The Role of the Sweet Taste Receptor in Enteroendocrine Cells and Pancreatic β-Cells

Itaru Kojima,Yuko Nakagawa 대한당뇨병학회 2011 Diabetes and Metabolism Journal Vol.35 No.5

The sweet taste receptor is expressed in taste cells located in taste buds of the tongue. This receptor senses sweet substances in the oral cavity, activates taste cells, and transmits the taste signals to adjacent neurons. The sweet taste receptor is a heterodimer of two G protein-coupled receptors, T1R2 and T1R3. Recent studies have shown that this receptor is also expressed in the extragustatory system, including the gastrointestinal tract, pancreatic β-cells, and glucose-responsive neurons in the brain. In the intestine,the sweet taste receptor regulates secretion of incretin hormones and glucose uptake from the lumen. In β-cells, activation of the sweet taste receptor leads to stimulation of insulin secretion. Collectively, the sweet taste receptor plays an important role in recognition and metabolism of energy sources in the body.

Which is better for unresectable malignant hilar biliary obstruction: Side-by-side versus stent-in-stent?

Itaru Naitoh,Tadahisa Inoue,Kazuki Hayashi 소화기인터벤션의학회 2018 Gastrointestinal Intervention Vol.7 No.2

Biliary drainage is required for the management of unresectable malignant hilar biliary obstruction (UMHBO), and endoscopic transpapillary drainage is the first-line therapy because it is less invasive. Self-expandable metallic stents (SEMSs) are superior to plastic stents because they have longer stent patency and are more cost-effective. Endoscopic bilateral SEMS placement is technically challenging compared to unilateral placement. However, recent developments in devices and techniques have facilitated bilateral SEMS placement. There are two methods for bilateral hilar SEMS placement for UMHBO: side-by-side (SBS) and stent-in-stent (SIS). Sequential SBS was commonly conducted for bilateral hilar SEMS placement. In a new and thinner delivery system that was developed for SEM placement, two SEMSs could be simultaneously inserted and deployed through the working channel. This new bilateral stenting method enabled us to accomplish simultaneous SBS placement, which increased the success rate of SBS. Insertion of the guidewire and delivery of the second SEMS through the mesh of the first SEMS is challenging in SIS. Newly designed or modified SEMSs that are suitable for SIS have been developed to overcome this challenge, and these SEMSs have facilitated SIS. Uncovered SEMS has been commonly used for hilar SEMS placement, but covered SEMS (CSEMS) is another option for hilar SEMS placement, because CSEMS prevents tumor ingrowth and allows for removal of the stent for re-intervention. Therefore, CSEMS can be used for bilateral SEMS placement in SBS. There are many methods and kinds of SEMS available for bilateral SEMS placement. However, due to lack of evidence, there is no consensus on whether SBS or SIS is optimal for bilateral hilar SEMS placement. In this review, we compared various outcomes between SBS and SIS from previous studies, to clarify which method is better for bilateral SEMS placement for UMHBO.

EARLY MIOCENE PROTO-JAPAN SEA

ITARU KOIZUMI 한국고생물학회 1988 고생물학회지 Vol.4 No.1

Complications Related to Gastric Endoscopic Submucosal Dissection and Their Managements

Itaru Saito,Yosuke Tsuji,Yoshiki Sakaguchi,Keiko Niimi,Satoshi Ono,Shinya Kodashima,Nobutake Yamamichi,Mitsuhiro Fujishiro,Kazuhiko Koike 대한소화기내시경학회 2014 Clinical Endoscopy Vol.47 No.5

Endoscopic submucosal dissection (ESD) for early gastric cancer is a well-established procedure with the advantage of resection in an en bloc fashion, regardless of the size, shape, coexisting ulcer, and location of the lesion. However, gastric ESD is a more difficult and meticulous technique, and also requires a longer procedure time, than conventional endoscopic mucosal resection. These factors naturally increase the risk of various complications. The two most common complications accompanying gastric ESD are bleeding and perforation. These complications are known to occur both intraoperatively and postoperatively. However, there are other rare but serious complications related to gastric ESD, including aspiration pneumonia, stenosis, venous thromboembolism, and air embolism. Endoscopists should have sufficient knowledge about such complications and be prepared to deal with them appropriately, as successful management of complications is necessary for the successful completion of the entire ESD procedure.

The Optimal Surgical Method According to The Morphological Classification

Itaru Endo 대한외과학회 2019 대한외과학회 학술대회 초록집 Vol.2019 No.10

Sweet Taste-Sensing Receptors Expressed in Pancreatic ß-Cells: Sweet Molecules Act as Biased Agonists

Itaru Kojima,Yuko Nakagawa,Yoshiaki Ohtsu,Anya Medina,Masahiro Nagasawa 대한내분비학회 2014 Endocrinology and metabolism Vol.29 No.1

