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Biomedical subjects

Y Umesaki

Publications and source records attributed to Y Umesaki.

30 records · Page 2Linked to original sources
PubMed1992

Immune responses of mice to orally administered asialo GM1-specific rabbit IgG in the presence or absence of cholera toxin.

Cholera toxin (CT) has been shown to be a most potent mucosal immunogen and an adjuvant to orally administered unrelated antigens. We investigated the effect of the oral administration of substances with the ability to bind to intestinal epithelial cells on the immune responses against themselves in the presence or absence of CT. Mice were fed non-specific rabbit IgG (RGG) or rabbit IgG (a-GA1) specific to asialo GM1 glycolipid, a major component of the apical membrane of mouse small intestinal epithelial cells, with or without CT. Oral administration of a-GA1 evoked stronger antibody responses than that of RGG in both the serum and intestinal fluid in the presence of CT. However, when the antigens were administered singly without CT, no significant antibody response was detected. In this case, oral administration of RGG induced severe suppression of the systemic antibody response to a subsequent intraperitoneal injection of RGG. In contrast, a-GA1 could not induce oral tolerance. Together these findings suggest that substances with the ability to bind to intestinal epithelial cells are strong immunogens in the presence of CT and weak tolerogens in the absence of CT.

Adjuvants, Immunologic↗
PubMed1989

Structural and compositional difference in the neutral glycolipids between epithelial and non-epithelial tissue of the mouse small intestine.

Five major neutral glycolipids, GL-1-GL-5, were isolated from the mouse small intestine. Their structures and distribution were determined by permethylation analysis, sequential degradation with exoglycosidases and/or immunohistochemistry. The molar ratio of GL-1, GL-2, GL-3, GL-4 and Gl-5 in the whole small intestine was 1:0.04:0.03:0.42:0.02. The structures of GL-1 and GL-4 present in epithelial cells were reported previously to be glucosyl ceramide and asialo GM1, respectively (Umesaki, Y., Suzuki, A., Kasama, T., Tohyama, K., Mutai, M. and Yamakawa, T. (1981) J. Biochem. 90, 1731-1738). GL-5, also present in the epithelial cells, was fucosyl asialo GM1, and fucose was shown to be linked to terminal galactose of asialo GM1 in the manner of alpha(1-2) bond. GL-2 and GL-3, present in the residual tissue after scraping the mucosa, were determined to be globoside and Forssman glycolipid, respectively. Both globoside and Forssman glycolipid of the non-epithelial tissue had non-hydroxy fatty acid (C16-C24) in combination with sphingosine (C18) as the ceramide components, in contrast with the ceramide structures of the epithelial glycolipids, which contained alpha-hydroxy fatty acids in combination with phytosphingosine. Immunohistochemical staining using anti-glycolipid antibodies confirmed the distribution of asialo GM1 and fucosyl asialo GM1, and Forssman glycolipid in the epithelial and non-epithelial tissue, respectively.

Animals↗
PubMed1989

Factors regulating the expression of the neutral glycolipids in the mouse small intestinal mucosa.

GDP-fucose:asialo GM1 alpha(1-2)fucosyltransferase (FT) is induced in the small intestinal mucosa after microbial contamination of germ-free mice (Umesaki, Y., Sakata, T. and Yajima, T. (1982) Biochem. Biophys. Res. Commun. 105, 439-443). As a result, asialo GM1 glycolipid, a major component of the epithelial cell membrane, drastically converted into fucosyl asialo GM1. There were many other examples in which FT was induced. One was the weaning period for conventional mice. Others included injuries of the small intestine by punctures or administration of cytosine arabinoside, and the injection of protein synthesis inhibitors, such as cycloheximide or emetine, or the soluble fraction of the small intestinal homogenate (SISF). The induction of FT was more rapid after injection of cycloheximide or SISF than after injury, mechanical puncturing or after administration of cytosine arabinoside. The changes in the neutral glycolipids of the small intestine by injection of cycloheximide or SISF were analyzed in detail. FT activity started to increase after approx. 5 h and reached the maximum 10-12 h after injection of cycloheximide or SISF, and rapidly declined thereafter. The conversion of asialo GM1 into fucosyl asialo GM1 started after about 10 h and reached the maximal value 24 h after the treatment. Fucosyl asialo GM1 persisted for a few days, although the FT activity fell to near the basal level. On the other hand, the amount of glucosyl ceramide was constant after these treatments. There was little difference in the time-courses of both the FT activity and the glycolipid conversion between these treatments. In the case of co-injection of cycloheximide and SISF, the effect of both materials on FT activity induction was synergistic. The distribution of FT activity and immunohistochemical staining using anti-fucosyl asialo GM1 antibody along the crypt-villus axis showed a stronger expression of fucosyl asialo GM1 in villus portion, the post-mitotic cell zone, than in the crypt portion. Asialo GM1 was converted into fucosyl asialo GM1 after the induction of FT by the various treatments mentioned above. Especially the effects of cycloheximide and/or SISF on FT induction suggest at least the presence of a regulatory protein(s) which controls the glycolipid expression in the small intestine.

