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H Setoyama

Publications and source records attributed to H Setoyama.

At least 19 recordsLinked to original sources
PubMed2005

Photoionization of small krypton clusters in the Kr 3d regime: evidence for site-specific photoemission.

Kr 3d ionization energies of small, variable size krypton clusters are investigated by photoelectron spectroscopy, where the size regime of clusters with an average size N< or =30 is studied. Characteristic shifts in Kr 3d ionization energies to lower binding energies are found compared to the bare atom. These are also different from those of large krypton clusters. Moreover, we find evidence for photoionization of the krypton dimer. Its 3d ionization energy is barely shifted relative to the atomic value. Results from model calculations considering different isomers and cluster sizes as well as defect sites give evidence that the experimental results can be related to photoionization from different surface sites in variable size krypton clusters. This can be related to site-specific photoemission in small Kr clusters. The results are compared to size effects in Kr 3d near-edge features of variable size Kr clusters as well as recent results on Kr 3d photoionization of large Kr clusters.

Journal Article↗
PubMed2004

Improvement of human faecal flora-associated mouse model for evaluation of the functional foods.

AIMS: Animal models are required for evaluation of the functional foods such as pro/prebiotics exerting effects through the metabolism of the intestinal microflora. The object of this study was to establish new human flora-associated mice reflecting the environment of the human intestinal tract. METHODS AND RESULTS: We inoculated a human faecal suspension into segmented filamentous bacteria (SFB) monoassociated mice as a model system. In both human flora (HF) and SFB-associated mouse (HF-SFB mouse), intestinal characteristics such as the composition of intraepithelial lymphocytes, the expression of major histocompatibility complex (MHC) class II molecules and the number of immunoglobulin A-producing cells in the mucosa was closer to those of conventionally reared mice than was case with human flora-associated mice (HF mice) lacking SFB. Several predominant bacterial groups except lactobacilli in human flora were found in faeces of HF-SFB mice. Lactobacilli established small populations in the gut of HF-SFB mice when administered before inoculation with the human flora. Faecal enzymatic activities and organic acid concentration of HF-SFB mice proportionally reflected those of the donor subject. CONCLUSION: We established a new human flora-associated mouse (HF-SFB mouse), in which intestinal characteristics are normally developed and their major microbial composition reflect the human. SIGNIFICANCE AND IMPACT OF THE STUDY: HF-SFB mice are a valuable model for studying pro/prebiotic effects on the human intestine.

Acetates↗
PubMed2000

Structure of the intestinal flora responsible for development of the gut immune system in a rodent model.

The intestinal flora comprising indigenous, autochthonous bacteria is constantly present in the alimentary tract of host animals, including humans. The indigenous bacteria greatly affect the structure and functions of the intestinal mucosa. Studies involving gnotobiotic mice or rats have shown that the presence of limited kinds of intestinal bacteria is responsible for the development of the gut immune system, such as secretory IgA, major histocompatibility complex molecules and intraepithelial lymphocytes. Understanding of the structure of the intestinal flora or the organization of the microbial population in the intestine, based on evaluation of the immunological responses, may clarify its functions in the host animal.

Animals↗
PubMed1999

Differential roles of segmented filamentous bacteria and clostridia in development of the intestinal immune system.

The presence of microflora in the digestive tract promotes the development of the intestinal immune system. In this study, to evaluate the roles of two types of indigenous microbe, segmented filamentous bacteria (SFB) and clostridia, whose habitats are the small and large intestines, respectively, in this immunological development, we analyzed three kinds of gnotobiotic mice contaminated with SFB, clostridia, and both SFB and clostridia, respectively, in comparison with germfree (GF) or conventionalized (Cvd) mice associated with specific-pathogen-free flora. In the small intestine, the number of alpha beta T-cell receptor-bearing intraepithelial lymphocytes (alpha betaIEL) increased in SFB-associated mice (SFB-mice) but not in clostridium-associated mice (Clost-mice). There was no great difference in Vbeta usage among GF mice, Cvd mice, and these gnotobiotic mice, although the association with SFB decreased the proportion of Vbeta6(+) cells in CD8beta- subsets to some extent, compared to that in GF mice. The expression of major histocompatibility complex class II molecules on the epithelial cells was observed in SFB-mice but not in Clost-mice. On the other hand, in the large intestine, the ratio of the number of CD4(-) CD8(+) cells to that of CD4(+) CD8(-) cells in alpha betaIEL increased in Clost-mice but not in SFB-mice. On association with both SFB and clostridia, the numbers and phenotypes of IEL in the small and large intestines changed to become similar to those in Cvd mice. In particular, the ratio of the number of CD8alpha beta+ cells to that of CD8alpha alpha+ cells in alpha betaIEL, unusually elevated in the small intestines of SFB-mice, decreased to the level in Cvd mice on contamination with both SFB and clostridia. The number of immunoglobulin A (IgA)-producing cells in the lamina propria was more elevated in SFB-mice than in Clost-mice, not only in the ileum but also in the colon. The number of IgA-producing cells in the colons of Clost-mice was a little increased compared to that in GF mice. Taken together, SFB and clostridia promoted the development of both IEL and IgA-producing cells in the small intestine and that of only IEL in the large intestine, respectively, suggesting the occurrence of compartmentalization of the immunological responses to the indigenous bacteria between the small and large intestines.

