.,Sussman, Grune & Stratton 2017 Circulation research Vol.121 No.2
<P><B><U>Rationale:</U></B></P><P>The relative actions and synergism between distinct myocardial-derived stem cell populations remain obscure. Ongoing debates on optimal cell population(s) for treatment of heart failure prompted implementation of a protocol for isolation of multiple stem cell populations from a single myocardial tissue sample to develop new insights for achieving myocardial regeneration.</P><P><B><U>Objective:</U></B></P><P>Establish a robust cardiac stem cell isolation and culture protocol to consistently generate 3 distinct stem cell populations from a single human heart biopsy.</P><P><B><U>Methods and Results:</U></B></P><P>Isolation of 3 endogenous cardiac stem cell populations was performed from human heart samples routinely discarded during implantation of a left ventricular assist device. Tissue explants were mechanically minced into 1 mm<SUP>3</SUP> pieces to minimize time exposure to collagenase digestion and preserve cell viability. Centrifugation removes large cardiomyocytes and tissue debris producing a single cell suspension that is sorted using magnetic-activated cell sorting technology. Initial sorting is based on tyrosine-protein kinase Kit (c-Kit) expression that enriches for 2 c-Kit<SUP>+</SUP> cell populations yielding a mixture of cardiac progenitor cells and endothelial progenitor cells. Flowthrough c-Kit<SUP>−</SUP> mesenchymal stem cells are positively selected by surface expression of markers CD90 and CD105. After 1 week of culture, the c-Kit<SUP>+</SUP> population is further enriched by selection for a CD133<SUP>+</SUP> endothelial progenitor cell population. Persistence of respective cell surface markers in vitro is confirmed both by flow cytometry and immunocytochemistry.</P><P><B><U>Conclusions:</U></B></P><P>Three distinct cardiac cell populations with individualized phenotypic properties consistent with cardiac progenitor cells, endothelial progenitor cells, and mesenchymal stem cells can be successfully concurrently isolated and expanded from a single tissue sample derived from human heart failure patients.</P>