Animals↗
PubMed1984

Immunohistochemical and biochemical demonstration of the change in glycolipid composition of the intestinal epithelial cell surface in mice in relation to epithelial cell differentiation and bacterial association.

We have previously demonstrated the appearance of fucosyl asialo-GM1 (FGA1) in the small-intestinal epithelial cells of germ-free mice via the induction of GDP-fucose: asialo-GM1 (GA1) alpha(1 leads to 2) fucosyltransferase (FT) after the conventionalization of these animals (Umesaki Y, Sakata T, Yajima T: Biochem Biophys Res Commun 105:439, 1982). The present study, based on this earlier work, demonstrates the changes in the glycolipid antigens of the small-intestinal epithelial-cell membrane as shown immunohistochemically with specific antibodies raised against asialo GM1 (GA1) and FGA1. In germ-free mice, GA1 was localized both in the villus cells and in the crypt cells. In the process of conventionalization, FGA1 appeared in the villus cells while the GA1 content of these cells was decreased. Four to 5 days after the conventionalization procedure, the fluorescence produced by anti-FGA1 was strongest in the villus cells, while that produced by anti-GA1 was detected only in the crypt cells. At this same time the FT activity of the small-intestinal mucosa was highest, with most of the GA1 apparently being converted into FGA1, as shown in the paper cited above. Thereafter, the GA1 content of both the villus and crypt cells again increased greatly. On the other hand, the fluorescence produced with anti-FGA1 decreased, and could no longer be detected 14 days after conventionalization. The activity of FT, measured biochemically in epithelial cells differentially isolated from the villus tip to the crypt, was greater in the villus than in the crypt region. This confirmed the intense staining with anti-FGA1 that was seen in villus cells. The fluorescence produced by the two anti-glycolipid antibodies used in the study distributed not only in the microvillus membrane but also to some extent in the basolateral membrane. The localization of the respective glycolipids contrasted with that of the glycoprotein sucrase--isomaltase enzyme complex, the fluorescence of which was exclusively confined to the microvillus-membrane side of the villus cells.

Animals↗
PubMed1982

Biosynthesis of microvillus membrane-associated glycoproteins of small intestinal epithelial cells in germ-free and conventionalized mice.

We studied the effect of intestinal microorganisms on the synthesis of membrane-associated glycoproteins in the upper small intestine by intraperitoneally administering L-[3H]fucose, D-[14C]glucosamine, or L-[3H]leucine to germ-free mice and mice exposed to microorganisms for 4 weeks (conventionalized). The incorporation of the labeled compounds into sucrase-isomaltase complex and maltase was determined by immunoprecipitating Triton X-100-solubilized microvillus membranes with their antibodies. Purified microvillus membranes from germ-free and conventionalized mice differed in the activities of some marker enzymes but not in the number and mobility of the components on SDS-polyacrylamide gel electrophoresis. Maximal incorporation of [3H]fucose and [14C]glucosamine into the microvillus membrane and two enzymes was reached 2-3 h post-injection in both groups, however, the amounts incorporated were larger in conventionalized mice. There was little difference in [3H]leucine incorporation into the total glycoproteins of microvillus membranes between the two groups. Our results suggest that the introduction of microorganisms stimulates the synthesis of sugar chains of microvillus membrane-associated glycoproteins. The enhanced in vitro fucosyltransferase activity in conventionalized mice partly supports this suggestion.

Animals↗
PubMed1981

Appearance of fucolipid after conventionalization of germ-free mice.

Incorporation of [6-3H]fucose and [1-14C]glucosamine into the lipid fraction of microvillus membrane (MVM) was studied in germ-free and conventionalized mice after intraperitoneal injection of the radioactive precursors. Incorporation of [6-3H]fucose was clearly detected in conventionalized mice but not detectable in germ-free mice. There was no difference in the incorporation of [1-14C]glucosamine between the two groups. The lipid fraction of MVM labeled with [6-3H]fucose showed a spot of slower mobility than asialo GM1 on TLC with autoradiography and it was confirmed to be a fucolipid on abolishing the radiolabeled original spot by alpha-L-fucosidase treatment. These results suggest that the synthesis of the fucolipid is induced by conventionalization of germ-free mice.

