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DOI： 10.1677/joe.0.1780071

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DOI： 10.2108/zsj.20.639

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記述言語：英語  

Estrogen stimulates the proliferation of pituitary cells, in particular mammotrophs. The present study was designed to clarify involvement of transforming growth factor α (TGF-α) in the estrogen-induced growth of mouse pituitary cells in vitro. Anterior pituitary cells obtained from ICR male mice were cultured in a primary, serum-free culture system. Proliferation of pituitary cells was detected by monitoring the cellular uptake of a thymidine analogue, bromodeoxyuridine. Secretory cell types were immunocytochemically determined. Treatment with TGF-α (0.1 and 1 ng/ml) for 5 days stimulated cell proliferation. Since TGF-α binds to the epidermal growth factor (EGF)-receptor, this action may be exerted through this receptor. Estradiol-17β (E2, 10-9M) stimulated proliferation of mammotrophs. RG-13022, an EGF receptor inhibitor, reduced the cell proliferation induced by EGF or E2, showing that the EGF receptor was involved in this induction of mammotroph growth. Treatment with TGF-α antisense oligodeoxynucleotide (ODN) inhibited the cell proliferation induced by E2, but treatment with EGF antisense ODN did not. Dual detection of TGF-α mRNA and growth hormone by in situ hybridization and fluorescenceimmunocytochemistry demonstrated that TGF-α mRNA was detected in most somatotrophs. Our recent RT-PCR analysis revealed that E2 stimulated TGF-α-mRNA and EGF-receptor mRNA expression. These results indicate that TGF-α produced in somatotrophs mediates the stimulatory effect of estrogen on pituitary cell proliferation in a paracrine manner, and that EGF-receptor expression is stimulated by estrogen. These findings indicate that intrapituitary cell-to-cell interaction plays an important role in the control of pituitary secretory cells.

DOI： 10.1076/apab.110.1.34.895

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PubMed

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DOI： 10.1262/jrd.48.49

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DOI： 10.2108/zsj.19.789

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記述言語：英語   出版者・発行元：SOC ENDOCRINOLOGY  

The presence and possible physiological roles of alpha -melanocyte-stimulating hormone (alpha -MSH) in the peripheral tissues of birds have not been established. By a combination of RT-PCR, immunocytochemistry and in situ hybridization, we have examined alpha -MSH expression in the eye of the chicken during development. In the 1-day-old chick, alpha -MSH was expressed in the retinal pigment epithelial (RPE) cells, and also at a lower level in the cone cells. The melanocortin receptor subtypes, CMC1, CMC4 and CMC5, were expressed in the layers of the choroid and the neural retina, but not in the RPE cells. It is probable that the RPE cells secrete alpha -MSH to exert paracrine effects on the choroid and neural retina. During embryonic development, alpha -MSH immunoreactivity in the RPE cells was initially detected at embryonic day 10, and increased in intensity as development proceeded. No cone cells were stained with anti-alpha -MSH antiserum in any of the embryonic stages tested. The immunoreactivities for two prohormone convertases, PC1 and PC2, were co-localized to the RPE cells with a pattern of staining similar to that of alpha -MSH. Despite containing alpha -MSH immunoreactivity, the RPE cells in 1-day-old chicks expressed no immunoreactivity for the endoproteases. Furthermore, in a 3-day-old chick, proopiomelanocortin mRNA was detectable by in situ hybridization only in the, photoreceptor layer and not in the RPE cells. These results suggest that the RPE cells and the cone cells are intraocular sources of alpha -MSH in the embryonic and postnatal life of the chicken respectively. Embryonic expression of alpha -MSH in the RPE cells implies a possible role for the peptide in ocular development.

DOI： 10.1677/joe.0.1680527

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DOI： 10.1002/mrd.1112

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DOI： 10.1210/en.142.12.5158

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記述言語：英語   出版者・発行元：ZOOLOGICAL SOC JAPAN  