Animals↗
PubMed1998

Inflammatory bowel disease-like enteritis and caecitis in a senescence accelerated mouse P1/Yit strain.

BACKGROUND: A new subline of the senescence accelerated mouse (SAM) P1/Yit strain has been established which shows spontaneous enteric inflammation under specific pathogen free (SPF) conditions. AIMS: To elucidate the pathogenesis of enteric inflammation in this new subline. METHODS: The SPF and germ free (GF) SAMP1/Yit strains were used. Histological, immunological, and microbiological characterisation of the mice with enteric inflammation was performed. RESULTS: Histologically, enteritic inflammation developed as a discontinuous lesion in the terminal ileum and caecum with the infiltration of many inflammatory cells after 10 weeks of age. the activity of myeloperoxidase, and both immunolocalisation and mRNA expression of inducible nitric oxide synthase increased in the lesion. CD3-epsilon positive T cells, neutrophils, and macrophages were more numerous in the inflamed mucosa of the SAMP1/Yit strain. The GF SAMP1/Yit strain did not show any inflammation in the intestinal wall, by the age of 30 weeks, and the enteritis and caecitis developed 10 weeks after the conventionalisation of the GF SAMP1/Yit strain. CONCLUSION: Enteric inflammation in the ileum and caecum developed in the SAMP1/Yit strain. The pathophysiological characteristics of the disease in this mouse have some similarities to those of human inflammatory bowel disease (IBD). This mouse strain should be a useful model system for elucidating the interaction between the pathogenesis of IBD and the gut microflora.

Aging↗
PubMed1997

Bi-phasic allometric growth of the small intestine, cecum and the proximal, middle, and distal colon of rats (Rattus norvegicus Berkenhout, 1764) before and after weaning.

We studied whether the growth of the intestinal tract changes at weaning. We weighted fresh tissue and measured segment length of the small intestine, cecum and proximal, middle, and distal colon of 45 male and 51 female F344/Yit rats (Rattus norvegicus Berkenhout, 1764) of 0 to 428 days old. We performed correlation analysis among tissue weight, segment length and empty body weight after logarithmic transformation of the data. The growth of the small and large intestine was biphasic. Intestinal growth exceeded body growth during the suckling period and slowed down suddenly after weaning. Sexual differences existed in intestinal growth, although much smaller than the difference before and after weaning. These results appear to suggest that the size of intestinal tract of the rat does not adapt to nutritional changes at weaning, but prepare for weaning beforehand.

Animals↗
PubMed1996

Proliferative recruitment of intestinal intraepithelial lymphocytes after microbial colonization of germ-free mice.

Intraepithelial lymphocytes (IEL), particularly alpha beta TCR-bearing IEL (alpha beta-IEL), dramatically increase in number after microbial colonization of formerly germ-free (ex-GF) mice (Umesaki et al., Immunology 1993. 79: 32). In this study, the kinetics of expansion of IEL after microbial colonization in ex-GF mice were investigated by the bromodeoxyuridine (BrdUrd) continuous labeling method. In GF mice, gamma delta- and alpha beta-IEL were gradually labeled with BrdUrd, reaching approximately 30% and 15% labeling, respectively, after 10 days of continuous BrdUrd labeling. In conventional (CV) mice, the percentage of BrdUrd-labeled alpha beta-IEL was a little higher than that for gamma delta-IEL. The maximal labeling for alpha beta-IEL and gamma delta-IEL reached 50-60% and 40%, respectively, in 10 days. In the case of conventionalized ex-GF mice, continuous labeling was started 11 days after microbial colonization of GF mice because alpha beta-IEL outnumbered gamma delta-IEL during this period. In this case, 75% of alpha beta-IEL and 67% of gamma delta-IEL were labeled with BrdUrd in 10 days. On the other hand, the apparent half lives of alpha beta-IEL and gamma delta-IEL were 10 and 20 days, respectively in CV mice. These results strongly suggest that the number of IEL, particularly alpha beta-IEL, increases after microbial colonization through recruitment into the cell cycle of a large proportion of IEL or their immediate precursors. The difference in the relative BrdUrd-labeling rate of alpha beta-IEL to that of gamma delta-IEL between germ-free and conventionalized mice indicates a preferential increase in the alpha beta-IEL subset during the course of conventionalization.

Animals↗