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Biomedical subjects

E Kobayashi

Publications and source records attributed to E Kobayashi.

At least 271 records · Page 15Linked to original sources
PubMed1995

Syngeneic small-bowel grafting increases susceptibility to lethal graft-versus-host disease in the rat.

The rat model has been used to present evidence of the effect of surgical damage on the immune system. Syngeneic small bowel transplantation (SBT) has been used to show an increased incidence of graft-versus-host disease (GVHD) as well as thymic atrophy and altered host T cell proliferative response. Syngeneic auxiliary SBT was carried out between (LEW x BN)F1 hybrids. Varying amounts of LEW mesenteric lymphocytes were injected into the last animals to induce GVHD. Results showed that in the SBT recipients the incidence of lethal GVHD was increased when compared with untreated or sham-laparotomy controls. Marked thymic atrophy was also observed, while the number of hepatic lymphocytes increased transiently. Lymphocyte proliferation in response to concanavalin A or interleukin-2 was impaired for up to 21 days postoperatively, whereas the mixed lymphocyte reaction reactivity was not affected. These results show that the number and proliferative activity of thymic T cells were impaired after major small bowel transplantation surgery and that extrathymic lymphocytes were developed in the liver.

Animals↗
PubMed1995

Immunostimulatory and antitumor activities of monoglycosylceramides having various sugar moieties.

Ten kinds of monoglycosylceramides (MonoCers), having the same ceramide portion and different sugar moieties, were synthesized and their immunostimulatory and antitumor activities were examined. The manner of combination between sugar and ceramide has been demonstrated to affect the manifestation of immunostimulatory and resultant antitumor activities of MonoCers, and in the case of D-MonoCers having the D-sugar, alpha-D-MonoCers (sugar combined to ceramide in an alpha-configuration) show stronger activities than beta-D-MonoCers. Furthermore, the form of sugar, not the furanose-form but the pyranose-form, and the 2"- and 4"-hydroxyl groups of the pyranose-form of sugar, seemed to play an important role in the manifestation of the activities of alpha-D-MonoCers.

Adjuvants, Immunologic↗
PubMed1995

Synthesis and antitumor activity of duocarmycin derivatives.

A series of duocarmycin B2 derivatives, modified at the phenolic hydroxyl group to ester, carbonate and carbamate, was synthesized. Antitumor activity of these analogs was preliminarily evaluated by assays of growth inhibition of HeLa S3 cells (in vitro) and antitumor activity against murine sarcoma 180 (in vivo). The stability of the compounds under aqueous conditions was examined, and we found a correlation between antitumor activity in vivo and stability in aqueous solution, that is, the more stable derivatives exhibited higher antitumor activity. Among these derivatives, the N,N-dialkylcarbamoyl analogs exhibited both improved antitumor activity and higher stability compared with duocarmycin B2. These analogs were subjected to further biological evaluation and they expressed broad-spectrum activity toward murine solid tumors M5076, Colon 26 and Colon 38, and human xenografted carcinoma MX-1.

Animals↗
PubMed1995

Continuous and massive intake of chitosan affects mineral and fat-soluble vitamin status in rats fed on a high-fat diet.

We investigated the effects of continuous and massive intake of chitosan with sodium ascorbate (AsN) on the mineral and the fat-soluble vitamin status in male Sprague-Dawley rats fed on a high-fat diet. The apparent fat digestibility in the chitosan-receiving group was significantly lower than that in the cellulose- or glucosamine-receiving group. Chitosan feeding for 2 weeks caused a decrease in mineral absorption and bone mineral content, and it was necessary to administer twice the amount of Ca in the AIN-76 formula, which was supplemented with AsN, to prevent such a decrease in the bone mineral content. Moreover, the ingestion of chitosan along with AsN led to a marked and rapid decrease in the serum vitamin E level, while such a loss in vitamin E was not observed for rats given glucosamine monomer instead of chitosan.

Animals↗
PubMed1995

Effect of the viscosity or deacetylation degree of chitosan on fecal fat excreted from rats fed on a high-fat diet.

Several chitosan preparations, either with a comparable degree of deacetylation but differing viscosity or with comparable viscosity but a differing degree of deacetylation, were examined for their effect on the fecal fat excreted from rats fed on a high-fat diet. As the viscosity or deacetylation degree of a chitosan preparation increased, the more its effect on the apparent fat digestibility by rats became conspicuous. A supplement of ascorbic acid to each chitosan diets resulted in a significant depression of fat digestion and absorption in the lumen. The chitosan intake caused a higher level of fat to be excreted in the feces of the corn oil-receiving rats than the lard-receiving ones, although the effect was strong with both diet groups.