Epidermal growth factor (EGF) is one of growth factors that are thought to mediate the stimulatory effects of estrogen on the proliferation of uterine epithelial cells. The present study was attempted to obtain direct evidence for the mitogenic effects of EGF on uterine epithelial cells, and to prove that EGF and EGF receptors are expressed in these cells. Mouse uterine epithelial cells were isolated from immature female mice and cultured with or without EGF for 5 days. EGF (1 to 100 ng/ml) significantly increased the number of uterine epithelial cells, and the maximal growth (141.9+/-8.3% of controls) was obtained at a dose of 10 ng/ml. In addition, EGF (0.1 to 100 ng/ml) increased the number of DNA-synthesizing cells immunocytochemically detected by bromodeoxyuridine uptake to the nucleus. Northern blot analysis revealed that the uterine epithelial cells expressed both EGF mRNA (4.7 kb) and EGF receptor mRNAs (10.5, 6.6, and 2.7 kb) These results suggest that the proliferation of uterine epithelial cells is regulated by the paracrine and/ or autocrine action of EGF. Our previous study demonstrated the mitogenic effect of IGF-I on uterine epithelial cells. To examine whether the EGF- and IGF-I signaling act at the same level in the regulation of the proliferation of uterine epithelial cells, the cultured cells were simultaneously treated with IGF-I and EGF. IGF-I was found to additively stimulate the mitogenic effects of EGF, suggesting that the EGF-induced growth of uterine epithelial cells is distinct from IGF-l-induced growth.

DOI： 10.2108/zsj.17.661

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記述言語：英語   出版者・発行元：SOC ENDOCRINOLOGY  

Oestrogen stimulates the proliferation of pituitary cells. The present study was designed to clarify the involvement of transforming growth factor-alpha (TGF-alpha) in the oestrogen-induced growth of mouse pituitary cells in vitro. Anterior pituitary cells obtained from ICR male mice were cultured in a primary serum-free culture system. Proliferation of pituitary cells was detected by monitoring the cellular uptake of bromodeoxyuridine. Secretory cell types were immunocytochemically determined. Treatment with TGF-alpha (0.1 and 1 ng/ml) for 5 days stimulated cell proliferation. Since TGF-alpha binds to the epidermal growth factor (EGF) receptor, this action may be exerted through the EGF receptor. Oestradiol-17 beta (OE2, 10(-9) M) stimulated mammotrophic and corticotrophic cell proliferation. RG-13022, an EGF receptor inhibitor, inhibited the cell proliferation induced by EGF or OE2, showing that the EGF receptor was involved in the growth response in mammotrophs and corticotrophs. Treatment with antisense TGF-alpha oligodeoxynucleotide (ODN) inhibited the cell proliferation induced by OE2, but treatment with antisense EGF ODN did not. RT-PCR analysis revealed that OE2 stimulated TGF-alpha mRNA and EGF receptor mRNA expression. These results indicate that TGF-alpha mediates the stimulatory effect of oestrogen on the pituitary cell proliferation in a paracrine or autocrine manner, and that EGF receptor expression is stimulated by oestrogen.

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記述言語：英語   出版者・発行元：ELSEVIER SCIENCE BV  

Agouti-related protein (AGRP) is a naturally occurring antagonist of melanocortin action. It is expressed mainly in the arcuate nucleus where it plays an important role in the hypothalamic control of feeding and energy homeostasis by antagonism of central melanocortin 4 receptors in mammals. Besides in the brain, the melanocortin 4 receptor is expressed in numerous peripheral tissues in the chicken. To examine whether or not the peripheral melanocortin 4 receptor signaling could be regulated by AGRP, we cloned and localized the expression of the AGRP gene in the chicken. The chicken AGRP gene was found to encode a 154 or 165 amino acid protein, depending on the usage of two alternative translation initiation sites. The coding sequence consisted of three exons, like that of mammalian species. The C-terminal cysteine-rich region of the predicted AGRP displayed high levels of identity to mammalian counterparts (78-84%) and all 10 cysteine residues conferring functional conformation of AGRP were conserved; however, other regions showed apparently no homology, suggesting that biological activities of AGRP are located in its C-terminal region. RT-PCR analysis detected the AGRP mRNA in all tissues examined: the brain, adrenal gland, heart, liver, spleen, gonads, kidney, uropygial gland, skeletal muscle and adipose tissues. Interestingly, the skin also expressed the AGRP mRNA, where Agouti, another melanocortin receptor antagonist regulating hair pigmentation, is expressed in rodents. Most of those AGRP-expressing tissues have been demonstrated to express melanocortin 4 receptors and/or other subtypes of melanocortin receptor whose mammalian counterparts can bind AGRP. These results imply the possibility that some peripheral melanocortin systems could be regulated by the functional interaction between melanocortins and AGRP at melanocortin receptors in the chicken. (C) 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0167-4889(00)00022-7

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記述言語：英語   出版者・発行元：MUNKSGAARD INT PUBL LTD  

