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121.
122.
Masayoshi Ono John W. Perry Takami Oka 《In vitro cellular & developmental biology. Plant》1981,17(2):121-128
Summary Cortisol was previously shown to elicit a concentration-dependent inhibition of α-lactalbumin accumulation in midpregnant
mouse mammary gland cultured in medium containing optimal concentrations of 5 μg/ml prolactin and insulin. In contrast, casein
accumulation under these conditions was progressively stimulated by addition of increasing amounts of cortisol (Ono, M.; Oka,
T. Cell 19: 473–480; 1980). In the present study we found that in the presence of a suboptimal concentration of 0.5 μg/ml
prolactin, 2.8×10−9
M to 2.8×10−7
M cortisol stimulated α-lactalbumin accumulation. Furthermore, higher concentrations of cortisol produced a smaller inhibition
of α-lactalbumin accumulation as compared to that obtained in cultures containing 5 μg/ml prolactin. The maximal increase
in α-lactalbumin accumulation attained in the presence of 1.4×10−8
M cortisol, 0.5 μg/ml prolactin, and insulin was comparable to that observed in culture containing 5 μg/ml prolactin and insulin.
Similar results were obtained in a cortisol concentration-response study of α-lactalbumin accumulation in cultures containing
a suboptimal concentration of 0.5 μg/ml human placental lactogen. Measurement of the rate of α-lactalbumin synthesis in cultured
tissue indicated that the opposing effects of low and high concentrations of cortisol on α-lactalbumin accumulation involved
an alteration in the rate of synthesis of the milk protein. In contrast to α-lactalbumin, the synthesis of casein was stimulated
in a concentration-dependent manner by addition of cortisol that acted synergistically with either 0.5 μg/ml or 5 μg/ml prolactin.
The maximal increases were obtained in the presence of 2.8×10−6
M cortisol. These results indicated that the action of cortisol on α-lactalbumin accumulation can be modulated by the concentration,
of prolactin and suggest that the interplay between cortisol and prolactin in regulation of α-lactalbumin synthesis may be
different from that involved in casein synthesis. 相似文献
123.
Reducing effect of ingesting tannic acid on the absorption of iron, but not of zinc, copper and manganese by rats 总被引:1,自引:0,他引:1
Interest in the beneficial effects of polyphenols, including tannic acid (TA), is increasing, although, these compounds also have adverse effects; for example, on the absorption of iron (Fe), and possibly other trace minerals. We examined the effect of a graded dose of TA on the absorption of Fe and compared with that of zinc (Zn), copper (Cu) and manganese (Mn) in rats. We also investigated the effect of TA on cecal fermentation which plays a role in absorption. In Experiment 1, to set the optimum dose of Fe, male Sprague-Dawley rats (weighing 70-90 g) after acclimatization were fed with different levels of dietary Fe (5, 10, 20, 30 and 35 mg/kg). We observed that the hematocrit (Ht), serum Fe concentration and transferrin saturation (%) were each reduced in those rats fed less than 20 mg/kg Fe in a dose-dependent manner. In Experiment 2, the rats were fed with test diets containing the minimum required level of Fe, 30 mg/kg diet, with (5, 10, 15 and 20 g/kg diet) or without TA for a period of three weeks. Feeding a diet containing more than 10 g TA/kg diet, but not 5 g TA/kg diet, reduced the hemoglobin concentration (Hb), Ht and serum Fe concentration due to decreased Fe absorption. In contrast, the Zn, Cu and Mn absorption was not affected by TA feeding. It is also demonstrated that liver Fe, but not the Zn, Cu and Mn contents, were lower in the TA groups than in the TA-free control group. Feeding TA slightly decreased the pH value of the cecal contents with an increase in the major short-chain fatty acid pool. About 15% of the ingested TA were recovered in the feces of each TA-fed group. Our results demonstrate that more than 10 g TA/kg diet induced anemia by reducing the Fe absorption, although there was no effect on the absorption of other important trace minerals. Our findings suggest that the usual intake of polyphenols is relatively safe, but that a high intake by supplementation or by dietary habit of tannin affects only the Fe level. 相似文献
124.
125.
Takamoto K Kawada M Usui T Ishizuka M Ikeda D 《Biochemical and biophysical research communications》2003,308(4):866-871
Nephrotoxicity is known to be a major clinical side effect of aminoglycoside antibiotics. Aminoglycosides cause damage to proximal tubular cells in kidney, however the mechanism of toxicity is still unclear. In order to elucidate the mechanism of nephrotoxicity, we studied the effect of aminoglycoside antibiotics on glucose transport systems in vitro and in vivo. As a result, we found that the aminoglycosides significantly reduced Na(+)/glucose cotransporter (SGLT1)-dependent glucose transport and also down-regulated mRNA and protein levels of the SGLT1 in pig proximal tubular LLC-PK(1) cells. To obtain evidence about SGLT1 down-regulation in vivo, we studied the mRNA expression of SGLT1 using gentamicin C-treated murine kidney and found that gentamicin C down-regulated SGLT1 in vivo as well as in vitro. Furthermore, the gentamicin C-treated mice showed significant rise in urinary glucose excretion. These results indicate that one of the mechanisms of aminoglycoside nephrotoxicity is the down-regulation of SGLT1, which causes reduction in glucose reabsorption in kidney. 相似文献
126.
