Publications by authors named "Hiroyuki Oshima"

15 Publications

  • Page 1 of 1

Development of Oral Care Chip, a novel device for quantitative detection of the oral microbiota associated with periodontal disease.

PLoS One 2020 28;15(2):e0229485. Epub 2020 Feb 28.

Department of Periodontology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan.

Periodontal disease, the most prevalent infectious disease in the world, is caused by biofilms formed in periodontal pockets. No specific bacterial species that can cause periodontitis alone has been found in any study to date. Several periodontopathic bacteria are associated with the progress of periodontal disease. Consequently, it is hypothesized that dysbiosis of subgingival microbiota may be a cause of periodontal disease. This study aimed to investigate the relationship between the subgingival microbiota and the clinical status of periodontal pockets in a quantitative and clinically applicable way with the newly developed Oral Care Chip. The Oral Care Chip is a DNA microarray tool with improved quantitative performance, that can be used in combination with competitive PCR to quantitatively detect 17 species of subgingival bacteria. Cluster analysis based on the similarity of each bacterial quantity was performed on 204 subgingival plaque samples collected from periodontitis patients and healthy volunteers. A significant difference in the number of total bacteria, Treponema denticola, Campylobacter rectus, Fusobacterium nucleatum, and Streptococcus intermedia bacteria in any combination of the three clusters indicated that these bacteria gradually increased in number from the stage before the pocket depth deepened. Conversely, Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, and Streptococcus constellatus, which had significant differences only in limited clusters, were thought to increase in number as the pocket depth deepened, after periodontal pocket formation. Furthermore, in clusters where healthy or mild periodontal disease sites were classified, there was no statistically significant difference in pocket depth, but the number of bacteria gradually increased from the stage before the pocket depth increased. This means that quantitative changes in these bacteria can be a predictor of the progress of periodontal tissue destruction, and this novel microbiological test using the Oral Care Chip could be effective at detecting dysbiosis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0229485PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7048280PMC
May 2020

Dimorphic sperm formation by .

Proc Natl Acad Sci U S A 2019 05 29;116(21):10412-10417. Epub 2019 Apr 29.

Division of Evolutionary Developmental Biology, National Institute for Basic Biology, Myodaiji, 444-8585 Okazaki, Japan;

Sex is determined by diverse mechanisms and master sex-determination genes are highly divergent, even among closely related species. Therefore, it is possible that homologs of master sex-determination genes might have alternative functions in different species. Herein, we focused on (), which is the master sex-determination gene in and is necessary for female germline development. It has been widely shown that the sex-determination function of in Drosophilidae species is not conserved in other insects of different orders. We investigated the function of in the lepidopteran insect In lepidopteran insects (moths and butterflies), spermatogenesis results in two different types of sperm: nucleated fertile eupyrene sperm and anucleate nonfertile parasperm, also known as apyrene sperm. Genetic analyses using mutants revealed that the gene is indispensable for proper morphogenesis of apyrene sperm. Similarly, our analyses using mutants clearly demonstrate that apyrene sperm are necessary for eupyrene sperm migration from the bursa copulatrix to the spermatheca. Therefore, apyrene sperm is necessary for successful fertilization of eupyrene sperm in Although is essential for oogenesis in , it also plays important roles in spermatogenesis in Therefore, the ancestral function of might be related to germline development.
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http://dx.doi.org/10.1073/pnas.1820101116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6535010PMC
May 2019

Desorption dynamics of CO from formate decomposition on Cu(111).

Chem Commun (Camb) 2017 Aug;53(66):9222-9225

Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871, Japan. and Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520, Japan and Research Center for Ultra-Precision Science and Technology, Graduate School of Engineering, Osaka University, Japan.

We performed ab initio molecular dynamics analysis of formate decomposition to CO and H on a Cu(111) surface using van der Waals density functionals. Our analysis shows that the desorbed CO has approximately twice larger bending vibrational energy than the translational, rotational, and stretching vibrational energies. Since formate synthesis, the reverse reaction of formate decomposition, has been suggested experimentally to occur via the Eley-Rideal mechanism, our results indicate that the formate synthesis can be enhanced if the bending vibrational mode of CO is excited rather than the translational and/or stretching vibrational modes. Detailed information on the energy distribution of desorbed CO as a formate decomposition product may provide new insights for improving the catalytic activity of formate synthesis.
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http://dx.doi.org/10.1039/c7cc03707dDOI Listing
August 2017

Comparison of the safety, tolerability, and pharmacokinetics of fidaxomicin in healthy Japanese and caucasian subjects.

