49 research outputs found
Development of MAPC derived induced endodermal progenitors: Generation of pancreatic beta cells and hepatocytes
No full textMultipotent Adult Progenitor Cells (MAPCs) are one potential stem cell source to generate functional hepatocytes or β-cells. However, human MAPCs have less plasticity than pluripotent stem cells (PSCs), as their ability to generate endodermal cells is not robust. Here we studied the role of 14 transcription factors (TFs) in reprogramming MAPCs to induced endodermal progenitor cells (iENDO cells), defined as cells that can be long-term expanded and differentiated to both hepatocyte- and endocrine pancreatic-like cells. We demonstrated that 14 TF-iENDO cells can be expanded for at least 20 passages, differentiate spontaneously to hepatocyte-, endocrine pancreatic-, gut tube-like cells as well as endodermal tumor formation when grafted in immunodeficient mice. Furthermore, iENDO cells can be differentiated in vitro into hepatocyte- and endocrine pancreatic-like cells. However, the pluripotency TF OCT4, which is not silenced in iENDO cells, may contribute to the incomplete differentiation to mature cells in vitro and to endodermal tumor formation in vivo. Nevertheless, the studies presented here provide evidence that reprogramming of adult stem cells to an endodermal intermediate progenitor, which can be expanded and differentiate to multiple endodermal cell types, might be a valid alternative for the use of PSCs for creation of endodermal cell types. Reprogramming can occur by the introduction of key transcription factors (TFs) as well as by epigenetic changes. We demonstrated that histone deacetylase inhibitor (HDACi) Trichostatin A (TSA) combined with a chromatin remodeling medium (CRM) induced expression of a number of definitive endoderm and early and late pancreatic marker genes. When CRM was omitted, endoderm/pancreatic marker genes were not induced. Furthermore, treatment with DNA methyltransferase inhibitor (DNMTi) 5-azacytidine (5AZA) CRM did not affect gene expression changes, and when 5AZA was combined with TSA, no further increase in gene expression of endoderm, pancreatic endoderm, and endocrine markers was seen over levels induced with TSA alone. Interestingly, TSA-CRM did not affect expression of pluripotency and hepatocyte genes but induced some mesoderm transcripts. Upon removal of TSA-CRM, the endoderm/pancreatic gene expression profile returned to baseline. Our findings underscore the role epigenetic modification in transdifferentiation of one somatic cell into another. However, full reprogramming of fibroblasts to β-cells will require combination of this approach with TF overexpression and/or culture of the partially reprogrammed cells under -cell specific conditions
A Simple Technique for the Precise Establishment of the Working Gap in an Electrochemical Discharge Machining Process and Some Experimental Results Thereof
No full textThe working gap (Wg) between a tooltip and a substrate surface is a critical process parameter affecting the quality metrics and precision of microstructures fabricated using an electrochemical discharge machining (ECDM) process. Despite the extensive investigation carried out on ECDM processes for the last several years, only a few researchers have explicitly explained the technique used to establish the Wg. In the present work, the authors propose a simple, cost-effective technique using a commercially available metallic feeler gauge and a multimeter to precisely establish a Wg in an ECDM process. A systematic experimental investigation was carried out using the proposed method to study the influence of Wg on the quality metrics such as the depth, width, edge linearity, heat-affected zone, and surface finish of fabricated microstructures on a glass substrate. Experimental results revealed that even a 2 µm difference in Wg significantly influenced the quality and quantity metrics of an ECDM process. It was observed that no machining occurred beyond a Wg of 25 µm even when a TTR as low as 0.5 mm/min and an applied voltage greater than 44 V were used. A micro-channel with improved quality metrics was obtained using a tool travel rate (TTR) of 1 mm/min with an applied voltage of 33 V and a Wg of 2 µm while using 30% NaOH as an electrolyte. The proposed method would be helpful for researchers to fabricate precise micro-channels on glass substrates using ECDM processes
Molecular structure and vibrational spectra of 2, 4, 6 -trimethylbenzene sulphonyl chloride (FTIR & Raman) by quantum chemical calculations
No full text589-598The 2, 4, 6-trimethylbenzene sulphonyl chloride was characterized using IR and Raman spectral data. The molecular electrostatic potential surface of the 2,4,6-trimethylbenzene sulphonyl chloride (TMBS) has been visualized in electropositive potential in the region of the CH3+ group and most electronegative potential in the two oxygen atom has strong binding group. The HOMO and LUMO energies and electronic charge transfer confirms that local reactivity and global reactivity descriptors. The rate constant of 2, 4, 6-trimethylbenzene sulphonyl chloride shows strong temperature dependence. Molecular electrostatic potential (MEP) were also calculated for identification. Temperature dependence of various thermodynamic properties like (Cºp,m, Sºm and (Hºm) is increase with increase in temperature for the structure
Reprogramming of Human Multipotent Adult Progenitors into induced endodermal progenitor like cells by defined transcription Factors
No full textReprogramming of Human Multipotent Adult Progenitors into induced endodermal progenitor like cells by defined transcription Factors
Rangarajan Sambathkumar, Philip Roelandt1, Manoj kumar1, Ana Rita Mestre Rosa1, Fanos Tadessa Woldemariyam1, Sumitava Dastidar2, Qing Cai1, Eric Kalo1, Valerie Roobrouck3, Satish Khurana1, Marijke Faas5, Paul de Vos5, Catherine M Verfaillie1.
