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51.
Stanley CK Cheung Li-zhong Liu Lin-lin Lan Qiao-quan Liu Samuel SM Sun Juliana CN Chan Peter CY Tong 《BMC biotechnology》2011,11(1):37
Background
Human insulin-like growth factor-I (hIGF-I) is a growth factor which is highly resemble to insulin. It is essential for cell proliferation and has been proposed for treatment of various endocrine-associated diseases including growth hormone insensitivity syndrome and diabetes mellitus. In the present study, an efficient plant expression system was developed to produce biologically active recombinant hIGF-I (rhIGF-I) in transgenic rice grains. 相似文献52.
Hyun Yang Tae-Hee Kim Hae-Hyeog Lee Kyung-Chul Choi Yeon-pyo Hong Peter CK Leung Eui-Bae Jeung 《Reproductive biology and endocrinology : RB&E》2011,9(1):28
Human endometrium resists embryo implantation except during the 'window of receptivity'. A change in endometrial gene expression
is required for the development of receptivity. Uterine calbindin-D28k (CaBP-28k) is involved in the regulation of endometrial
receptivity by intracellular Ca2+. Currently, this protein is known to be mainly expressed in brain, kidneys, and pancreas,
but potential role(s) of CaBP-28k in the human uterus during the menstrual cycle remain to be clarified. Thus, in this study
we demonstrated the expression of CaBP-28k in the human endometrium in distinct menstrual phases. During the human menstrual
cycle, uterine expression levels of CaBP-28k mRNA and protein increased in the proliferative phase and fluctuated in these
tissues, compared with that observed in other phases. We assessed the effects of two sex-steroid hormones, 17beta-estradiol
(E2) and progesterone (P4), on the expression of CaBP-28k in Ishikawa cells. A significant increase in the expression of CaBP-28k
mRNA was observed at the concentrations of E2 (10(-9 to -7) M). In addition, spatial expression of CaBP-28k protein was detected
by immunohistochemistry. CaBP-28k was abundantly localized in the cytoplasm of the luminal and glandular epithelial cells
during the proliferative phases (early-, mid-, late-) and early-secretory phase of menstrual cycle. Taken together, these
results indicate that CaBP-28k, a uterine calcium binding protein, is abundantly expressed in the human endometrium, suggesting
that uterine expression of CaBP-28k may be involved in reproductive function during the human menstrual cycle. 相似文献
53.
54.
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55.
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
56.
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
57.
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
58.
K Nakamura M F Lazari S Li C Korgaonkar M Ascoli 《Molecular endocrinology (Baltimore, Md.)》1999,13(8):1295-1304
The extent of agonist-induced down-regulation of the LH/CG receptor (LHR) in human kidney 293 cells transfected with the rat LHR (rLHR) is much lower than in two Leydig tumor cell lines (MA-10 and R2C) that express the rodent LHR endogenously. This difference can not be attributed to differences in the recycling of internalized receptors, or in the replenishment of new receptors at the cell surface. It can be correlated, however, with the half-life of internalization of the bound agonist, which is approximately 60 min in Leydig tumor cells and about 100 min in transfected 293 cells. To determine whether the rate of internalization of the bound agonist affects down-regulation, we compared these two parameters in 293 cells expressing four rLHR mutants that enhance internalization and three mutants that impair internalization. We show that all four mutations of the rLHR that enhanced internalization enhanced down-regulation, while only one of the three mutations that impaired internalization impaired down-regulation. In addition, cotransfections of 293 cells with the rLHR-wt and three constructs that enhanced internalization (G protein-coupled receptor kinase 2, beta-arrestin, and arrestin-3) increased down-regulation, while a related construct (visual arrestin) that had no effect on internalization also had no effect on down-regulation. We conclude that the rate of internalization of the agonist-LHR complex is the main determinant of the extent of down-regulation of the LHR. 相似文献
59.
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
60.