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21.
22.
Zusammenfassung Der Mechanismus der Serini-Reaktion wird kurz erörtert und ein 17, 20-Oxyd als Zwischenprodukt vorgeschlagen. Das stereochemische Ergebnis der Reaktion soll von zwei Faktoren abhängig sein, und zwar: 1. von der Geometrie des « transition state » und 2. von der Konfiguration des Oxydrings. Ausgehend von diesen Überlegungen, kann vorausgesagt werden, daßReichsteins Substanz 0-Diacetat durch die Serini-Reaktion in ein 17-Iso-20-keton und nicht in ein 17-Normal-20-keton umgewandelt werden soll. Tatsächlich ist das 17-Isoallopregnanol-(3)-on-20 als einziges Produkt experimentell aufgefunden worden. 相似文献
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24.
St Onge RP Mani R Oh J Proctor M Fung E Davis RW Nislow C Roth FP Giaever G 《Nature genetics》2007,39(2):199-206
Systematic genetic interaction studies have illuminated many cellular processes. Here we quantitatively examine genetic interactions among 26 Saccharomyces cerevisiae genes conferring resistance to the DNA-damaging agent methyl methanesulfonate (MMS), as determined by chemogenomic fitness profiling of pooled deletion strains. We constructed 650 double-deletion strains, corresponding to all pairings of these 26 deletions. The fitness of single- and double-deletion strains were measured in the presence and absence of MMS. Genetic interactions were defined by combining principles from both statistical and classical genetics. The resulting network predicts that the Mph1 helicase has a role in resolving homologous recombination-derived DNA intermediates that is similar to (but distinct from) that of the Sgs1 helicase. Our results emphasize the utility of small molecules and multifactorial deletion mutants in uncovering functional relationships and pathway order. 相似文献
25.
A genome-wide association study for celiac disease identifies risk variants in the region harboring IL2 and IL21 总被引:14,自引:0,他引:14
van Heel DA Franke L Hunt KA Gwilliam R Zhernakova A Inouye M Wapenaar MC Barnardo MC Bethel G Holmes GK Feighery C Jewell D Kelleher D Kumar P Travis S Walters JR Sanders DS Howdle P Swift J Playford RJ McLaren WM Mearin ML Mulder CJ McManus R McGinnis R Cardon LR Deloukas P Wijmenga C 《Nature genetics》2007,39(7):827-829
We tested 310,605 SNPs for association in 778 individuals with celiac disease and 1,422 controls. Outside the HLA region, the most significant finding (rs13119723; P = 2.0 x 10(-7)) was in the KIAA1109-TENR-IL2-IL21 linkage disequilibrium block. We independently confirmed association in two further collections (strongest association at rs6822844, 24 kb 5' of IL21; meta-analysis P = 1.3 x 10(-14), odds ratio = 0.63), suggesting that genetic variation in this region predisposes to celiac disease. 相似文献
26.
Lindahl E Nyman U Melles E Sigmundsson K Ståhlberg M Wahren J Obrink B Shafqat J Joseph B Jörnvall H 《Cellular and molecular life sciences : CMLS》2007,64(4):479-486
Proinsulin C-peptide is known to bind specifically to cell membranes and to exert intracellular effects, but whether it is
internalized in target cells is unknown. In this study, using confocal microscopy and immunostained or rhodamine-labeled peptide,
we show that C-peptide is internalized and localized to the cytosol of Swiss 3T3 and HEK-293 cells. In addition, transport
into nuclei was found using the labeled peptide. The internalization was followed at 37°C for up to 1 h, and was reduced at
4°C and after preincubation with pertussis toxin. Hence, it is concluded to occur via an energy-dependent, pertussis toxin-sensitive
mechanism and without detectable degradation within the experimental time course. Surface plasmon resonance measurements demonstrated
binding of HEK-293 cell extract components to C-peptide, and subsequent elution of bound material revealed the components
to be intracellular proteins. The identification of C-peptide cellular internalization, intracellular binding proteins, absence
of rapid subsequent C-peptide degradation and apparent nuclear internalization support a maintained activity similar to that
of an intracrine peptide hormone. Hence, the data suggest the possibility of one further C-peptide site of action.
Received 31 October 2006; received after revision 27 December 2006; accepted 30 December 2006 相似文献
27.
Strell C Lang K Niggemann B Zaenker KS Entschladen F 《Cellular and molecular life sciences : CMLS》2007,64(24):3306-3316
The extravasation of leukocytes and tumor cells is a multi-step process with the involvement of various adhesion molecules
depending on the three steps rolling, adhesion, and diapedesis. We have developed an in vitro model, by which we investigated the rolling and adhesion of neutrophil granulocytes and MDA-MB-468 human breast carcinoma
cells to lung endothelial cells under physiological flow-conditions. We found that norepinephrine had an inhibitory function
on the fMLP-promoted adhesion of neutrophil granulocytes due to a down-regulation of β2-integrin. Furthermore, neutrophil
granulocytes serve as linking cells for the interaction of the MDA-MB-468 cells with the endothelium, which are both β2-integrin
negative, but express the β2-integrin ligand ICAM-1. In addition, we show here that N-cadherin is up-regulated on the endothelial
cells and on neutrophil granulocytes in response to fMLP. This up-regulation resulted in a significant increase of adherent
MDA-MB-468 cells, which are also N-cadherin positive.
Received 3 September 2007; received after revision 17 October 2007; accepted 22 October 2007 相似文献
28.
KERMACK WO 《Science progress》1948,36(142):288-292
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