New sources of cells are needed for both therapy of diabetes (beta cells) and creation of hepatocytes (for toxicology and metabolization studies). One possibility are induced pluripotent stem cells generated from fibroblasts and then differentiated towards the lineage of interest. One drawback, definitely for clinical therapies is the possible persistence of pluripotent cells that might form teratomas. An alternative approach is to de-differentiate somatic cells to an intermediate progenitor, such as endodermal progenitors, which can then be committed to beta-cells and / or hepatocytes. We previously reported that using 16 TFs, human multipotent adult progenitor cells (MAPCs) could be transdifferentiated in cells with epithelial morphology, that could be expanded long term and expressed (mes)endodermal genes. However, more mature endodermal genes were also expressed including Albumin (ALB). We therefore tested a combination of 14 TF, which now resulted in iENDO cells; expandable cells with (mes)endodermal endogenous gene expression but without mature endodermal gene expression. Using adapted protocols for pancreatic endocrine cell differentiation and hepatocyte differentiation, we demonstrated that 14 TF iEndo cells could be committed to endocrine pancreatic endoderm, expressing PDX1, NGN3, PAX4, NKX2.2, NEUROD1, MAFA and MAFB, but not mature beta cell characteristics (no Insulin expressed). During hepatocyte differentiation, hepatoblast genes such as AFP, ALB, AAT were induced >1200 fold. Inability to create fully committed progenitors at this point may be because the differentiation conditions are not yet fully optimized. A second possibility is that the OCT4 transgene used in the preprogramming remains expressed. Currently we are testing if doxycycline inducible overexpression of OKSM combined with the other 10 TFs may support full differentiation towards beta cells and hepatocytes.sponsorship: 1 Department of Stem Cell Biology and Embryology, Stem cell Institute, KU Leuven, Herestraat 49 bus 804, 3000 Leuven2 University Medical Center Groningen(UMCG), Section Immunoendocrinology, Hanzeplein 1, EA11, 9713 GZ Groningen, The Netherlands.status: Publishe
A CRITIQUE ON CANCER VACCINE.
No full textThe goal of a successful vaccine is to prepare the immune system for invasion of a foreign pathogen and teach them to recognize antigens as well as reduce the risk of transmission. In the field of cancer, vaccines are found to be the latest discovery. Provenge? (Sipuleucel-T) is the only vaccine approved by Food and Drug Administration for the treatment of cancer. Vaccines are an appealing therapeutic strategy because they are specific. In addition they stimulate the adaptive immune system, thereby producing a memory response allowing for sustained effect without repeated therapy. Revelation of a potential anticancer treatment is as yet a test to the researchers. Thus, the development of effective cancer vaccines require, thoughtful clinical trials, and scientific progress which might induce long-term specific anticancer response and could contribute to effective and lasting elimination of malignant cells.</p
Generation of hepatocytes and pancreatic endocrine cells from human induced endodermal progenitor like cells
No full textRangarajan Sambathkumar, Philip Roelandt1, Manoj Kumar1, Ana Rita Mestre Rosa1, Fanos Tadessa Woldemariyam1, Renate Akkerman1, Sumitava Dastidar2, Qing Cai1, Eric Kalo1, Valerie Roobrouck3, Satish Khurana1, Marijke Faas5, Paul de Vos5, Catherine M Verfaillie1.