Clin Drug Investig 2015 Jun;35(6):375-84

Astellas Pharma Inc., 2-5-1 Nihonbashi-Honcho, Chuo-ku, Tokyo, 103-8411, Japan,

Background And Objectives: Fidaxomicin treatment of Clostridium difficile infection is known to produce minimal systemic exposure, as the antibacterial (antibiotic) remains primarily in the gut. In this randomized, double-blind, placebo-controlled study, the safety, tolerability, and pharmacokinetics of single and multiple ascending doses of fidaxomicin were evaluated in healthy Japanese and Caucasian subjects.

Methods: Thirty-six healthy subjects were randomly assigned in a 3:1 ratio to receive either fidaxomicin or placebo. Cohort 1 (100 mg) and Cohort 2 (200 mg) comprised 12 Japanese subjects each and Cohort 3 (200 mg) comprised 12 Caucasian subjects. Subjects received a single dose of the study drug on Day 1 and received multiple doses for 10 days after a wash-out period.

Results: After multiple 200 mg dosing of fidaxomicin, both mean maximum plasma concentrations (C max) in Japanese (8.7 ± 5.3 ng/mL) and Caucasian (7.0 ± 3.7 ng/mL) subjects and the area under the concentration-time curve (AUC) were higher in Japanese subjects (58.5 ± 36.7 ng·h/mL) than in Caucasian subjects (37.6 ± 15.7 ng·h/mL), although variation in both groups was large. The mean fecal concentrations of fidaxomicin in Japanese and Caucasian subjects were 2669 and 2181 μg/g, respectively. The possibly study drug-related adverse events were diarrhea (n = 1), feeling hot (n = 1), and hypersomnia (n = 2), which were mild in severity.

Conclusions: In both Japanese and Caucasian subjects, fidaxomicin demonstrated similarly minimal systemic absorption, and was mainly excreted in feces. Fidaxomicin was safe and well-tolerated in all subjects.
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http://dx.doi.org/10.1007/s40261-015-0291-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4449367PMC
June 2015

Effect of additional preoperative administration of the neutrophil elastase inhibitor sivelestat on perioperative inflammatory response after pediatric heart surgery with cardiopulmonary bypass.

Artif Organs 2014 Dec 21;38(12):1018-23. Epub 2014 Apr 21.

Medical Engineering Center, Kitasato University School of Medicine, Sagamihara, Japan.

Cardiopulmonary bypass (CPB) elicits a systemic inflammatory response. Our previous reports revealed that prophylactic sivelestat administration at CPB initiation suppresses the postoperative acute inflammatory response due to CPB in pediatric cardiac surgery. The purpose of this study was to compare the effects of sivelestat administration before CPB and at CPB initiation in patients undergoing pediatric open-heart surgery. Twenty consecutive patients weighing 5-10 kg and undergoing ventricular septal defect closure with CPB were divided into pre-CPB (n = 10) and control (n = 10) groups. Patients in the pre-CPB group received a 24 h continuous intravenous infusion of 0.2 mg/kg/h sivelestat starting at the induction of anesthesia and an additional 0.1 mg/100 mL during CPB priming. Patients in the control group received a 24-h continuous intravenous infusion of 0.2 mg/kg/h sivelestat starting at the commencement of CPB. Blood samples were tested. Clinical variables including blood loss, water balance, systemic vascular resistance index, and the ratio between partial pressure of oxygen and fraction of inspired oxygen (P/F ratio) were assessed. White blood cell count and neutrophil count as well as C-reactive protein levels were significantly lower in the pre-CPB group according to repeated two-way analysis of variance, whereas platelet count was significantly higher. During CPB, mixed venous oxygen saturation remained significantly higher and lactate levels lower in the pre-CPB group. Postoperative alanine aminotransferase and blood urea nitrogen levels were significantly lower in the pre-CPB group than in the control group. The P/F ratio was significantly higher in the pre-CPB group than in the control group. Fluid load requirement was significantly lower in the pre-CPB group.Administration of sivelestat before CPB initiation is more effective than administration at initiation for the suppression of inflammatory responses due to CPB in pediatric open-heart surgery, with this effect being confirmed by clinical evidence.
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http://dx.doi.org/10.1111/aor.12311DOI Listing
December 2014

Chronic treatment with novel GPR40 agonists improve whole-body glucose metabolism based on the glucose-dependent insulin secretion.

