排序方式: 共有589条查询结果,搜索用时 281 毫秒
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Van Laethem A Nys K Van Kelst S Claerhout S Ichijo H Vandenheede JR Garmyn M Agostinis P 《Free radical biology & medicine》2006,41(9):1361-1371
The p38 MAPK pathway controls critical premitochondrial events culminating in apoptosis of UVB-irradiated human keratinocytes, but the upstream mediators of this stress signal are not completely defined. This study shows that in human keratinocytes exposed to UVB the generation of reactive oxygen species (ROS) acts as a mediator of apoptosis signal regulating kinase-1 (Ask-1), a redox-sensitive mitogen-activated protein kinase kinase kinase (MAP3K) regulating p38 MAPK and JNK cascades. The NADPH oxidase antagonist diphenylene iodonium chloride and the EGFR inhibitor AG1487 prevent UVB-mediated ROS generation, the activation of the Ask-1-p38 MAPK stress response pathway, and apoptosis, evidencing the link existing between the early plasma membrane-generated ROS and the activation of a lethal cascade initiated by Ask-1. Consistent with this, Ask-1 overexpression considerably sensitizes keratinocytes to UVB-induced mitochondrial apoptosis. Although the JNK pathway is also stimulated after UVB, the killing effect of Ask-1 overexpression is reverted by p38 MAPK inhibition, suggesting that Ask-1 exerts its lethal effects mainly through the p38 MAPK pathway. Moreover, p38alpha(-/-) murine embryonic fibroblasts are protected from UVB-induced apoptosis even if JNK activation is fully preserved. These results argue for an important role of the UVB-generated ROS as mediators of the Ask-1-p38 MAPK pathway that, by culminating in apoptosis, restrains the propagation of potentially mutagenic keratinocytes. 相似文献
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Independent differentiation of mammotropes and somatotropes in the chicken embryonic pituitary gland
Zheng J Nakamura K Maseki Y Geelissen SM Berghman LR Sakai T 《Histochemistry and cell biology》2006,125(4):429-439
It has been reported that mammotropes in a rodent pituitary gland are derived from somatotropes via somatomammotropes (SMTs),
cells that produce both growth hormone (GH) and prolactin (Prl). However, no studies have been done on the transdifferentiation
of somatotropes in the chicken pituitary gland. In this study, in order to determine the origin of mammotropes, we studied
detail property of appearance of chicken somatotropes, mammotropes and pit-1 cells and then evaluated the existence of SMTs
in the chicken embryonic pituitary gland. Immunohistochemical analysis revealed that GH-immunopositive (GH-ip) cells appeared
on embryonic day (E) 14 and were mainly distributed in the caudal lobe, while Prl-immunopositive (Prl-ip) cells appeared in
the cephalic lobe of the pituitary gland on E16. In situ hybridization (ISH) and RT-PCR analysis showed that expression of
GH and Prl mRNA starts at E12 in the caudal lobe and at E14 in the cephalic lobe respectively. Pit-1 mRNA was first detected
on E5 by RT-PCR, and pit-1 mRNA-expressing cells were found in the cephalic lobe on E8. Then with the ontogeny of the chicken,
these cells spread into both lobes. Using a double staining method with ISH and immunohistochemistry, we could not detect
the existence of SMTs in the chicken embryonic pituitary gland even in the marginal region of either lobe. These results suggest
that chicken somatotropes and mammotropes independently appear in different lobes of pituitary gland and that transdifferentiation
from somatotropes to mammotropes is not the central route for differentiation of mammotropes in the embryonic chicken pituitary
gland. 相似文献
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Termont S Vandenbroucke K Iserentant D Neirynck S Steidler L Remaut E Rottiers P 《Applied and environmental microbiology》2006,72(12):7694-7700
Interleukin-10 (IL-10) is a promising candidate for the treatment of inflammatory bowel disease. Intragastric administration of Lactococcus lactis genetically modified to secrete IL-10 in situ in the intestine was shown to be effective in healing and preventing chronic colitis in mice. However, its use in humans is hindered by the sensitivity of L. lactis to freeze-drying and its poor survival in the gastrointestinal tract. We expressed the trehalose synthesizing genes from Escherichia coli under control of the nisin-inducible promoter in L. lactis. Induced cells accumulated intracellular trehalose and retained nearly 100% viability after freeze-drying, together with a markedly prolonged shelf life. Remarkably, cells producing trehalose were resistant to bile, and their viability in human gastric juice was enhanced. None of these effects were seen with exogenously added trehalose. Trehalose accumulation did not interfere with IL-10 secretion or with therapeutic efficacy in murine colitis. The newly acquired properties should enable a larger proportion of the administered bacteria to reach the gastrointestinal tract in a bioactive form, providing a means for more effective mucosal delivery of therapeutics. 相似文献
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Martine Geraerts Sofie Willems Veerle Baekelandt Zeger Debyser Rik Gijsbers 《BMC biotechnology》2006,6(1):34
Background
Lentiviral vectors are efficient vehicles for stable gene transfer in dividing and non-dividing cells. Several improvements in vector design to increase biosafety and transgene expression, have led to the approval of these vectors for use in clinical studies. Methods are required to analyze the quality of lentiviral vector production, the efficiency of gene transfer and the extent of therapeutic gene expression. 相似文献69.
Ilse C. Van Opzeeland Sofie M. Van Parijs Stephan Frickenhaus Cornelia M. Kreiss Olaf Boebel 《Marine Mammal Science》2012,28(2):E158-E172
Individually stereotyped vocalizations often play an important role in relocation of offspring in gregarious breeders. In phocids, mothers often alternate between foraging at sea and attending their pup. Pup calls are individually distinctive in various phocid species. However, experimental evidence for maternal recognition is rare. In this study, we recorded Weddell seal (Leptonychotes weddellii) pup vocalizations at two whelping patches in Atka Bay, Antarctica, and explored individual vocal variation based on eight vocal parameters. Overall, 58% of calls were correctly classified according to individual. For males (n= 12) and females (n= 9), respectively, nine and seven individuals were correctly identified based on vocal parameters. To investigate whether mothers respond differently to calls of familiar vs. unfamiliar pups, we conducted playback experiments with 21 mothers. Maternal responses did not differ between playbacks of own, familiar, and unfamiliar pup calls. We suggest that Weddell seal pup calls may need to contain only a critical amount of individually distinct information because mothers and pups use a combination of sensory modalities for identification. However, it cannot be excluded that pup developmental factors and differing environmental factors between colonies affect pup acoustic behavior and the role of acoustic cues in the relocation process. 相似文献
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Remans T Thijs S Truyens S Weyens N Schellingen K Keunen E Gielen H Cuypers A Vangronsveld J 《Annals of botany》2012,110(2):239-252