The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Wen Guo Jiang - One of the best experts on this subject based on the ideXlab platform.
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interleukin 7 il 7 and il 7 receptor il 7r signalling complex in human solid tumours
Histology and Histopathology, 2003Co-Authors: M A A Alrawi, R E Mansel, Wen Guo JiangAbstract:Interleukin-7 (IL-7) plays an important role in the normal development and maintenance of the human immune system. Its effects are mediated via its receptor, IL-7R. Ligand-receptor engagement results in a cascade of phosphorylation events mediated by various molecules including the Janus kinases (Jak1 and Jak3), PI3-kinase, Stats (signal transducers and activators of transcription) and other molecules. The activation of IL- 7 signalling pathway results in survival, proliferation, differentiation and maturation of haematopoietic cells including B and T lymphocytes. Although the relationship of IL-7 with the development and differentiation of some haematological cancers like leukaemias and lymphomas is well recognised, little is known about it involvement with solid tumours. There are several studies that have revealed IL-7/IL-7R expression in epithelial systems and some human solid epithelial tumours. Furthermore, IL-7 can be produced by some human tumour cells and involved in tumour development and progression. In this review article we have summarised the main biological activities of IL-7 and its downstream signalling complex in relation to some human solid malignancies.
Frank Seela - One of the best experts on this subject based on the ideXlab platform.
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7-Halogenated 7-deazapurine 2′- C -methylribonucleosides
Collection of Czechoslovak Chemical Communications, 2011Co-Authors: Frank Seela, Xiaohua Peng, Simone Budow, Henning EickmeierAbstract:7-Halogenated 7-deazapurine 2′-C-methylribonucleosides related to adenosine, inosine and guanosine were synthesized employing a “one-pot” glycosylation protocol (Vorbruggen glycosylation). The immunosine 2′-C-methylribonucleoside 4 was prepared by the same glycosylation strategy. By this route, the synthesis of the anti-HCV active compound 7-fluoro-7-deaza-2′-C-methyladenosine (1b) was notably simplified, while other nucleosides were synthesized for the first time. A single-crystal X-ray analysis of 7-fluoro-7-deaza-2′-C-methylinosine (2b) was performed showing that the glycosylic bond adopts an anti orientation (χ = –139.9(2)°), while the sugar moiety has an N conformation (C3′-endo; P = 4.3(1)°, τm = 42.4(1)°).
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Pyrrolo[2,3- d ]pyrimidine β-L-Nucleosides Containing 7-Deazaadenine, 2-Amino-7-deazaadenine, 7-Deazaguanine, 7-Deazaisoguanine, and 7-Deazaxanthine
Collection of Czechoslovak Chemical Communications, 2006Co-Authors: Frank Seela, Xiaohua PengAbstract:The synthesis and properties of 7-deazapurine β-L-nucleosides are described. The stereoselective glycosylation of the anions of 2-amino-6-chloro-7-deazapurines 9a, 9b or 6-chloro-7-deazapurines 13a, 13d with 3,5-di-O-(4-methylbenzoyl)-2-deoxy-α-L-erythro-pentofuranosyl chloride (8) furnished the β-L-2'-deoxyribonucleosides 1-4. The synthesis of β-L-ribonucleosides 5-7 used the Silyl-Hilbert-Johnson reaction (TMSOTf/BSA/MeCN) performed under Vorbruggen conditions for the glycosylation of 7-halogenated 6-chloro-2-pivalamido-7-deazapurines 17b-17d with 1-O-acetyl-2,3,5-tri-O-benzoyl-L-ribofuranose (16). Single-crystal X-ray analyses were performed and CD spectra were measured to assign the configuration. The antiviral activity against selected DNA and RNA viruses is reported.
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7-deazapurin-2,6-diamine and 7-deazaguanine: synthesis and property of 7-substituted nucleosides and oligonucleotides.
Nucleosides nucleotides & nucleic acids, 2005Co-Authors: Frank Seela, Xiaohua Peng, Xin MingAbstract:The synthesis of 7-substituted 7-deazaguanine and 7-deazaadenine ribonucleosides 1–2, the incorporation of 3a–d into oligonucleotides, and the stability of the corresponding duplexes and base discrimination are described. The pKa values of 3–4 are determined.