J Pharmacol Exp Ther 2013 Sep 12;346(3):443-52. Epub 2013 Jul 12.

Pharmacology Research Laboratories, Drug Discovery Research, Astellas Pharma Inc, Tsukuba, Japan.

GPR40 is a free fatty acid receptor that has been shown to regulate glucose-dependent insulin secretion. This study aimed to discover novel GPR40 agonists and investigate the whole-body effect on glucose metabolism of GPR40 activation using these novel GPR40 agonists. To identify novel GPR40-specific agonists, we conducted high-throughput chemical compound screening and evaluated glucose-dependent insulin secretion. To investigate the whole-body effect on glucose metabolism of GPR40 activation, we conducted repeat administration of the novel GPR40 agonists to diabetic model ob/ob mice and evaluated metabolic parameters. To characterize the effect of the novel GPR40 agonists more deeply, we conducted an insulin tolerance test and a euglycemic-hyperinsulinemic clamp test. As a result, we discovered the novel GPR40-specific agonists, including AS2034178 [bis{2-[(4-{[4'-(2-hydroxyethoxy)-2'-methyl[1,1'-biphenyl]-3-yl]methoxy}phenyl)methyl]-3,5-dioxo-1,2,4-oxadiazolidin-4-ide} tetrahydrate], and found that its exhibited glucose-dependent insulin secretion enhancement both in vitro and in vivo. In addition, the compounds also decreased plasma glucose and HbA1c levels after repeat administration to ob/ob mice, with favorable oral absorption and pharmacokinetics. Repeat administration of AS2034178 enhanced insulin sensitivity in an insulin tolerance test and a euglycemic-hyperinsulinemic clamp test. These results indicate that improvement of glucose-dependent insulin secretion leads the improvement of whole-body glucose metabolism chronically. In conclusion, AS2034178 and other GPR40 agonists may become useful therapeutics in the treatment of type 2 diabetes mellitus.
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http://dx.doi.org/10.1124/jpet.113.206466DOI Listing
September 2013

Effect of the neutrophil elastase inhibitor sivelestat on perioperative inflammatory response after pediatric heart surgery with cardiopulmonary bypass: a prospective randomized study.

Artif Organs 2013 Dec 3;37(12):1027-33. Epub 2013 Jul 3.

Medical Engineer Center, Kitasato University School of Medicine, Sagamihara, Japan.

Cardiopulmonary bypass (CPB) elicits a systemic inflammatory response. The neutrophil elastase inhibitor sivelestat is known to suppress this systemic inflammatory response, which can eventually result in acute organ failure. The prophylactic effect of sivelestat on acute lung injury, especially in pediatric cardiac surgery, remains unclear. This prospective double-blind, randomized study evaluated the perioperative prophylactic effect of sivelestat in patients undergoing elective pediatric open heart surgery with CPB. Thirty consecutive patients, weighing 5-10 kg and undergoing open heart surgery with CPB, were assigned to sivelestat (n = 15) or control (n = 15) groups. From CPB initiation to 24 h after surgery, patients in the sivelestat group received a continuous intravenous infusion of 0.2 mg/kg/h sivelestat, whereas patients in the control group received the same volume of 0.9% saline. Blood samples were collected, and levels of interleukin (IL)-6, IL-8, tumor necrosis factor alpha, polymorphonuclear elastase (PMN-E), C-reactive protein (CRP), as well as the white blood cell (WBC) count, platelet count, and neutrophil count (NC) were measured. PMN-E levels, IL-8 levels, WBC count, NC, and CRP levels were significantly lower, and platelet count was significantly higher in the sivelestat group, according to repeated two-way analysis of variance. The activated coagulation time was significantly shorter in the sivelestat group, similarly, blood loss was significantly less in the sivelestat group. In conclusion, Sivelestat attenuates perioperative inflammatory response and clinical outcomes in patients undergoing pediatric heart surgery with CPB.
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http://dx.doi.org/10.1111/aor.12103DOI Listing
December 2013

Novel GPR119 agonist AS1669058 potentiates insulin secretion from rat islets and has potent anti-diabetic effects in ICR and diabetic db/db mice.

