We reanalyse the time-variable light curves of the transiting planetary system PTFO 8-8695, in which a planet of 3 to 4 Jupiter masses orbits a rapidly rotating pre-main-sequence star. Both the ...planetary orbital period P
orb of 0.448 d and the stellar spin period P
s of less than 0.671 d are unusually short, which makes PTFO 8-8695 an ideal system to check the model of gravity darkening and nodal precession. While the previous analysis of PTFO 8-8695 assumed that the stellar spin and planetary orbital periods are the same, we extend the analysis by discarding the spin–orbit synchronous condition, and find three different classes of solutions roughly corresponding to the nodal precession periods of 199 ± 16, 475 ± 21, and 827 ± 53 d that reproduce the transit light curves observed in 2009 and 2010. We compare the predicted light curves of the three solutions against the photometry data of a few percent accuracy obtained at Koyama Astronomical Observatory in 2014 and 2015, and find that the solution with a precession period of 199 ± 16 d is preferred even though it is preliminary. Future prospects and implications for other transiting systems are briefly discussed.
We reanalyse the time-variable lightcurves of the transiting planetary system PTFO 8-8695, in which a planet of 3 to 4 Jupiter mass orbits around a rapidly rotating pre-main-sequence star. Both the ...planetary orbital period of 0.448 days and the stellar spin period less than 0.671 days are unusually short, which makes PTFO 8-8695 an ideal system to check the model of gravity darkening and nodal precession. While the previous analysis of PTFO 8-8695 assumed that the stellar spin and planetary orbital periods are the same, we extend the analysis by discarding the spin-orbit synchronous condition, and find three different classes of solutions roughly corresponding to the nodal precession periods of 199\(\pm\)16, 475\(\pm\)21, and 827\(\pm\)53 days that reproduce the transit lightcurves observed in 2009 and 2010. We compare the predicted lightcurves of the three solutions against the photometry data of a few percent accuracy obtained at Koyama Astronomical Observatory in 2014 and 2015, and find that the solution with the precession period of 199\(\pm\)16 days is preferred even though preliminary. Future prospect and implications to other transiting systems are briefly discussed.
The possible role of leptin in colorectal tumors has been investigated in previous studies; however, to date, the conclusions remain under debate. Therefore, we investigated the serum leptin levels ...in colorectal adenoma patients. In addition, expression of the leptin receptor, and the leptin receptor‐mediated signaling pathways were investigated in biopsy specimens collected from human patients with colorectal adenoma. No significant difference in the mean serum leptin level was observed between the colorectal adenoma patients and the control subjects; however, increased expression and activation of the leptin receptor, as indicated by findings such as the phosphorylation of Tyr 1141, was observed in the colorectal adenoma tissues. In addition, activation of the JAK/STAT signaling pathway mediated by the leptin receptor and increased transcriptional regulation of downstream target molecules were observed in colorectal adenomas compared with the non‐adenoma tissues. These results indicate STAT3‐mediated leptin receptor signaling pathways may be activated in human colorectal adenomas. (Cancer Sci 2011; 102: 367–372)
Although a number of recent studies have reported the involvement of leptin in colorectal carcinogenesis, findings are contradictory and difficult to interpret. Our group has previously reported that ...leptin signaling might have an important role in the development of colorectal adenomas. In this study, we investigated leptin signaling in colorectal carcino-genesis focusing in particular on the differences in leptin signaling between colorectal adenoma and cancer. Whereas no significant differences in the serum leptin levels were observed among normal control subjects and adenoma/cancer patients, increased expression and activation of the long form leptin receptor (ObRL) was observed in colorectal adenoma and cancer tissues compared with the normal colorectal tissues. However, no significant differences were observed between the colorectal adenoma and cancer tissues. Significant increases in the phosphorylation levels of important molecules of the JAK/STAT signaling pathway, located downstream of leptin signaling, and transcriptional regulation of STAT3-downstream target molecules were observed in colorectal adenoma tissue compared with the findings in normal colorectal tissues. Furthermore, these changes were significantly more pronounced in colorectal cancer compared to colorectal adenoma tissues. This is the first analysis of leptin and JAK/STAT signaling in a human colorectal adenoma-carcinoma sequence. These results suggest that the STAT3-mediated leptin signaling through the activation of ObRL may be involved in colorectal carcinogenesis, both in adenoma formation and in the progression to cancer. STAT3 signaling in colorectal cancer may be mediated not only by leptin but by other factors.
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