AimsAs the clinical use of induced pluripotent stem (iPS) cells may have the potential to overcome current obstacles in stem cell-based therapy, the molecular mechanisms that regulate the proliferation of iPS cells are of great interest. However, to our knowledge, no previous studies have examined whether stimulation with nicotinic acetylcholine receptor (nAchR) enhances the growth of iPS cells. In the present study, we examined the involvement of nAchR in the proliferation of mouse iPS cells.Main methodsWe performed immunofluorescence staining to determine whether mouse iPS cells could express nAchRs. Mouse iPS cells were treated with nicotine for 24 h under feeder-free conditions in the presence of leukemia inhibitory factor (LIF). The DNA synthesis was examined by the BrdU incorporation assay. Intracellular calcium levels were measured using Fluo-4-acetoxymethyl (a cell-permeable calcium indicator). In addition, we examined the involvement of the CaMKП pathway in nicotine-enhanced proliferation of mouse iPS cells.Key findingsThe fluorescence images revealed that α4-nAchR and α7-nAchR are expressed on mouse iPS cells. Treatment of the cells with 300 nM nicotine significantly increases DNA synthesis. This is significantly inhibited by pretreatment with antagonists of α4-nAchR and α7-nAchR or a CaMKП inhibitor. In addition, treatment with nicotine increases the intracellular Ca2+ level dose-dependently in mouse iPS cells. Treatment with nicotine significantly enhances CaMKП phosphorylation.SignificanceThe present study indicates that stimulation of α4-nAchR and α7-nAchR may lead to a significant increase in the rate of mouse iPS cell proliferation through enhancement of the CaMKП signaling pathway. 相似文献
127.
K. Yamada H. Matsumoto K. Ishizuka K. Miyamoto S. Kosemura S. Yamamura K. Hasegawa 《Journal of Plant Growth Regulation》1998,17(4):215-219
The effect of disaccharide lepidimoide on light-induced chlorophyll accumulation was studied in cotyledons of sunflower (Helianthus annuus L.) seedlings and detached cucumber (Cucumis sativus L.) cotyledons. From studies on the structure-activity relationships of lepidimoide, its analogs, and sucrose with respect
to light-induced chlorophyll accumulation in the cotyledons of sunflower seedlings, both lepidimoide and the free carboxylic
acid of lepidimoide (lepidimoic acid) showed the highest promoting activity, whereas the hydrogenated lepidimoide, which lacks
a double bond in the C4, 5 position in uronic acid, showed lower activity than lepidimoide; however, sucrose exhibited very
weak activity. These results suggest that lepidimoide acts as a new type of plant growth regulator, not simply as a carbon
source providing energy. Lepidimoide promoted not only light-induced chlorophyll accumulation in sunflower cotyledons but
also light-induced 5-aminolevulinic acid content, which is considered to be a rate-limiting step in chlorophyll biosynthesis.
Lepidimoide with cytokinin stimulated the accumulation of chlorophyll and 5-aminolevulinic acid additively. In detached cucumber
cotyledons, lepidimoide also promoted light-induced chlorophyll accumulation. These results indicate that lepidimoide, in
cooperation with cytokinin, causes light-induced chlorophyll accumulation in the cotyledons of several dicot plant species
by affecting the level of 5-aminolevulinic acid.
Received April 4, 1997; accepted September 28, 1998 相似文献
128.
Paired box gene 5 isoforms A and B have different functions in transcriptional regulation of B cell development‐related genes in immature B cells 下载免费PDF全文
129.
Early‐shared Mycobacterium bovis bacillus Calmette–Guérin sub‐strains induce Th1 cytokine production in vivo 下载免费PDF全文
Keiichi Taniguchi Yuuji Miyatake Daisuke Hayashi Atsuro Takami Saotomo Itoh Saburo Yamamoto Shigeaki Hida Kikuo Onozaki Takemasa Takii 《Microbiology and immunology》2015,59(11):684-689
130.
Nakaaki Kawamata Baohui Xu Hiroo Nishijima Kohji Aoyama Mayumi Kusumoto Toru Takeuchi Chuwa Tei Sara A Michie Takami Matsuyama 《Respiratory research》2009,10(1):1-11