The sweet taste receptors present in the taste buds are heterodimers comprised of T1R2 and T1R3. This receptor is also expressed in pancreatic ß-cells. When the expression of receptor subunits is determined in ß-cells by quantitative reverse transcription polymerase chain reaction, the mRNA expression level of T1R2 is extremely low compared to that of T1R3. In fact, the expression of T1R2 is undetectable at the protein level. Furthermore, knockdown of T1R2 does not affect the effect of sweet molecules, whereas knockdown of T1R3 markedly attenuates the effect of sweet molecules. Consequently, a homodimer of T1R3 functions as a receptor sensing sweet molecules in ß-cells, which we designate as sweet taste-sensing receptors (STSRs). Various sweet molecules activate STSR in ß-cells and augment insulin secretion. With regard to intracellular signals, sweet molecules act on STSRs and increase cytoplasmic Ca2+ and/or cyclic AMP (cAMP). Specifically, when an STSR is stimulated by one of four different sweet molecules (sucralose, acesulfame potassium, sodium saccharin, or glycyrrhizin), distinct signaling pathways are activated. Patterns of changes in cytoplasmic Ca2+ and/or cAMP induced by these sweet molecules are all different from each other. Hence, sweet molecules activate STSRs by acting as biased agonists.

Classification and Diagnostic Criteria for IgG4-Related Sclerosing Cholangitis

( Itaru Naitoh ),( Takahiro Nakazawa ) 대한소화기학회 2022 Gut and Liver Vol.16 No.1

IgG4-related sclerosing cholangitis (IgG4-SC) can be classified into four types based on cholangiographic findings and regions of biliary stricture. This cholangiographic classification is useful to differentiate IgG4-SC from mimickers including cholangiocarcinoma, primary sclerosing cholangitis, and pancreatic cancer. Autoimmune pancreatitis (AIP) is a valuable clue for the diagnosis of IgG4-SC because the two are frequently found in association with each other. Two sets of diagnostic criteria for IgG4-SC have been proposed. In Japan, the clinical diagnostic criteria 2020 were recently developed. These clinical diagnostic criteria include narrowing of the intrahepatic and/or extrahepatic bile duct, thickening of the bile duct wall, serological findings, pathological findings, other organ involvement, and effectiveness of steroid therapy. When these criteria are applied, IgG4-SC is initially classified as associated or not associated with AIP, and cholangiographic classification is used for differential diagnosis. In most instances, IgG4-SC can be diagnosed on the basis of clinical diagnostic criteria. However, it is challenging to diagnose isolated IgG4-SC or IgG4-SC not associated with AIP. Here, we review the classification and diagnostic criteria for IgG4-SC, specifically focusing on the clinical diagnostic criteria 2020 and a large IgG4-SC case series from a nationwide survey in Japan. (Gut Liver 2022;16:28-36)

Conversion surgery following neoadjuvant therapy for advanced biliary tract cancer

Itaru ENDO 한국간담췌외과학회 2022 Annals of hepato-biliary-pancreatic surgery Vol.26 No.-

Which is better for unresectable malignant hilar biliary obstruction: Side-by-side versus stent-in-stent?

Itaru Naitoh,Tadahisa Inoue,Kazuki Hayashi 소화기인터벤션의학회 2018 International journal of gastrointestinal interven Vol.7 No.2

Biliary drainage is required for the management of unresectable malignant hilar biliary obstruction (UMHBO), and endoscopic transpapillary drainage is the first-line therapy because it is less invasive. Self-expandable metallic stents (SEMSs) are superior to plastic stents because they have longer stent patency and are more cost-effective. Endoscopic bilateral SEMS placement is technically challenging compared to unilateral placement. However, recent developments in devices and techniques have facilitated bilateral SEMS placement. There are two methods for bilateral hilar SEMS placement for UMHBO: side-by-side (SBS) and stent-in-stent (SIS). Sequential SBS was commonly conducted for bilateral hilar SEMS placement. In a new and thinner delivery system that was developed for SEM placement, two SEMSs could be simultaneously inserted and deployed through the working channel. This new bilateral stenting method enabled us to accomplish simultaneous SBS placement, which increased the success rate of SBS. Insertion of the guidewire and delivery of the second SEMS through the mesh of the first SEMS is challenging in SIS. Newly designed or modified SEMSs that are suitable for SIS have been developed to overcome this challenge, and these SEMSs have facilitated SIS. Uncovered SEMS has been commonly used for hilar SEMS placement, but covered SEMS (CSEMS) is another option for hilar SEMS placement, because CSEMS prevents tumor ingrowth and allows for removal of the stent for re-intervention. Therefore, CSEMS can be used for bilateral SEMS placement in SBS. There are many methods and kinds of SEMS available for bilateral SEMS placement. However, due to lack of evidence, there is no consensus on whether SBS or SIS is optimal for bilateral hilar SEMS placement. In this review, we compared various outcomes between SBS and SIS from previous studies, to clarify which method is better for bilateral SEMS placement for UMHBO.

Development of New Reliable Blowing Head with Buckling Detector for Air Blown Fiber System

Itaru Sakabe,Wataru Katsurashima,Hiroaki Sano,Shigeru Tanaka 한국통신학회 1997 OPTOELECTRONICS & COMMUNICATIONS CONFERENCE Vol.2 No.1