The 5' upstream regulatory region of the mouse tyrosinase gene contains a long (GA)n sequence, that may be capable of adopting a triple-helical conformation (triplex), We analyzed protein-DNA interactions in a part of the 5' upstream region containing the (GA)n sequence by gel retardation analysis and found evidence for a cell type-specific protein(s) that bound to this region. We also found a (TC)(10) sequence about 100 bp downstream from a polyadenylation site of the gene. Examination of tyrosinase cDNAs and Northern analysis indicated that this sequence is transcribed and removed during 3' end-processing of the mRNA, Based on the hypothesis that the (TC)(10) sequence binds to the (GA)n sequence and forms an intermolecular tripler, we performed the same gel retardation assay in the presence of the 3' non-coding RNA fragments containing the (UC)(10) sequence. The probe DNA failed to interact,vith the cell type-specific protein(s), These results suggest a novel hypothesis for the regulation of the mouse tyrosinase gene, i.e. that the 3' non-coding RNA fragments of mouse tyrosinase transcripts suppress its own expression at the transcriptional level. This might occur by preventing cell type-specific protein factor(s) from binding to the regulatory cis-elements in the 5' upstream region of the gene, possibly through a tripler formation, although this hypothesis remains to be proven.

DOI： 10.1034/j.1600-0749.2000.130209.x

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記述言語：英語   出版者・発行元：KARGER  

Epidermal growth factor (EGF) produced within the pituitary gland is associated with the growth of pituitary cells in rats. The aim of the present study was to localize EGF- and EGF receptor-expressing cells, and to clarify the involvement of EGF in DNA replication in 2-month-old male mouse pituitary cells, In situ hybridization of the pituitaries of these mice demonstrated that EGF mRNA was expressed in the anterior and intermediate lobes. Within the anterior pituitary, EGF mRNA-expressing cells were medium-sized and round, and made up 40% of the total number of secretory cells. EGF receptor mRNA was only detected in anterior pituitary cells. Forty-seven percent anterior pituitary cells expressed EGF receptor mRNA, An immunocytochemical study showed that most somatotropes and some mammotropes expressed EGF mRNA, When anterior pituitary cells were enzymatically dissociated and cultured in serum-free medium, RT-PCR demonstrated both EGF mRNA and EGF receptor mRNA expression. Treatment with EGF (1 and 10 ng/ml) for 5 days stimulated DNA replication in mammotropes and corticotropes, These results indicate that the DNA replication in mammotropes and corticotropes is regulated by the paracrine and/or autocrine activity of EGF produced at least in part by these cell types themselves. Copyright (C) 2000 S. Karger AG, Basel.

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記述言語：英語   出版者・発行元：SPRINGER VERLAG  

Pituitary tumor GH3 cells synthesize and secrete both growth hormone (GH) and prolactin (PRL). Morphological and functional changes of GH3 cells induced by epidermal growth factor (EGF, 10 nM), insulin (300 nM), and estradiol-17 beta (E2, 1 nM) were studied. Treatment of cultures of GH3 cells for 6 days with EGF, insulin, or E2 alone, and with EGF plus E2 did not affect the total number of GH3 cells, but a combination of EGF, insulin, and E2 decreased the total number of GH3 cells compared with control treatment. DNA-synthesizing cells were detected by monitoring 5-bromo-2'-deoxyuridine (BrdU) uptake. EGF, E2, or a combination of EGF, insulin, and E2 significantly decreased the proportion of BrdU-labeled cells (21.1+/-1.7%, 21.0+/-1.4%, 18.2+/-1.3%; P<0.05, P<0.05, P<0.01, respectively) compared with control treatment (28.6+/-1.5%), but insulin did not (31.4+/-2.4%). Immunocytochemical analysis of GH3 cells cultured in 5% fetal calf serum-supplemented medium (control) showed that about 70% of all GH3 cells were GH-immunoreactive cells (GH-ir cells), apparently containing only GH, and 14% were mammosomatotrophs (MS cells), containing both GH and PRL, while PRL-immunoreactive cells (PRL-ir cells), containing only PRL, were not detected. No GH or PRL immunoreactivity could be detected in the remaining cells (15%). EGF decreased the proportion of GH-ir cells. The effects of EGF were enhanced by simultaneous exposure to insulin and E2; this decreased the proportion of GH-ir cells to about 20% of the total GH3 cells and significantly increased the proportion of MS cells to 300% of controls. Treatment with EGF plus insulin, EGF plus E2, or a combination of EGF, insulin, and E2 all stimulated the appearance of PRL-ir cells. Exposure to EGF caused a significant decrease in GH mRNA (P<0.01) and a significant increase in PRL mRNA (P<0.05). These observations suggest that EGF is closely involved in differentiation of PRL-ir cells from GH-ir cells via MS cells in GH3 cell cultures. Cytosine arabinoside (10(-7) M), an inhibitor of cell division, did not affect the changes in proportion of the three cell types induced by treatment with a combination of EGF, insulin, and E2. It is therefore probable that the transdifferentiation does not require mitosis of the GH3 cells.