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regioselective syntheses of 7 halogenated 7 deazapurine nucleosides related to 2 amino 7 deaza 2 deoxyadenosine and 7 deaza 2 deoxyisoguanosine
Synthesis, 2004Co-Authors: Frank Seela, Xiaohua PengAbstract:The syntheses of 7-halogenated derivatives 3b-e of 2-amino-7-deaza-2'-deoxyadenosine as well as 7-bromo and 7-chloro-7-deaza-2'-deoxyisoguanosines 4b-c are described. Nucleobase anion glycosylation was employed for the convergent nucleoside synthesis. The regioselective 7-halogenation was performed either on the nucleoside precursor 7 or on the nucleobase 12. Two bromo substituents were introduced in the 7- and 8-position when the unprotected 2-amino nucleoside 9 was used. Conformational analysis of the sugar moiety of nucleosides 3a-e and 4a-c was performed on the basis of vicinal 1 H, 1 H NMR coupling constants.
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7-HALOGENATED 7-DEAZA-2'-DEOXYINOSINES
Helvetica Chimica Acta, 1999Co-Authors: Natalya Ramzaeva, Cathrin Mittelbach, Frank SeelaAbstract:The synthesis of the 7-deaza-2′-deoxyinosine derivatives 3a – c with chloro, bromo, and iodo substituents at position 7 is described. Glycosylation of the 7-halogenated 6-chloro-7-deazapurines 4a – c or of the 7-halogenated 6-chloro-7-deaza-2-(methylthio)purines 9a – c with 2-deoxy-3,5-di-O-(4-toluoyl)-α-D-erythro-pentofuranosyl chloride (5) furnished the intermediates 7a – c and 11a – c, respectively, which gave, upon deprotection, the desired nucleosides 3a – c.
M J Maeurer - One of the best experts on this subject based on the ideXlab platform.
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Interleukin-7 (IL-7) and IL-7 splice variants affect differentiation of human neural progenitor cells
Genes & Immunity, 2010Co-Authors: M Moors, N K Vudattu, J Abel, U Krämer, L Rane, N Ulfig, S Ceccatelli, V Seyfert-margolies, E Fritsche, M J MaeurerAbstract:Alternative splicing of pre-mRNA increases proteomic diversity, a crucial mechanism in defining tissue identity. We demonstrate differentially spliced interleukin (IL)-7 in distinct anatomic areas in the adult, in developing human brains and in normal human neuronal progenitor (NHNP) cells. IL-7c (c, the canonical form spanning all six exons) or its variants IL-7δ5, δ4 or δ4/5 were cloned and expressed as recombinant proteins. IL-7 and splice variants were able to shift the differentiation of NHNP cells as compared with the diluent control ( P δ4/5>IL-7δ5); IL-7δ4 exhibited a significantly weaker potency. Differentiation was confirmed by transcriptome analysis of IL-7c-stimulated neural NHNP cells, resulting in 58 differentially expressed genes; some of these are involved in neural differentiation, for example, the developmentally regulated transcription factor krüppel-like factor 12, musashi 2, a translational regulator of cell fate or the sonic hedgehog receptor patch 1. This suggests that IL-7 influences neural development at a molecular level by participating in human brain architecture through glia cell formation: a paradigm that alternative splicing in cytokines, for example, for IL-7, has a physiological role in human organ development and progenitor cell differentiation.
Tai-c. Chiang - One of the best experts on this subject based on the ideXlab platform.
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C60 encapsulation of the Si(111)‐(7×7) surface
Applied Physics Letters, 1992Co-Authors: Hawoong Hong, W. E. Mcmahon, Paul Zschack, Deng-sung Lin, R. D. Aburano, Haydn Chen, Tai-c. ChiangAbstract:The structure of a Si(111)‐(7×7) surface capped by a 200 A film of C60 was studied by grazing‐incidence x‐ray diffraction. The Si(111)‐(7×7) reconstruction prepared in vacuum, including the loosely bonded ‘‘adatoms’’ on the surface, is preserved under the C60 overlayer. This result illustrates that C60 can be used as an inert cap for surfaces and suggests potentially interesting applications in surface science research and electronic device engineering.
