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排序方式: 共有67条查询结果,搜索用时 15 毫秒
41.
Dong Wook Park Kyung-Chul Choi Colin D MacCalman Peter CK Leung 《Reproductive biology and endocrinology : RB&E》2009,7(1):81
Endometrial carcinoma is the most common neoplasm of the female genital tract, accounting for nearly one half of all gynecologic
cancers in the Western world. Although intensive research on pathological phenomena of endometrial cancer is currently going
on, but exact cause and biological aspects of this disease are not well described yet. In addition to well-documented roles
of gonadotropin-releasing hormone (GnRH) in hypopituitary ovarian (HPO) axis, the agonistic or antagonistic analogs (or both)
of GnRH have been shown to inhibit the proliferation of a variety of human gynecologic cancers. Thus, in the present study,
we further examined the possibility that GnRH induces integrin beta3 and activation of focal adhesion kinase (FAK) through
mitogen-activated protein kinases (MAPKs), ERK1/2 and p38, to inhibit the growth of HEC1A endometrial cancer cell line. As
a result, both GnRH-I and GnRH-II resulted in a significant increase in integrin beta3 expression and evoked the activation
of FAK in a time-dependent manner in these cells. In addition, these analogs induced an activation of ERK1/2 and p38 MAPK
in a time-dependent manner as downstream pathways of FAK. It appears that GnRH-II has much greater effect on the activation
of FAK, ERK1/2 and p38 compared to GnRH-I in these cells. Further, we demonstrated that the growth inhibition of HEC1A cells
by GnRH-I or GnRH-II is involved in the activation of integrin-FAK and ERK1/2 and p38 MAPK pathways. Taken together, these
results suggest that GnRH may be involved in the inhibition of endometrial cancer cell growth via activation of integrin beta3
and FAK as a direct effect. This knowledge could contribute to a better understanding of the mechanisms implicated in the
therapeutic action of GnRH and its biomedical application for the treatment against endometrial cancer. 相似文献
42.
Li Tang Yu Zhang Hong Pan Qiong Luo Xiao-Ming Zhu Min-Yue Dong Peter CK Leung Jian-Zhong Sheng He-Feng Huang 《Reproductive biology and endocrinology : RB&E》2009,7(1):144-8
Background
Progesterone plays an important role in the proliferation and differentiation of human endometrial cells (hECs). Large-dose treatment with progesterone has been used for treatment of endometrial proliferative disorders. However, the mechanisms behind remain unknown. 相似文献43.
Background
A large number of genes usually show differential expressions in a microarray experiment with two types of tissues, and the p-values of a proper statistical test are often used to quantify the significance of these differences. The genes with small p-values are then picked as the genes responsible for the differences in the tissue RNA expressions. One key question is what should be the threshold to consider the p-values small. There is always a trade off between this threshold and the rate of false claims. Recent statistical literature shows that the false discovery rate (FDR) criterion is a powerful and reasonable criterion to pick those genes with differential expression. Moreover, the power of detection can be increased by knowing the number of non-differential expression genes. While this number is unknown in practice, there are methods to estimate it from data. The purpose of this paper is to present a new method of estimating this number and use it for the FDR procedure construction. 相似文献44.
Jian Guo Andrew V Schally Marta Zarandi Jozsef Varga Peter CK Leung 《Reproductive biology and endocrinology : RB&E》2010,8(1):54
Background
Antagonists of growth hormone-releasing hormone (GHRH) are being developed for the treatment of various human cancers. 相似文献45.
Victor?TS?Chen Chun?Peng Peter?CK?LeungEmail author 《Reproductive biology and endocrinology : RB&E》2003,1(1):29
Activin is known to play an important regulatory role in reproduction, including pregnancy. To further examine the role and signaling mechanism of activin in regulating placental function, the steady-state level of activin type I receptor (ActRI) mRNA in immortalized extravillous trophoblasts (IEVT) cells was measured using competitive PCR (cPCR). An internal standard of ActRI cDNA for cPCR was constructed for the quantification of ActRI mRNA levels in IEVT cells. ActRI mRNA levels were increased in a dose-dependent manner by activin-A with the maximal effect observed at the dose of 10 ng/ml. Time course studies revealed that activin-A had maximal effects on ActRI mRNA levels at 6 hours after treatment. The effects of activin-A on ActRI mRNA levels was blocked by follistatin, an activin binding protein, in a dose-dependent manner. In addition, inhibin-A inhibited basal, as well as activin-A-induced ActRI mRNA levels. These findings provide evidence, for the first time, that activin-A modulates ActRI mRNA levels in human trophoblast cells. 相似文献
46.
A flavonoid mutant of barley (Hordeum vulgare L.) exhibits increased sensitivity to UV-B radiation in the primary leaf 总被引:4,自引:2,他引:2
The aim of the present investigation was to define the role of soluble flavonoids as UV-B protectants in the primary leaf of barley (Hordeum vulgare L.). For this purpose we used a mutant line (Ant 287) from the Carlsberg collection of proanthocyanidin-free barley containing only 7% of total extractable flavonoids in the primary leaf as compared to the mother variety (Hiege 550/75). Seven-day-old leaves from plants grown under high visible light with or without supplementary UV-B radiation were used for the determination of UV-B sensitivity. UV-B-induced changes were assessed from parameters of chlorophyll fluorescence of photosystem II, including initial and maximum fluorescence, apparent quantum yield, and photochemical and non-photochemical quenching. A quartz fibre-optic microprobe was used to evaluate the amount of potentially harmful UV-B (310 nm radiation) penetrating into the leaf as a direct consequence of flavonoid deficiency. Our data indicate an essential role of flavonoids in UV-B protection of barley primary leaves. In leaves of the mutant line grown under supplementary UV-B, an increase in 310nm radiation in the mesophyll and a strong decrease in the quantum yield of photosynthesis were observed as compared to the corresponding mother variety. Primary leaves of liege responded to supplementary UV-B radiation with a 30% increase in the major flavonoid saponarin and a 500% increase in the minor compound lutonarin. This is assumed to be an efficient protective response since no changes in variable chlorophyll fluorescence were apparent. In addition, a further reduction in UV-B penetration into the mesophyll was recorded in these leaves. 相似文献
47.
