• Molecules and Cells
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• v.47 no.1
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• pp.100004.1-100004.11
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• 2024

Insulin is essential for maintaining normoglycemia and is predominantly secreted in response to glucose stimulation by β-cells. Incretin hormones, such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide, also stimulate insulin secretion. However, as obesity and type 2 diabetes worsen, glucose-dependent insulinotropic polypeptide loses its insulinotropic efficacy, whereas GLP-1 receptor (GLP-1R) agonists continue to be effective owing to its signaling switch from Gs to Gq. Herein, we demonstrated that endoplasmic reticulum (ER) stress induced a transition from Gs to Gq in GLP-1R signaling in mouse islets. Intriguingly, chemical chaperones known to alleviate ER stress, such as 4-PBA and TUDCA, enforced GLP-1R's Gq utilization rather than reversing GLP-1R's signaling switch induced by ER stress or obese and diabetic conditions. In addition, the activation of X-box binding protein 1 (XBP1) or activating transcription factor 6 (ATF6), 2 key ER stress-associated signaling (unfolded protein response) factors, promoted Gs utilization in GLP-1R signaling, whereas Gq employment by ER stress was unaffected by XBP1 or ATF6 activation. Our study revealed that ER stress and its associated signaling events alter GLP-1R's signaling, which can be used in type 2 diabetes treatment.

• Animal cells and systems
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• v.3 no.2
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• pp.193-197
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• 1999

A peroxidase-antiperoxidase method was used to detect the cells showing immunoreactivities to six hormone antibodies in the alimentary tracts of six frog species, Rana nigromaculata, R. rugosa, R. amurensis coreana, R. catesbeiana, Bombina orientalis, and Hyla arborea japonica, inhabiting Korea. The cells immunoreactive to gastrin and cholecystokinin-8 were observed in the pylorus of the stomachs and in the small intestines of all frog species examined. In contrast, these somatostatin-immunoreactive cells were identified in the esophagus and the whole gastrointestinal tracts, but were absent from the large intestines in R. rugosa, R. catesbeiana, B. orientalis and H. arborea japonica. The pancreatic polypeptide (PP)-immunoreactive cells represented their distribution limited to the small intestines of R. amurensis coreana and H. arborea japonica, and they were additionally identified in the pylorus of the stomachs in the other four species. Serotonin- and glucagon- Immunoreactive cells revealed different regional distributions in which the former were observed throughout the whole alimentary tracts in all frog species investigated, whereas the latter were not found in these regions at all. Endocrine cells were relatively abundant in the pyloric portion of the stomach compared to other organs. The present study showed that all endocrine cells except for PP had a similar distribution in the alimentary tracts of all frog species used.

• Journal of Life Science
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• v.9 no.2
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• pp.24-33
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• 1999

The gastrointestinal tract of three Percida, Lateolabrax japonicus, Epinephelus septemfasciatus and Mugil cephalus, was investigated immunocytochemically for the occurrence of somatostatin-. seotonin-, gastrin-, pancreatic polypeptide(PP)-, cholecystokinin-8(CCK-8)- and glucagon-immunoreactive cells. In Lateolabrax japonicus and Epinephelus septemfasciatus, five endorcrine cell types, such as somatostatin-, serotonin-, gastrin-, PP- and CCk-8-immunoreactive cells were demonstrated. In Mugil cephalus, however, six endocrine cell types, such as somatostatin-, serotnin-gastrin-, PP-, CCK-8- and glucagon-immunoreactive cells were detected. Somatostatin- and serotonin-immunoreactive cells were detected in the gastric mucosa of all species. Glucagon-immunoreactive cells were found only in the gastric mucoas of Mugil cephalus. In the pyloric caeca, PP-and CCK-8-immnuoreactive cells fo all species. gastrin-immunoreactive cells of Epinephelus septemfasciatus and Mugil cephalus, and serotonin-immunoreactive cells of Epinephelus septemfasciatus were demonstrated. In the intestinal mucosa of all species, gastrin-, PP- and CCK-8-immunoreactive cells were detected, and in the intestinal mucosa of Epinephelus septemfasciatus serotonin-immunoreactive cells were also detected. The frequency of these immunoreactive cells differs from each portion of the gastrointestinal tract of all species.