Acetylation↗
PubMed1995

Mechanism for the inhibition of fat digestion by chitosan and for the synergistic effect of ascorbate.

We investigated the mechanism for the inhibition of fat digestion by chitosan, and the synergistic effect of ascorbate. The important inhibition characteristics of fat digestion by chitosan from observations of the ileal contents were that it dissolved in the stomach and then changed to a gelled form, entrapping fat in the intestine. The synergistic effect of ascorbate (AsA) on the inhibition of fat digestion by chitosan is thought not to be acid-dependent but due to the specificity of AsA itself, according to the data resulting from using preparations supplemented with sodium ascorbate (AsN). The mechanism for the synergistic effect is considered to be 1) viscosity reduction in the stomach, which implies that chitosan mixed with a lipid is better than chitosan alone, 2) an increase in the oil-holding capacity of the chitosan gel, and 3) the chitosan-fat gel being more flexible and less likely to leak entrapped fat in the intestinal tract.

Animal Nutritional Physiological Phenomena↗
PubMed1995

Chromosomal localization of a strain-specific p53-related sequence in rat (Rattus norvegicus).

Strain-specific restriction fragments hybridizing to human p53 gene cDNA, which was detected in only particular strains of inbred rat were revealed by Southern blot hybridization of DNAs of various inbred rat strains. Chromosomal location of the strain-specific fragments was determined on rat chromosome 1 between Kal and Pkc loci by linkage analysis using microsatellite marker loci. The fragments were concluded to be a novel p53-related sequence which is present in particular rat strains and absent from the remaining strains.

Animals↗
PubMed1995

The clecarmycins, new antitumor antibiotics produced by Streptomyces: fermentation, isolation and biological properties.

In the course of screening for microbial products with antitumor activity, new antitumor agents, clecarmycins, were isolated from culture broth of Streptomyces sp. DO-114. The antibiotics were produced in a fermentation medium supplemented with a highly porous polymer resin which adsorbs antibiotics and results in a increase of titer. Active materials were separated from the polymer resin by solvent extraction procedure and two components named clecarmycin A1 and C were isolated by silica gel column chromatography. These were active against bacteria, and showed antiproliferative activities against human HeLa S3 cells. Clecarmycins exhibited antitumor activity against leukemia P388 and sarcoma 180 in mice.

Animals↗
PubMed1995

Migration of donor cells into the thymus is not essential for induction and maintenance of systemic tolerance after liver transplantation in the rat.

In this study, we show that cells encoded by donor-type major histocompatibility complex (MHC) class I antigens effectively migrate into the thymus of the host after liver transplantation. However, the thymus is not essential for the induction and maintenance of tolerance after orthotopic rat liver transplantation (OLT). Liver allografted rats in the DA(RT1a) into PVG (RT1c) combination survived without immunosuppressive agents. The thymus of the host showed a transitory atrophy and returned to normal weight 4 weeks after OLT. Donor antigens were detected in the host thymus after OLT. Adult PVG rats that had been thymectomized 1 week before implantation of DA liver grafts showed liver graft survival without immunosuppression. DA heart grafts were heterotopically transplanted into the PVG thymectomized, liver-grafted rats 1-4 weeks after OLT. No rejection of the cardiac allografts was observed. Systemic tolerance was induced and maintained in the absence of the thymus.

Animals↗
PubMed1995

[A case of atypical hemifacial spasm without involvement of orbicularis oculi muscles: possibility of functional topography in facial nerve].

We reported a case of atypical hemifacial spasm that did not involve orbicularis oculi muscles. A 60-year-old woman suffered from intermittent involuntary movement of the orbicularis oris and buccinator muscles. Operative findings revealed that the rostrodorsal portion of the facial nerve root was compressed by a loop of AICA. Transposing this AICA, it was found that it was compressing one portion on the rostrodorsal part of this nerve root. In most cases, facial spasm involves orbicularis oculi muscles and compression of the anatomically caudal portion of the facial nerve root. Differentiation of the compressed portions of the nerve, therefore, may indicate a functional topography of the facial nerve.

Facial Muscles↗
PubMed1995

KRN7000, a novel immunomodulator, and its antitumor activities.