Effects of elevated ozone on CO2 uptake and leaf structure in sugar maple under two light environments 总被引:2,自引:2,他引:0
The interactive effects of ozone and light on leaf structure, carbon dioxide uptake and short-term carbon allocation of sugar maple ( Acer saccharum Marsh.) seedlings were examined using gas exchange measurements and 14 C-macroautoradiographic techniques. Two-year-old sugar maple seedlings were fumigated from budbreak for 5 months with ambient or 3 × ambient ozone in open-top chambers, receiving either 35% (high light) or 15% (low light) of full sunlight. Ozone accelerated leaf senescence, and reduced net photosynthesis, 14 CO2 uptake and stomatal conductance, with the effects being most pronounced under low light. The proportion of intercellular space increased in leaves of seedlings grown under elevated ozone and low light, possibly enhancing the susceptibility of mesophyll cells to ozone by increasing the cumulative dose per mesophyll cell. Indeed, damage to spongy mesophyll cells in the elevated ozone × low light treatment was especially frequent. 14 C macroautoradioraphy revealed heterogeneous uptake of 14 CO2 in well defined areole regions, suggesting patchy stomatal behaviour in all treatments. However, in seedlings grown under elevated ozone and low light, the highest 14 CO2 uptake occurred along larger veins, while interveinal regions exhibited little or no uptake. Although visible symptoms of ozone injury were not apparent in these seedlings, the cellular damage, reduced photosynthetic rates and reduced whole-leaf chlorophyll levels corroborate the visual scaling of whole-plant senescence, suggesting that the ozone × low light treatment accelerated senescence or senescence-like injury in sugar maple. 相似文献
48.
The expected upward shift of trees due to climate warming is supposed to be a major threat to range‐restricted high‐altitude species by shrinking the area of their suitable habitats. Our projections show that areas of endemism of five taxonomic groups (vascular plants, snails, spiders, butterflies, and beetles) in the Austrian Alps will, on average, experience a 77% habitat loss even under the weakest climate change scenario (+1.8 °C by 2100). The amount of habitat loss is positively related with the pooled endemic species richness (species from all five taxonomic groups) and with the richness of endemic vascular plants, snails, and beetles. Owing to limited postglacial migration, hotspots of high‐altitude endemics are situated in rather low peripheral mountain chains of the Alps, which have not been glaciated during the Pleistocene. There, tree line expansion disproportionally reduces habitats of high‐altitude species. Such legacies of climate history, which may aggravate extinction risks under future climate change have to be expected for many temperate mountain ranges. 相似文献
49.
50.
ROBIN ENGLER CHRISTOPHE F. RANDIN WILFRIED THUILLER STEFAN DULLINGER NIKLAUS E. ZIMMERMANN MIGUEL B. ARAÚJO PETER B. PEARMAN GWENAËLLE LE LAY CHRISTIAN PIEDALLU CÉCILE H. ALBERT PHILIPPE CHOLER GHEORGHE COLDEA XAVIER
De LAMO THOMAS DIRNBÖCK JEAN‐CLAUDE GÉGOUT DANIEL GÓMEZ‐GARCÍA JOHN‐ARVID GRYTNES EINAR HEEGAARD FRIDE HØISTAD DAVID NOGUÉS‐BRAVO SIGNE NORMAND MIHAI PUŞCAŞ MARIA‐TERESA SEBASTIÀ ANGELA STANISCI JEAN‐PAUL THEURILLAT MANDAR R. TRIVEDI PASCAL VITTOZ ANTOINE GUISAN 《Global Change Biology》2011,17(7):2330-2341
Continental‐scale assessments of 21st century global impacts of climate change on biodiversity have forecasted range contractions for many species. These coarse resolution studies are, however, of limited relevance for projecting risks to biodiversity in mountain systems, where pronounced microclimatic variation could allow species to persist locally, and are ill‐suited for assessment of species‐specific threat in particular regions. Here, we assess the impacts of climate change on 2632 plant species across all major European mountain ranges, using high‐resolution (ca. 100 m) species samples and data expressing four future climate scenarios. Projected habitat loss is greater for species distributed at higher elevations; depending on the climate scenario, we find 36–55% of alpine species, 31–51% of subalpine species and 19–46% of montane species lose more than 80% of their suitable habitat by 2070–2100. While our high‐resolution analyses consistently indicate marked levels of threat to cold‐adapted mountain florae across Europe, they also reveal unequal distribution of this threat across the various mountain ranges. Impacts on florae from regions projected to undergo increased warming accompanied by decreased precipitation, such as the Pyrenees and the Eastern Austrian Alps, will likely be greater than on florae in regions where the increase in temperature is less pronounced and rainfall increases concomitantly, such as in the Norwegian Scandes and the Scottish Highlands. This suggests that change in precipitation, not only warming, plays an important role in determining the potential impacts of climate change on vegetation. 相似文献