DOI： 10.1007/s004410050021

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記述言語：英語   出版者・発行元：ELSEVIER SCIENCE BV  

The gene for pro-opiomelanocortin (POMC), a common precursor of melanocortins, lipotropins and beta-endorphin, was isolated in the chicken first among avian species. The chicken POMC gene was found to be a single copy gene and appeared to show the same structural organization as that of other species of different classes. The predicted POMC displayed the highest identity to Xenopus POMC(A) (60.1%), and consisted of 251 amino acid residues with nine proteolytic cleavage sites, suggesting that it could be processed to give rise to all members of the melanocortin family, including adrenocorticotropic hormone and alpha-, beta- and gamma-melanocyte-stimulating hormones, as well as the other POMC-derived peptides. RT-PCR analysis detected the POMC mRNA in the brain, adrenal gland, gonads, kidney, uropygial gland and adipose tissues, each of which has been demonstrated to express melanocortin receptors. These results suggest that melanocortins act in a paracrine and/or autocrine manner to control a variety of functions both in the brain and in the peripheral tissues in the chicken. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0167-4889(99)00046-4

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記述言語：英語   出版者・発行元：ELSEVIER SCIENCE BV  

The melanocortin 3 receptor (MC3-R) in the melanocortin receptor family has been identified as a neural receptor subtype mainly expressed in the brain in mammals. We report here the isolation of the chicken gene for MC3-R, CMC3, displaying different tissue distribution from mammalian counterparts. The CMC3 gene was found to be a single copy gene encoding a 325 amino acid protein, sharing 75.3-76.8% identity with mammalian counterparts. When assessed by RT-PCR, the CMC3 mRNA was not detected in the brain but was exclusively expressed in adrenal glands, where Agouti-related protein/Agouti-related transcript (AGRP/ART), a newly identified endogenous antagonist of MC3-R, is expressed in mammals, raising the possibility that the CMC3 plays a role in complicated regulation of the gland function by melanocortins and AGRP/ART in the chicken. Noteworthy, MC1-R gene was found to be a quite unique member of the chicken MC-R family with regard to GC content and codon usage. It may reflect as yet unidentified evolutionary pressure operating specifically on the gene. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0167-4889(98)00165-7

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記述言語：英語   出版者・発行元：ACADEMIC PRESS INC  

Two receptor genes belonging to the melanocortin receptor (MC-R) family were isolated in the chicken, the CMC4 and CMC5, each of which is a chicken homologue of the mammalian MC4-R and MC5-R, respectively. The CMC4 encodes a 331 amino acid protein, sharing 86.4-88.1% identity with mammalian analogs, and the CMC5 encodes a 325 amino acid protein, which is 72.3-79.1% identical to mammalian counterparts. Both genes contain no intron in their coding regions and exist in the chicken genome as single copy genes. Reverse transcription-PCR analysis revealed that the CMC4 mRNA is expressed in a nide variety of peripheral tissues, including the adrenal, gonads, spleen, and adipose tissues, as well as in the brain, where mammalian counterparts are exclusively expressed in the brain, indicating that the regulation of MC4-R gene expression differs between mammals and chickens. The CMC5 mRNA, on the other hand, is expressed in the liver, gonads, adrenal, kidney brain, and adipose tissues as well as in the uropygial gland. These findings raise the possibility that melanocortins affect a variety of functions both in the brain and in the peripheral tissues of the chicken. (C) 1998 Academic Press.

DOI： 10.1006/gcen.1998.7167

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記述言語：英語   出版者・発行元：ZOOLOGICAL SOC JAPAN  

Insulin-like growth factor-I (IGF-I) is produced in the liver and other peripheral tissues in response to growth hormone (GH) stimuli. IGF-I regulates diverse physiological functions in an autocrine and/or paracrine manner. IGF-I and IGF-I receptor (type-I receptor) are expressed in human and rat pituitary glands. However, the cell types of IGF-I-expressing cells and target cells of IGF-I in the pituitary glands are not known. The present study was aimed to identify the cell types of IGF-I-expressing cells and of its type-I receptor-expressing cells in mouse pituitary glands. In the mouse pituitary glands, IGF-I mRNA and IGF-I receptor mRNA were detected by reverse transcription-polymerase chain reaction (RT-PCR). IGF-I-expressing cells and its receptor-expressing cells were detected by non-radioisotopic in situ hybridization using mouse IGF-I cDNA and IGF-I receptor cDNA probes, and their cell types were immunocytochemically determined using antibodies raised against pituitary hormones. We found that somatotrophs expressed both IGF-I and IGF-I receptors, and some of corticotrophs expressed IGF-I receptors. Co-localization of IGF-I and GH in the same cultured pituitary cells was observed by dual-labelling immunocytochemistry. The present study demonstrated that pituitary IGF-I produced in somatotrophs regulated functions of somatotrophs and corticotrophs in an autocrine and/or paracrine manner.