KRN7000, a compound with a novel alpha-galactosylceramide structure, showed potent tumor growth inhibitory activities in B16-bearing mice and markedly stimulated lymphocytic proliferation in allogeneic mixed leukocyte reaction, suggesting that KRN7000 is a biological response modifier. To confirm this suggestion, we examined the abilities of KRN7000 to enhance in vitro and in vivo natural killer (NK) activities, and found that KRN7000 enhanced in vitro and in vivo NK activities, and its potency on in vivo NK activity was much stronger than those of Poly I:C, which is a positive control, or the representative BRMs OK432 and Lentinan. In addition, since spleen cells intravenously treated with KRN7000 also showed potent cytotoxic activities against B16 and EL-4 cells, we evaluated the capability of KRN7000 to prolong the survival period of mice intravenously inoculated with B16 cells or mice intraperitoneally inoculated with EL-4 cells. In these models, KRN7000 (100 micrograms/kg) significantly prolonged the lifespan of mice, and its potency was stronger than that of Mitomycin C, a typical chemotherapeutic agent, in two models. These results demonstrate that KRN7000 would be a useful agent for cancer therapy.

Adjuvants, Immunologic↗
PubMed1994

Induction of natural chimerism after retransplantation of the liver in rats.

Immunological aspects after orthotopic rat liver retransplantation (re-OLT) were examined in association with cell migration and mixed chimerism. At day 2 after the first orthotopic liver transplantation (day 0) in the combination of DA (MHC haplotype, RT1a) donor into PVG (RT1c) recipient, the grafted DA liver was removed and a new PVG liver was implanted into the same PVG recipient (re-OLT). In the PVG recipient at various times after the re-OLT, DA-derived antigen and cells were detected using a DA-specific anti-class I mAb R3/13 in conjunction with ELISA, immunoblotting, and immunohistochemistry. The level of soluble class I antigen, which had risen to 270 ng/ml after the first OLT, substantially decreased within 24 hr after re-OLT. Using immunoblotting, DA class I antigen was detected in the PVG recipient's lymphoid organs at day 3 after DA liver grafting and persisted for up to 21 days after the DA liver was replaced by a new PVG liver. Immunohistochemistry on sections of spleen from re-OLT rats showed that the level of migratory cells expressing DA class I correlated with the findings obtained by immunoblotting. While the DA-derived antigen and cells were detected in the re-OLT recipient, the DA-specific inhibition of mixed lymphocyte reaction was observed in re-OLT serum. Our results suggest that the implanted DA liver graft was the source of DA soluble class I antigen, but DA-derived antigen and cells detected in the re-OLT recipient organs could persist for a relatively long time under immunosuppression after the implanted DA liver was removed by re-OLT.

Animals↗
PubMed1994

The predisposing gene of the Eker rat inherited cancer syndrome is tightly linked to the tuberous sclerosis (TSC2) gene.

The Eker rat is a promising animal model of cancer predisposition syndromes. In this study, using 129 backcross animals, we have established a new conserved linkage group on rat 10q and human 16p13.3 whereby the Eker mutation was found to be tightly linked to the tuberous sclerosis (TSC2) gene. This will be the first step toward the positional cloning and identification of the predisposing Eker mutation.

Animals↗
PubMed1994

Molecular and crystal structure of (2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-(1-->3)- [2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl-(1-->6)]- (2,4-di-O-acetyl-beta-D-glucopyranosyl)- (1-->3)-1,2,4,6-tetra-O-acetyl-beta-D-glucopyranose.

Crystals of the tetrasaccharide, (2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-(1-->3)- [2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl-(1-->6)]- (2,4-di-O-acetyl-beta-D-glucopyranosyl)-(1-->3)- 1,2,4,6-tetra-O-acetyl-beta-D-glucopyranose, belong to the monoclinic system, space group P2(1), with a = 12.709(4), b = 27.767(9), c = 9.567(4) A, beta = 105.07(2) degrees, and Z = 2. The crystal structure was solved by the direct method and refined by the full-matrix least-squares procedure to an R-value of 0.071 for 302- observed reflections in the X-ray data. All the four D-glucopyranose residues have the usual 4C1 chair conformations. The torsional angles at two (1-->3)-beta-linkages were phi(O-5-1-O-1-C-3) = -74 degrees and psi (C-1-O-1-C-3-C-2) = -122 degrees between the nonreducing and the middle residues, and phi = -67 degrees, psi = -111 degrees between the middle and the reducing residues. The orientation about the (1-->6)-beta-linkage was found to be phi(O5-C1-O-1-C-6) = -77 degrees, theta(C1-O-1-C-6-C-5) = 160 degrees, and chi(O-1-C-6-C-5-O-5) = 63 degrees (gt conformation). The primary acetate groups at C-6 of the reducing and the (1-->6)-branched residues were in the gt conformations (O-5-C-5-C-6-O-6 = 81 degrees and 84 degrees, respectively). On the other hand, the gg conformation was observed for the primary acetate group in the nonreducing residue (O-5-C-5-C-6-O-6 = 78 degrees).

Carbohydrate Conformation↗