• Korean Journal of Veterinary Research
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• v.39 no.4
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• pp.689-697
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• 1999

The regional distribution and relative frequency of endocrine cells in the alimentary tract of the snake, Rhabdophis tigrinus tigrinus, were investigated by immunohistochemical method using 7 antisera. Chromogranin (Cg)-, glucagon-, somatostatin-, gastrin/cholecystokinin (Gas/CCK)-, serotonin-, bovine pancreatic polypeptide (BPP)-immunoreactive cells were identified in this study. Cg-immunoreactive cells were detected throughout the alimentary tract including the esophagus, with predominant frequency in the pylorus. Numerous immunoreactive cells were observed from the esophagus to the pylorus but a few cells were detected in the large intestine. Glucagon-immunoreactive cells were observed from the proximal portions to the distal portions of the small intestine. They were increased to the middle portions but thereafter decreased, and no cells were found in the terminal portions. Somatostatin-immunoreactive cells were restricted to the small intestine and these cells were decreased toward to distal portions of the small intestine. Gas/CCK-immunoreactive cells were detected in the pylorus and small intestine. They were most predominant in the pylorus and the proximal portions of the small intestine but thereafter decreased toward to the distal regions. Serotonin-immunoreactive cells were observed throughout the alimentary tract. They were most predominant in the pylorus and proximal portions of the small intestine but a few cells were observed in the large intestine. BPP-immunoreactive cells were restricted to the distal portions of the small intestine with rare frequency. No bombesin-immunoreactive cells were found in this study.

• The Korean Journal of Zoology
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• v.33 no.1
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• pp.119-125
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• 1990

A Potent inhibitor of trypsin and other various serine proteases including chymotrypsin, elastase, kallikrein, plasmin and subtilisin, has been purified to homogeneity from chick skeletal muscle by convendonal chromatographic procedures. The Inhibitor has an apparent molecular weight of 66, 000 dalton as determined by gel filtration. When the purified inhibitor was electrophoresed in the presence of sodium dodecyl sulfate, there appeared rwo protein bands having molecular weights of 66, 000 and 64, 000 dalton. The 64, 000 dalton protein seems to be the product of 66, 000 dalton protein by a lin'ited proteolysis during the purification procedure or in viuo. Thus, it seems to consist of a single polypeptide. The inhibitor appeared to be glycoprotein and have an isoelectric point of 7.4. It contains relatively large amount (8.33 mole%) of cysteine residues.

• Animal cells and systems
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• v.4 no.4
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• pp.375-379
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• 2000

The appearance of some gastrointestinal endocrine cells in the Meckel's diverticulum (MD) of the bean goose, Anser fabalis Latham was observed using specific antisera against serotonin, gastrin, cholecystokinin (CCK)-8, glucagon, secretin, somatostatin and human pancreatic polypeptide (HPP) with the peroxidase antiperoxidase (PAP) method. Among these specific antisera, serotonin-, gastrin-, CCK-8-, somatostatin- and HPP-immunoreactive cells were demonstrated in this study. Serotonin-, gastrin- and somatostatin-immunoreactive cells were detected at moderate frequency and CCK-8- and HPP-immunoreactive cells was rare and low frequencies, respectively. These immunoreactive cells were located in the superficial epithelium, intestinal crvpt and intestinal glands with spherical or spindle shaped cells having long cytoplasmic processes (open typed-cell). Mucosal layer of MD was composed of simple columnar epithelium and numerous intestinal glands. In addition, numerous lymphatic tissues were also demonstrated. In conclusion, histological profiles of MD were similar to any parts of the large intestine, especially the cecum, but the appearance, distribution and relative frequency of gastrointestinal endocrine cells were similar to those of upper parts of the small intestine. Although the exact digestive functions were unknown, the finding that the appearance, distribution and relative frequency of gastrointestinal endocrine cells in MD is similar to small intestine may be considered as distinct evidence that this organ may have some digestive functions.

• The Korean Journal of Zoology
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• v.33 no.3
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• pp.276-296
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• 1990

This study attempts to investigate several enteroendocrine cells in the gastrointestinal epithelia of the Korean snakes (Dinodon rufozonatum rufozonotum Rhabdophis tigrina tigrina, Enhydris rufodorsata, Agkistrodon blomhoffii brevicaudus, Agkistrodon saxatilis, Agkistodon calginosus). For a light-microscopical examination of immunocytochemistry, the paraffin sections (5 $\mu$ m) of tissue specimens taken from the various parts of the gastrointestinal tract were stained immunocytochemically by PAP procedure with 10 antisera. The frequency of enteroendocrine cells per unit area (mm$^2$) of each mucosa were counted and the shapes of the cells were observed. In Dinodon rufozonatum rufozonatum, Rhobdophis tigrina tigrina, Enhydris rufodorsata, Agkistrodon saxatilis and Agkistrodon caliginosus, cholecystokinin (CCK)-8, gastrin, pancreatic polypeptide (PP) and serotonin cells were observed. But the freuqency of these immunoreactive cells differ trom each portion of gastrointestinal tracts of all species, respectively. In Agkistrodon blomhoffii brevicaudus, CCK-8, gastrin and serotonin cells were observed. CCK-8 and serotonin cells were found in whole gastrointestinal tracts and gastrin cells were observed in pylorus and mucosa of small intestine. The frequency of these cells was different from each portion. The shapes of CCK-8, gastrin, PP and serotonin cells were pyramidal or oval and closed type in stomach. A large number of these cells were spindle in shape and open type in small intestine and anterior pant of large intestine, whereas some cells were closed type. In posterior part of large intestine and rectum, these cells were oval in shape and closed type.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.1
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• pp.1-6
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• 2010