Xiaohua Peng - One of the best experts on this subject based on the ideXlab platform.
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7-Halogenated 7-deazapurine 2′- C -methylribonucleosides
Collection of Czechoslovak Chemical Communications, 2011Co-Authors: Frank Seela, Xiaohua Peng, Simone Budow, Henning EickmeierAbstract:7-Halogenated 7-deazapurine 2′-C-methylribonucleosides related to adenosine, inosine and guanosine were synthesized employing a “one-pot” glycosylation protocol (Vorbruggen glycosylation). The immunosine 2′-C-methylribonucleoside 4 was prepared by the same glycosylation strategy. By this route, the synthesis of the anti-HCV active compound 7-fluoro-7-deaza-2′-C-methyladenosine (1b) was notably simplified, while other nucleosides were synthesized for the first time. A single-crystal X-ray analysis of 7-fluoro-7-deaza-2′-C-methylinosine (2b) was performed showing that the glycosylic bond adopts an anti orientation (χ = –139.9(2)°), while the sugar moiety has an N conformation (C3′-endo; P = 4.3(1)°, τm = 42.4(1)°).
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Pyrrolo[2,3- d ]pyrimidine β-L-Nucleosides Containing 7-Deazaadenine, 2-Amino-7-deazaadenine, 7-Deazaguanine, 7-Deazaisoguanine, and 7-Deazaxanthine
Collection of Czechoslovak Chemical Communications, 2006Co-Authors: Frank Seela, Xiaohua PengAbstract:The synthesis and properties of 7-deazapurine β-L-nucleosides are described. The stereoselective glycosylation of the anions of 2-amino-6-chloro-7-deazapurines 9a, 9b or 6-chloro-7-deazapurines 13a, 13d with 3,5-di-O-(4-methylbenzoyl)-2-deoxy-α-L-erythro-pentofuranosyl chloride (8) furnished the β-L-2'-deoxyribonucleosides 1-4. The synthesis of β-L-ribonucleosides 5-7 used the Silyl-Hilbert-Johnson reaction (TMSOTf/BSA/MeCN) performed under Vorbruggen conditions for the glycosylation of 7-halogenated 6-chloro-2-pivalamido-7-deazapurines 17b-17d with 1-O-acetyl-2,3,5-tri-O-benzoyl-L-ribofuranose (16). Single-crystal X-ray analyses were performed and CD spectra were measured to assign the configuration. The antiviral activity against selected DNA and RNA viruses is reported.
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7-deazapurin-2,6-diamine and 7-deazaguanine: synthesis and property of 7-substituted nucleosides and oligonucleotides.
Nucleosides nucleotides & nucleic acids, 2005Co-Authors: Frank Seela, Xiaohua Peng, Xin MingAbstract:The synthesis of 7-substituted 7-deazaguanine and 7-deazaadenine ribonucleosides 1–2, the incorporation of 3a–d into oligonucleotides, and the stability of the corresponding duplexes and base discrimination are described. The pKa values of 3–4 are determined.
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regioselective syntheses of 7 halogenated 7 deazapurine nucleosides related to 2 amino 7 deaza 2 deoxyadenosine and 7 deaza 2 deoxyisoguanosine
Synthesis, 2004Co-Authors: Frank Seela, Xiaohua PengAbstract:The syntheses of 7-halogenated derivatives 3b-e of 2-amino-7-deaza-2'-deoxyadenosine as well as 7-bromo and 7-chloro-7-deaza-2'-deoxyisoguanosines 4b-c are described. Nucleobase anion glycosylation was employed for the convergent nucleoside synthesis. The regioselective 7-halogenation was performed either on the nucleoside precursor 7 or on the nucleobase 12. Two bromo substituents were introduced in the 7- and 8-position when the unprotected 2-amino nucleoside 9 was used. Conformational analysis of the sugar moiety of nucleosides 3a-e and 4a-c was performed on the basis of vicinal 1 H, 1 H NMR coupling constants.