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Yoshida M.,Japan National Institute of Health Sciences | Katsuda S.-I.,Japan Food Research Laboratories | Maekawa A.,Tokyo Institute of Technology
Journal of Toxicologic Pathology | Year: 2012

Involvements of estrogen receptor (ER)α, proliferating cell nuclear antigen (PCNA) and p53 in the uterine carcinogenesis process in Donryu rats, a high yield strain of the uterine cancer were investigated immunohistochemically. ERα was expressed in atypical endometrial hyperplasia, accepted as a precancerous lesion of the uterine tumors, as well as well- and in moderately-differentiated endometrial adenocarcinomas, and the intensities of expression were similar to those in the luminal epithelial cells of the atrophic uterus at 15 months of age. The expression, however, was negative in the tumor cells of poorly differentiated type. Good growth of implanted grafts of the poorly-differentiated adenocarcinomas in both sexes with or without gonadectomy supported the estrogen independency of tumor progression to malignancy. PCNA labeling indices were increased with tumor development from atypical hyperplasia to adenocarcinoma. The tumor cells in poorly-differentiated adenocarcinomas were positive for p53 positive but negative for p21 expression, suggesting accumulation of mutated p53. These results indicate that the consistent ERα expression is involved in initiation and promotion steps of uterine carcinogenesis, but not progression. In addition, PCNA is related to tumor development and the expression of mutated p53 might be a late event during endometrial carcinogenesis. © 2012 The Japanese Society of Toxicologic Pathology. Source

Chihara M.,Hokkaido University | Nakamura T.,Hokkaido University | Nakamura T.,Section of Biological Safety Research | Sakakibara N.,Japan Food Research Laboratories | And 3 more authors.
American Journal of Pathology | Year: 2014

Spermatocytes of MRL/MpJ mice are more heat resistant than those of C57BL/6 mice in experimental cryptorchidism. This phenotype depends in part on the locus at the 81-cM region of MRL/MpJ-type chromosome 1 (Chr 1). To evaluate the function of this locus, we examined pathological changes in mouse testes resulting from transient scrotal heat stress. Immediately after scrotal heat stress, meiosis progression and blood-testis barrier integrity were preserved in MRL/MpJ but not in C57BL/6 mice, nor in a C57BL/6-based congenic strain carrying the MRL/MpJ-derived Chr 1 locus (B6.MRLc1). Testicular damage was severe in the weeks after scrotal heat stress in all three strains; however, testicular calcification was observed only in C57BL/6 and MRL/MpJ mice (initially as nanocrystals in mitochondria of degenerating germ cells). In testes, expression of gremlin 2, a bone morphogenetic protein antagonist encoded on Chr 1, was markedly higher in B6.MRLc1 than in C57BL/6 or MRL/MpJ mice. Furthermore, gremlin-2 and bone morphogenetic protein 2 mRNA levels in heated testes correlated negatively and positively, respectively, with calcification. Thus, although the MRL/MpJ-derived locus on Chr 1 may play a pivotal role in recovery from heat-induced testicular damage, especially via inhibition of calcification, MRL/MpJ mice have a precipitating factor for testicular calcification and heat shock-resistant factors that reside outside the 81-cM region of Chr 1. © 2014 American Society for Investigative Pathology. Source

Uchida H.,Agilent Technologies | Taira Y.,Okinawa Institute of Science and Technology | Yasumoto T.,Japan Food Research Laboratories
Rapid Communications in Mass Spectrometry | Year: 2013

RATIONALE The ovatoxins are palytoxin analogs of a dinoflagellate origin implicated in human intoxication. The structures of ovatoxin-A, ovatoxin-d, and ovatoxin-e produced by the IK2 strain of Ostreopsis ovata collected in Japan were elucidated using liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOFMS). The novel structures and a new insight into the spectral data are presented. METHODS The structural elucidations were carried out by complementary use of positive and negative ion LC/QTOFMS. Ostreocin-D (C127H219N3O53), another palytoxin congener previously elucidated by negative fast-Atom bombardment collision-induced tandem mass spectrometry (FAB CID MS/MS), was used as a reference. RESULTS Positive ion spectra allowed deduction of hydroxyl positions based on the conjugated polyene structures produced, while the negative ion spectra allowed assignments of cleavage sites of C-C bonds. The analysis could be performed using a small sample without extensive purification. CONCLUSIONS Ovatoxin-A IK2 (C129H223N3O52), ovatoxin-d IK2 (C129H223N3O53), and ovatoxin-e IK2 (C129H223N3O53) were tentatively assigned to 42-hydroxy-17,44,70-trideoxypalytoxin, 42-hydroxy-17,70-dideoxypalytoxin and 42,82-dihydroxy-17,44,70- trideoxypalytoxin, respectively. The wide applicability of the method was suggested. Copyright © 2013 John Wiley & Sons, Ltd. Source

Yogi K.,Okinawa Institute of Science and Technology | Yogi K.,Okinawa Prefectural Institute of Health and Environment | Oshiro N.,Okinawa Prefectural Institute of Health and Environment | Inafuku Y.,Okinawa Prefectural Institute of Health and Environment | And 2 more authors.
Analytical Chemistry | Year: 2011

Toxin profiles of representative ciguatera species caught at different locations of Japan were investigated in fish flesh by high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. Identification and quantification of 16 toxins were facilitated by the use of 14 reference toxins prepared by either synthesis or isolation from natural sources and the previous LC-MS data thereof. Sodium adduct ions [M + Na] + were used as parent and product ions. Distinct regional differences were unveiled: ciguatoxin-1B type toxins were found in snappers and groupers from Okinawa, ciguatoxin-3C type toxins were found in a spotted knifejaw, Oplegnathus punctatus, from Miyazaki located 730 km north of Okinawa, and both types of toxins were found in a red snapper, Lutjanus bohar, from Minamitorishima (Marcus) Island. Twelve toxins were identified in a dinoflagellate, Gambierdiscus toxicus, collected as the primary toxin source in French Polynesia. Occurrence of M-seco-toxins in fish and oxidized toxins in the dinoflagellate was confirmed for the first time. The present LC-MS/MS method is rapid, specific, and accurate. It not only outperforms the currently employed mouse bioassays but also enables the study of the toxin dynamics during the food chain transmission. © 2011 American Chemical Society. Source

Yamazaki K.,Japan Food Research Laboratories | Isagawa S.,Japan Food Research Laboratories | Kibune N.,Japan Food Research Laboratories | Urushiyama T.,Chiyoda Corporation
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2012

A novel GC-MS method was developed for the determination of acrylamide, which is applicable to a variety of processed foods, including potato snacks, corn snacks, biscuits, instant noodles, coffee, soy sauces and miso (fermented soy bean paste). The method involves the derivatization of acrylamide with xanthydrol instead of a bromine compound. Isotopically labelled acrylamide (d3-acrylamide) was used as the internal standard. The aqueous extract from samples was purified using Sep-Pak™ C18 and Sep-Pak™ AC-2 columns. For amino acid-rich samples, such as miso or soy sauce, an Extrelut™ column was used for purification or extraction. After reaction with xanthydrol, the resultant N-xanthyl acrylamide was determined by GC-MS. The method was validated for various food matrices and showed good linearity, precision and trueness. The limit of detection and limit of quantification ranged 0.5-5 and 5-20 μg kg-1, respectively. The developed method was applied as an exploratory survey of acrylamide in Japanese foods and the method was shown to be applicable for all samples tested. © 2012 Copyright Taylor and Francis Group, LLC. Source

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