Purpose: Chemokines are structurally related, small polypeptide signaling molecules that bind to and activate a family of transmembrane G protein-coupled receptors, the chemokine receptors. Recently, interaction between the chemokine receptor CXCR4 and its ligand, stromal cell-derived factor 1 (SDF-1 or CXCL12), has been found to play an important role in tumorigenicity, proliferation, metastasis and angiogenesis in many cancers such as lung cancer, breast cancer, melanoma, glioblastoma, pancreatic cancer and cholangiocarcinoma. Hence, the goal of this study is to identify the correlation of clinicopathological factors and the up-regulation of SDF-1 expression in oral squamous cell carcinoma. Material and methods: We studied the immunohistochemical staining of SDF-1, quantitative RT-PCR (qRT-PCR) of SDF-1 gene in 20 specimens of 20 patients with oral squamous cell carcinoma. Results: 1. In the immunohistochemical study of poor differentiated and invasive oral squamous cell carcinoma, the high level staining of SDF-1 was observed. And the correlation between immunohistochemical SDF-1 expression and tumor nodes metastases (TNM) classification of specimens was significant.($x^2$ test, P < 0.05) 2. In the SDF-1 gene qRT-PCR analysis, SDF-1 expression was more in tumor tissue than in carcinoma in situ tissue. Paired-samples analysis determined the difference of SDF-1 mRNA expression level between the cancer tissue and the carcinoma in situ tissue.(Student's t-test, P < 0.05) Conclusion: These findings suggest that up-regulation of the SDF-1 may play a role in progression and invasion of oral squamous cell carcinoma.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.448-454
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• 1999

The regional distribution and relative frequency of the endocrine cells in the pancreas of the bean goose were investigated by immunohistochemical methods using 6 types of the specific antisera. Spindle shaped serotonin-immunoreactive cells were detected in the exocrine portions. Spherical or spindle shaped glucagon-immunoreactive cells were observed in the exocrine and dark and mammalian type islets. In the dark type islets, numerous cells were dispersed throughout whole islets but they were located in the peripheral regions of the mammalian type islets. No glucagon-immunoreactive cells were detected in light type islets. Round or spherical shaped insulin-immunoreactive cells were observed in the exocrine and dark, light and mammalian type islets. They were observed in the exocrine regions with a few numbers. Extremely rare cells were detected in central portion of the dark type islets but moderate to numerous cells were found in the central regions of the mammalian and light type islets, respectively. Spherical or spindle shaped somatostatin-immunoreactive cells were observed in the exocrine and dark, light and mammalian type islets. A few single cells were detected in the exocrine portions. In the dark type islets, numerous cells were dispersed throughout whole islets but a few to moderate numbers of cells were located in the peripheral regions of the light and mammalian type islets. Moderate numbers of the bovine pancreatic polypeptide-immunoreactive cells were found in the exocrine portions with round, spherical or spindle shape. But no bovine Sp-1/chromogranin-immunoreactive cells were observed in this study.

• Journal of Pharmacopuncture
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• v.20 no.4
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• pp.235-242
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• 2017

Irisin is a novel hormone like polypeptide that is cleaved and secreted by an unknown protease from fibronectin type III domain-containing protein 5 (FNDC5), a membrane-spanning protein and which is highly expressed in skeletal muscle, heart, adipose tissue, and liver. Since its discovery in 2012, it has been the subject of many researches due to its potent physiological role. It is believed that understanding irisin's function may be the key to comprehend many diseases and their development. Irisin is a myokine that leads to increased energy expenditure by stimulating the 'browning' of white adipose tissue. In the first description of this hormone, increased levels of circulating irisin, which is cleaved from its precursor fibronectin type III domain-containing protein 5, were associated with improved glucose homeostasis by reducing insulin resistance. Irisin is a powerful messenger, sending the signal to determine the function of specific cells, like skeletal muscle, liver, pancreas, heart, fat and the brain. The action of irisin on different targeted tissues or organs in human being has revealed its physiological functions for promoting health or executing the regulation of variety of metabolic diseases. Numerous studies focus on the association of irisin with metabolic diseases which has gained great interest as a potential new target to combat type 2 diabetes mellitus and insulin resistance. Irisin is found to improve insulin resistance and type 2 diabetes by increasing sensitization of the insulin receptor in skeletal muscle and heart by improving hepatic glucose and lipid metabolism, promoting pancreatic ${\beta}$ cell functions, and transforming white adipose tissue to brown adipose tissue. This review is a thoughtful attempt to summarize the current knowledge of irisin and its effective role in mediating metabolic dysfunctions in insulin resistance and type 2 diabetes mellitus.