Life Sci 2013 Feb 13;92(2):167-73. Epub 2012 Dec 13.

Drug Discovery Research, Astellas Pharma Inc., 21, Miyukigaoka, Tsukuba, Ibaraki, 305-8585, Japan.

Aims: G-protein-coupled receptor 119 (GPR119), mainly expressed in pancreatic β-cells, represents a new target for treating type 2 diabetes. GPR119 agonist is known to induce insulin secretion in a glucose-dependent manner by elevating intracellular cAMP concentrations. This study mainly examined the anti-hyperglycemic effect of a novel candidate small-molecule GPR119 agonist AS1669058 2-(4-bromo-2,5-difluorophenyl)-6-methyl-N-[2-(1-oxidopyridin-3-yl)ethyl]pyrimidin-4-amine ethanedioate on ICR mice and diabetic db/db mice.

Main Methods: We measured blood glucose, plasma insulin, and insulin content in the pancreas after repeated administration of AS1669058 to db/db mice twice daily for one week.

Key Findings: Under high-concentration glucose conditions, AS1669058 induced insulin secretion in a dose-dependent manner in the hamster pancreatic β-cell line HIT-T15 and in rat pancreatic islets. In addition, AS1669058 increased human insulin promoter activity in NIT-1 cells. In in vivo studies, a single administration of AS1669058 (1 mg/kg) in ICR mice improved oral glucose tolerance based on insulin secretion. Further, 1-week repeated treatment (3 mg/kg, twice daily) in diabetic db/db mice significantly reduced blood glucose levels and tended to increase insulin content in the pancreas.

Significance: These results suggest that AS1669058 has promising potential as an extremely more effective anti-hyperglycemic agent than other compounds we previously reported as GPR119 agonists.
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http://dx.doi.org/10.1016/j.lfs.2012.11.015DOI Listing
February 2013

Novel GPR119 agonist AS1535907 contributes to first-phase insulin secretion in rat perfused pancreas and diabetic db/db mice.

Biochem Biophys Res Commun 2010 Nov 16;402(2):280-5. Epub 2010 Oct 16.

Drug Discovery Research, Astellas Pharma Inc., Tsukuba, Ibaraki, Japan.

G protein-coupled receptor (GPR) 119 is highly expressed in pancreatic β-cells and enhances the effect of glucose-stimulated insulin secretion (GSIS) on activation. The development of an oral GPR119 agonist that specifically targets the first phase of GSIS represents a promising strategy for the treatment of type 2 diabetes. In the present study, we evaluated the therapeutic potential of a novel small molecule GPR119 agonist, AS1535907, which was modified from the previously identified 2,4,6-tri-substituted pyrimidine core agonist AS1269574. AS1535907 displayed an EC50 value of 4.8 μM in HEK293 cells stably expressing human GPR119 and stimulated insulin secretion in rat islets only under high-glucose (16.8 mM) conditions. In isolated perfused pancreata from normal rats, AS1535907 enhanced the first phase of insulin secretion at 16.8 mM glucose, but had no effect at 2.8mM glucose. In contrast, the sulfonylurea glibenclamide predominantly induced insulin release in the second phase at 16.8 mM glucose and also markedly stimulated insulin secretion at 2.8 mM glucose. In in vivo studies, a single 10 μM administration of AS1535907 to diabetic db/db mice reduced blood glucose levels due to the rapid secretion of insulin secretion following oral glucose loading. These results demonstrate that GPR119 agonist AS1535907 has the ability to stimulate the first phase of GSIS, which is important for preventing the development of postprandial hypoglycemia. In conclusion, the GPR119 agonist AS1535907 induces a more rapid and physiological pattern of insulin release than glibenclamide, and represents a novel strategy for the treatment of type 2 diabetes.
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http://dx.doi.org/10.1016/j.bbrc.2010.10.015DOI Listing
November 2010

AS1907417, a novel GPR119 agonist, as an insulinotropic and β-cell preservative agent for the treatment of type 2 diabetes.

Biochem Biophys Res Commun 2010 Oct 15;400(4):745-51. Epub 2010 Sep 15.

Drug Discovery Research, Astellas Pharma Inc., Tsukuba, Ibaraki 305-8585, Japan.