DOI： 10.2108/zsj.15.573

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記述言語：英語   出版者・発行元：J ENDOCRINOLOGY LTD  

IGF-I is synthesized in the human and rat anterior pituitary glands. The present study was designed to clarify the growth-promoting action of IGF-I on mouse pituitary cells in a primary serum-free culture system. Proliferation of pituitary cells was detected by monitoring the cellular uptake of bromodeoxyuridine (BrdU). BrdU labelling in the nucleus was found in all types of secretory cells: corticotrophs, thyrotrophs, gonadotrophs (LH cells and FSH cells), somatotrophs and mammotrophs. IGF-I (75 ng/ml) stimulated the proliferation of corticotrophs and mammotrophs among the pituitary secretory cells. IGF-I receptor mRNA was detected in the cultured pituitary cells using reverse transcription (RT)-PCR, indicating that mouse pituitary cells expressed IGF-I receptors. Insulin (100 ng/ml) or IGF-I (7.5 ng/ml) failed to increase the percentage of BrdU-labelled cells. However, treatment with insulin (100 ng/ml) plus IGF-I (7.5 ng/ml) increased the percentage of BrdU-labelled cells in a synergistic-like manner. Genistein, a tyrosine kinase specific inhibitor, decreased the IGF-I-induced cell proliferation, indicating that IGF-I acts through IGF-I receptors. IGF-I mRNA was also detected in the cultured pituitary cells by RT-PCR, and its peptides were immunocytochemically detected. The present results demonstrate that all types of pituitary secretory cells have the ability to proliferate in our serum-free culture system. IGF-I synthesized in the pituitary gland may stimulate the growth of pituitary cells, in particular corticotrophs and mammotrophs, by an autocrine or paracrine mechanism.

DOI： 10.1677/joe.0.1570053

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DOI： 10.2108/zsj.15.567

CiNii Article

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DOI： 10.1023/A:1009269830117

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DOI： 10.1016/S0167-4889(98)00022-6

CiNii Article

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DOI： 10.2220/biomedres.19.269

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DOI： 10.11477/mf.2425901240

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記述言語：英語   出版者・発行元：ELSEVIER SCIENCE BV  

The Extended black (E) locus on chromosome 1 acts within the melanocyte to regulate feather color pigmentation in the chicken. Several alleles exhibiting different pigmentation have been described and their phenotypes are similar to those of the murine extension locus which encodes melanocortin 1-receptor (MC1-R), the receptor for alpha-melanocyte-stimulating hormone (alpha-MSH). To investigate whether the MC1-R gene is responsible for E-locus function, we examined the structure of MC1-R in E-locus mutants by RFLP analysis and genomic DNA sequencing. In the most recessive allele (e(y)), which exhibits a uniformly red-yellow pigmentation, MC1-R was found to contain amino acid substitutions possibly causing functional deficiency. On the other hand, in the most dominant allele (E), which confers a uniformly black pigmentation, MC1-R possessed mutation responsible for a constitutively active MC1-R and resultant black coat color in mice. Our finding that the structure of MC1-R was affected by individual E-locus alleles strongly suggests that MC1-R is associated with the E-locus. Furthermore, since the same mutation of MC1-R was found in mice and chickens that exhibit the same pigmentation, it is possible that the regulatory mechanism of MC1-R function is shared in chickens and mammals.

DOI： 10.1016/0167-4781(96)00100-5

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記述言語：英語   出版者・発行元：ELSEVIER SCIENCE BV  

The chick melanocortin 1-receptor gene was isolated. It is found to be an intronless gene encoding a 314 amino acid protein, sharing 64% identity with mammalian counterparts. A cis-element responsible for melanocyte-specific transcription is found in its 5' upstream region. It is probable that the expression of the receptor in melanocytes is closely correlated with that of melanogenesis-related genes.

DOI： 10.1016/0167-4781(96)00026-7

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DOI： 10.2220/biomedres.13.253

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DOI： 10.1266/jjg.64.121

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DOI： 10.1016/S0006-291X(88)81110-0

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DOI： 10.1266/jjg.62.271

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