New sources of cells are needed for both therapy of diabetes (beta cells) and creation of hepatocytes (for toxicology and metabolization studies). One possibility are induced pluripotent stem cells generated from fibroblasts and then differentiated towards the lineage of interest. One drawback, definitely for clinical therapies is the possible persistence of pluripotent cells that might form teratomas. An alternative approach is to de-differentiate somatic cells to an intermediate progenitor, such as endodermal progenitors, which can then be committed to beta-cells and / or hepatocytes. We previously reported that using 16 TFs, human multipotent adult progenitor cells (MAPCs) could be transdifferentiated in cells with epithelial morphology, that could be expanded long term and expressed (mes)endodermal genes. However, more mature endodermal genes were also expressed including Albumin (ALB). We therefore tested a combination of 14 TF, which now resulted in iENDO cells; expandable cells with (mes)endodermal endogenous gene expression but without mature endodermal gene expression. Using adapted protocols for pancreatic endocrine cell differentiation and hepatocyte differentiation, we demonstrated that 14 TF iEndo cells could be committed to endocrine pancreatic endoderm, expressing PDX1, NGN3, PAX4, NKX2.2, NEUROD1, MAFA and MAFB, but not mature beta cell characteristics (no Insulin expressed). During hepatocyte differentiation, hepatoblast genes such as AFP, ALB, AAT were induced. Inability to create fully committed progenitors at this point may be because the differentiation conditions are not yet fully optimized. A second possibility is that the OCT4 transgene used in the preprogramming remains expressed. Currently we are testing if doxycycline inducible overexpression of OKSM combined with the other 10 TFs may support full differentiation towards beta cells and hepatocytes. Preliminary results suggest that upon transplantation of undifferentiated 14TFs iENDO cells under the kidney capsule of SCID mice, cells are differentiating to the hepatocyte lineage In vivo. Studies wherein iENDO cells differentiated to endocrine pancreatic cells are evaluated following grafting in vivo are pending.sponsorship: 1 Department of Stem Cell Biology and Embryology, Stem cell Institute, KU Leuven, Herestraat 49 bus 804, 3000 Leuven2 University Medical Center Groningen(UMCG), Section Immunoendocrinology, Hanzeplein 1, EA11, 9713 GZ Groningen, The Netherlands.status: Publishe
Enhancement of Fracture Toughness Characteristics of Woven Jute Fabric Mat Reinforced Epoxy Composites with SiC Fillers
No full textNatural fiber reinforced composites are attracting the attention of industries toward a sustainable and environment-friendly material for the future demands. The main drawback pertaining to the use of natural fiber composites lies in its inferior strength in comparison to its counterpart synthetic fibers. This research focuses on improving the fracture toughness of woven jute fabric mat with different orientations (0°, 30° and 45°) in epoxy resin by incorporating fillers and tested in universal tensile testing machine. Silicon carbide (SiC) particles of three sizes 26 µm, 54 µm and 72 µm were incorporated in the matrix in different weight ratios (5%, 10% and 15%). The fracture toughness of the jute/epoxy composites increases with the increase in the amount of SiC particles up to 10% addition and then it shows decreasing trend with further addition. The fracture toughness values show upward trend when the fiber orientation changed from 0° to 45°. Fractography of the tested specimen captured by scanning electron microscope which reveals the fracture of fibers and micro cracks in the epoxy matrix due to the applied load. Analysis of variance (ANOVA) is also conducted for predicting the most influencing parameters on the fracture toughness
<i>cis</i>-Bromidobis(ethylene-1,2-diamine)(methylamine)cobalt(III) dibromide
No full textIn the title compound, [CoBr(CH5N)(C2H8N2)2]Br2, the cobalt(III) ion has a distorted octahedral coordination environment and is ligated by four N atoms in the equatorial plane, with an additional N atom and a Br− ion occupying the axial positions. In the crystal, the complex cation and the two counter-anions are linked via N—H...Br and C—H...Br hydrogen bonds, forming a supramolecular framework.</jats:p