G-protein-coupled receptor (GPR) 119 is involved in glucose-stimulated insulin secretion (GSIS) and represents a promising target for the treatment of type 2 diabetes as it is highly expressed in pancreatic β-cells. Although a number of oral GPR119 agonists have been developed, their inability to adequately directly preserve β-cell function limits their effectiveness. Here, we evaluated the therapeutic potential of a novel small-molecule GPR119 agonist, AS1907417, which represents a modified form of a 2,4,6-tri-substituted pyrimidine core agonist, AS1269574, we previously identified. The exposure of HEK293 cells expressing human GPR119, NIT-1 cells expressing human insulin promoter, and the pancreatic β-cell line MIN-6-B1 to AS1907417, enhanced intracellular cAMP, GSIS, and human insulin promoter activity, respectively. In in vivo experiments involving fasted normal mice, a single dose of AS1907417 improved glucose tolerance, but did not affect plasma glucose or insulin levels. Twice-daily doses of AS1907417 for 4weeks in diabetic db/db, aged db/db mice, ob/ob mice, and Zucker diabetic fatty rats reduced hemoglobin A1c levels by 1.6%, 0.8%, 1.5%, and 0.9%, respectively. In db/db mice, AS1907417 improved plasma glucose, plasma insulin, pancreatic insulin content, lipid profiles, and increased pancreatic insulin and pancreatic and duodenal homeobox 1 (PDX-1) mRNA levels. These data demonstrate that novel GPR119 agonist AS1907417 not only effectively controls glucose levels, but also preserves pancreatic β-cell function. We therefore propose that AS1907417 represents a new type of antihyperglycemic agent with promising potential for the effective treatment of type 2 diabetes.
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http://dx.doi.org/10.1016/j.bbrc.2010.08.141DOI Listing
October 2010

Molecular cloning and chromosomal localization of the Bombyx Sex-lethal gene.

Genome 2006 Mar;49(3):263-8

Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.

We cloned Bm-Sxl, an orthologue of the Drosophila melanogaster Sex-lethal (Sxl) gene from embryos of Bombyx mori. The full-length cDNAs were of 2 sizes, 1528 and 1339 bp, and were named Bm-Sxl-L and Bm-Sxl-S, respectively. Bm-Sxl-L consists of 8 exons and spans more than 20 kb of genomic DNA. The open reading frame (ORF) codes for a protein 336 amino acids in length. Bm-Sxl-S is a splice variant that lacks the second exon. This creates a new translation start 138 nucleotides downstream and an ORF that codes for 46 amino acids fewer at the N-terminus. Linkage analysis using an F2 panel mapped Bm-Sxl to linkage group 16 at 69.8 cM. We isolated 2 BACs that include the Bm-Sxl gene. With BAC-FISH we located Bm-Sxl cytogenetically on the chromosome corresponding to linkage group 16 (LG16) at position >68.8 cM.
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http://dx.doi.org/10.1139/g05-108DOI Listing
March 2006

[Grouping of abnormal sexual development--guide to diagnosis].

Authors:
Hiroyuki Oshima

Nihon Rinsho 2004 Feb;62(2):293-9

Tokyo Medical and Dental University, Tateyama Hospital.

Sexual differentiation and development is a process from the moment of fertilization of a ovum by a spermatozoon to achievement of reproductive ability as a male or female. The process includes three steps; establishment of sex chromosome composition, gonadal differentiation and development, and acquirement of phenotypic expression by gonadal hormones. Therefore, abnormal sexual development is divided into three categories according to the above three steps. In humans, however, gender is assigned at birth. Then, individuals grow under social environment provided according to the gender assigned and acquire gender role during childhood and gender identity during puberty. As observed in those with trans-sexualism, it appears likely that gender identity plays a major role on sexual behavior of humans.
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February 2004

Significant association of Rho/ROCK pathway with invasion and metastasis of bladder cancer.

Clin Cancer Res 2003 Jul;9(7):2632-41

Department of Urology, Dokkyo University School of Medicine, Tochigi 321-0293, Japan.

Purpose: The small GTP-binding protein Rho and its best-characterized downstream effector Rho-associated serine-threonine protein kinase, ROCK, participate in actin cytoskeleton organization, and are linked to pathogenesis and progression of several human tumors. We investigated the roles of Rho and ROCK in bladder cancer.

Experimental Design: Using Western blotting, we quantitated Rho and ROCK protein expression in paired tumor and nontumor surgical samples from 107 consecutive Japanese patients with bladder cancer.