Animals↗
PubMed1981

Presence of asialo GM1 and glucosylceramide in the intestinal mucosa of mice and induction of fucosyl asialo GM1 by conventionalization of germ-free mice.

Two major neutral glycolipids of the intestinal mucosa were purified by a series of column chromatographies and the structures were determined to be glucosylceramide and asialo GM1 by gas liquid chromatography. The carbohydrate structure of asialo GM1 was also confirmed from the reactivity of the glycolipid to rabbit anti-asialo GM1 antibody by an enzyme linked-immunosorbent antibody. The ceramide portion of both glycolipids had an extremely hydrophilic nature and more than 90% of the ceramide was composed of phytosphingosine and alpha-hydroxy fatty acids. In the previous paper we reported that the induction of a fucolipid in the microvillus membrane of mouse intestinal mucosa by conventionalization was observed on monitoring the incorporation of radiolabeled fucose in vivo. A fucoglycolipid having the same mobility on an autoradiogram as the fucolipid labeled in vivo was produced by in vitro incubation of intestinal asialo GM1 and GDP-[14C]fucose with the mucosal homogenates. Moreover, asialo GM1 prepared from brain gangliosides exhibited a similar ability to accept fucose and it was converted to fucosyl asialo GM1 which moved faster than the product from intestinal asialo GM1. The difference is considered to be due to the ceramide composition. These results suggest that conventionalization can induce the fucosyl asialo GM1 in the microvillus membrane probably through the induction of fucosyltransferase. Understanding the molecular mechanism of interaction between the physiological flora and host is the matter of further study.

Animals↗
PubMed1980

Characterization of acetate uptake by the colonic epithelial cells of the rat.

The characteristics of acetate uptake by colonic epithelial cells of the rat were studied. Clear saturation kinetics of acetate uptake were not observed in these experiments at either 0 degrees C or 30 degrees C. A decrease in the pH of the medium markedly increased the acetate uptake. The activation energy for acetate uptake derived from an Arrhenius plot was about 6.1 kcal/mole. Among the inhibitors tested, no effective inhibition of acetate uptake at 0 degrees C was observed. Metabolic inhibitors severely inhibited transport at 30 degrees C. Inhibition of acetate uptake by other short chain fatty acids, which was non-competitive, was observed. The finding that efflux from the cells was stimulated in the presence of compounds such as pyruvate and bicarbonate supported the notion of a close interrelationship between weak electrolyte transports in vivo. Although the H+ gradient across the cell membrane is suggested to be one of the factors determining the uptake rate, it seems difficult to explain all the results in this way.

Absorption↗
PubMed1979

Effect of organic acid absorption on bicarbonate transport in rat colon.

The absorption of organic anions and the influence of these anions on the movement of HCO3- were studied in vivo in rat colon using a perfusion technique. The absorption of short chain fatty acids (SCFA's) such as acetate, propionate, and butyrate was much greater than that of succinate or lactate. With increasing initial concentration of SCFA up to 100 mmol . 1-1, SCFA absorption increased linearly in correspondence with HCO3- appearance. Final pCO2 level of the perfusion solution with SCFA was the same as the plasma level. Among the SCFA's, no significant differences in absorption or their effects on HCO3- appearance were observed. The presence of Na+ stimulated SCFA absorption, and the maximum value was obtained at more than 100 mmol . 1-1 of Na+. These results suggest that a specific system for HCO3- secretion activated by SCFA exists in the colon, and that this system may control the intraluminal pH by the alkalization of intestinal contents.

Acetates↗
PubMed1977

Effect of Tween 80 on glucosyltransferase production in Streptococcus mutans.

Glucan production from sucrose by Streptococcus mutans OMZ 176 was stimulated approximately threefold in the presence of 0.1% Tween 80. When OMZ 176 was grown in a medium containing glucose, the glucosyltransferase level in the medium was also increased about fivefold in the presence of 0.1% Tween 80. The glucosyltransferase level increased in proportion to the logarithm of the concentration of Tween 80 in the glucose medium. Tween 80 affected neither bacterial growth nor the activity of glucosyltransferase. The appearance of glucosyltransferase in the glucose medium was inhibited immediately by chloramphenicol and actinomycin D and, after a lag, by rifampin as well. It was observed that the fatty acid composition of the cells grown with Tween 80 was altered. These results suggest that Tween 80 stimulates glucosyltransferase synthesis either directly, or indirectly by promoting glucosyltransferase secretion.

Chloramphenicol↗