Results: RhoA, RhoC, and ROCK were more abundant in tumors and metastatic lymph nodes than in nontumor bladder and uninvolved lymph nodes (P < 0.0001). Amounts of RhoA and RhoC protein, and ROCK protein expression correlated positively with one another (P < 0.0001). High RhoA, RhoC, and ROCK expression were related to poor tumor differentiation (P < 0.05, P < 0.01, and P < 0.01, respectively), muscle invasion (P < 0.001), and lymph node metastasis (P < 0.05). Kaplan-Meier plots linked high RhoA, RhoC, and ROCK protein expression to shortened disease-free and overall survival (P < 0.0001). By univariate analysis, high RhoA, RhoC, and ROCK protein expression predicted shortened disease-free and overall survival (P < 0.0001). By multivariate analysis, only RhoC was independently influenced in disease-free survival (P < 0.05), and RhoA and RhoC in overall survival (P < 0.001). In contrast, RhoB expression was inversely related to the grade and stage (P < 0.05), and its higher expression is associated with better overall survival (P < 0.05). In superficial tumors (Ta or T1; 63 patients), RhoA, RhoC, and ROCK were unrelated with recurrence-free survival. Overall survival in tumors invading muscle (T2 to T4; 44 patients) was significantly influenced by RhoA, RhoC, and ROCK in a Kaplan-Meier analysis (P < 0.0001, P < 0.0001, and P < 0.01, respectively). Whereas RhoA, RhoC, and ROCK independently predicted shortened overall survival in patients with invasive tumor by univariate analysis (P < 0.0001, P < 0.0001, and P < 0.01, respectively), only RhoC did so by multivariate analysis (P < 0.05).

Conclusion: Rho/ROCK pathway apparently involved in occurrence and progression of bladder cancer may be valuable prognostic markers.
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July 2003

Molecular cloning of a putative gastric chitinase in the toad Bufo japonicus.

Zoolog Sci 2002 Mar;19(3):293-7

Department of Biology, School of Education, Waseda University, Tokyo, Japan.

On the basis of our preliminary observation that a crude extract of the stomach of the toad Bufo japonicus exhibited a chitinase activity with its optimum pH around 3.0, we undertook molecular cloning of a cDNA encoding this putative gastric chitinase. By use of 2 degenerate oligonucleotide primers derived from the 2 conserved regions of the vertebrate chitinases, a reverse transcription-PCR product was obtained. This product was used as a probe to screen a cDNA library constructed from the toad stomach. The longest positive clone was revealed to contain an open reading frame for a putative chitinase protein of 484 amino acids, which protein exhibited sequence similarity to the known vertebrate chitinases. Our data also revealed this putative gastric chitinase to be distinct from the chitinase that we had previously isolated from the pancreas of the same species. In this putative gastric chitinase, both the N-terminal catalytic domain and the C-terminal chitin-binding domain were perfectly conserved, suggesting this protein to function as chitinase in the toad stomach.
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http://dx.doi.org/10.2108/zsj.19.293DOI Listing
March 2002

Isolation and sequence of a novel amphibian pancreatic chitinase.

Comp Biochem Physiol B Biochem Mol Biol 2002 Jun;132(2):381-8

Department of Biology, School of Education, Waseda University, Nishi-waseda 1-6-1, Shinjuku-ku, Tokyo 169-8050, Japan.

An approximately 60-kDa protein with chitinase activity was purified from the pancreas of the toad Bufo japonicus. Its specific activity was 4.5 times higher than that of a commercial bacterial chitinase in fragmenting crab shell chitin, and its optimal pH was approximately 6.0. A cDNA clone encoding a protein consisting of 488 amino acid residues, including part of the peptide sequence determined from the isolated protein, was obtained from a toad pancreas cDNA library. The deduced amino acid sequence indicated that the protein contained regions with high homology to those present in chitinases from different species, with the amino acid residues for the chitinase activity and the chitin-binding ability being completely conserved. We designate the protein as toad pancreatic chitinase (tPCase). Northern blot analysis revealed the mRNA of this enzyme to be expressed exclusively in the pancreas. Toad PCase is the first amphibian chitinase to be identified as well as the first pancreatic chitinase identified in a vertebrate.
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http://dx.doi.org/10.1016/s1096-4959(02)00046-5DOI Listing
June 2002
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