Biomedical subjects

M Kimoto

Publications and source records attributed to M Kimoto.

At least 145 records · Page 8Linked to original sources

PubMed1990

Structure of the murine mb-1 gene encoding a putative sIgM-associated molecule.

Genomic DNA clones containing the B cell-specific murine mb-1 gene were isolated and a 5.6-kb BamH I fragment was characterized. It is 5629 bp long and contains five exons: an exon containing the 5' untranslated and the coding sequence of the signal peptide, an exon of 294 bp, which contains most of the extracellular sequence of the MB-1 protein, a 119-bp long exon coding mainly for the transmembrane portion, and two exons of 69 bp and 427 bp encoding the cytoplasmic domain and the 3'-untranslated region, respectively. The mb-1 gene does not contain a "TATA box" found in many eukaryotic promoters. The 5'-flanking region has sequence stretches homologous to IgVH 5'-promoter regions and a bcl 2 intron sequence. It contains the decanucleotide sequence (ATGGCAAATA) almost identical to the octamer motif of IgVH promoters. A B cell-specific DNase I-hypersensitive site was found in the 3'-flanking region indicating that this region might be involved in B cell-specific expression of mb-1. Southern blot analysis of genomic liver DNA with the cloned mb-1 cDNA suggests the existence of another mb-1-related gene segment.

Amino Acid Sequence↗

PubMed1990

Direct evidence for the contribution of the unique I-ANOD to the development of insulitis in non-obese diabetic mice.

Insulin-dependent diabetes mellitus is characterized by the infiltration of lymphocytes into the islets of Langerhans of the pancreas (insulitis) followed by destruction of insulin-secreting beta-cells leading to overt diabetes. The best model for the disease is the non-obese diabetic (NOD) mouse. Two unusual features of the class II major histocompatibility complex (MHC) of the NOD mouse are the absence of I-E and the presence of unique I-A molecules (I-ANOD), in which aspartic acid at position 57 of the beta-chain is replaced by serine. This feature is also found in the HLA-DQ chain of many Caucasians with insulin-dependent diabetes mellitus. We have previously reported that the expression of I-E prevents the development of insulitis in NOD mouse. Here we report that the expression of I-Ak (A alpha kA beta k) in transgenic NOD mice can also prevent insulitis, and that this protection is seen not only when the I-A beta-chain has aspartic acid as residue 57, but also when this residue is serine. These results show that the single amino-acid substitution at position 57 of the I-A beta-chain from aspartic acid to serine is not sufficient for the development of the disease.

Animals↗

PubMed1990

Antigen-reactive T cell clones restricted by mixed isotype A beta d/E alpha d class II molecules.

Mixed isotype A beta dE alpha d class II molecule-restricted antigen-reactive T cell clones were obtained from (BALB/c x B6E alpha d)F1 mice. These T cell clones responded to keyhole limpet hemocyanin in the presence of (BALB/c x B6E alpha d)F1 but not CBF1 APCs. Both anti-A beta d and anti-E alpha mAbs blocked the proliferative responses of these clones. The frequency of such mixed isotype A beta E alpha-restricted T cell clones in (BALB/c x B6E alpha d)F1 mice was estimated to be approximately 10% from our limiting dilution cloning. The existence of such mixed isotype class II molecule-restricted T cells would have important implications for the expansion of the T cell repertoire as well as the induction of autoimmunity.

Animals↗

PubMed1990

Postoperative recovery of mitochondrial function of the human liver graft procured and preserved with University of Wisconsin (UW) solution.

Changes in arterial blood ketone body ratio (KBR) were investigated in 47 human liver transplantations. Of the 20 grafts preserved with University of Wisconsin (UW) solution, 10 had a cold preservation period of less than 10 h (UWS group) and 10 of more than 10 h (UWL group). In 27 other cases, grafts were preserved with EuroCollins (EC) solution for less than 10 h (EC group). In the EC group, KBR increased over 0.7 within 6 h after reperfusion of the graft in 17 cases (63%) and within 24 h in 7 cases (26%). In the 3 other cases, KBR failed to recover, and these patients underwent retransplantation. In the UW group, KBR recovered within 6 h in 13 cases (65%) and within 24 h in 7 cases (35%). There were no significant differences between the UWS and UWL groups. It is shown that the mitochondrial function of liver grafts preserved with UW solution can be well maintained even after extended preservation periods of more than 10 h.

Adenosine↗

PubMed1990

T cell clones are killed by a thymic stromal cell monolayer following stimulation of T cell receptor with antigen and/or H-2 molecules on the monolayer.

A thymic stromal cell clone, MRL104.8a, expressed class I and class II H-2k antigens after exposure to gamma-interferon (gamma-IFN) and produced thymic stroma-derived T cell growth factor (TSTGF) irrespective of gamma-IFN exposure. Culturing the keyhole limpet hemocyanin (KLH)-specific, I-Ek-restricted 9-16 helper T cell (Th) clone on an Ia (I-Ak and I-Ek)-expressing MRL 104.8a monolayer induced potent proliferation of the 9-16 cells by virtue of the TSTGF produced by the monolayer. In contrast, the addition of KLH to cultures resulted in lethal growth inhibition of the 9-16 Th clone. Such a phenomenon was also observed for various Th as well as cytotoxic T lymphocyte (CTL) clones, and the following were revealed: (i) the growth of the ovalbumin (OVA)-or bovine thyroglobulin (BTg)-specific Th clone on the la-expressing MRL 104.8a monolayer was also inhibited by addition of the relevant antigen. The fact that these Th clones required antigen-presenting cells (APC) capable of processing antigen for the recognition of the respective target antigen suggested the potential of MRL 104.8a cells for antigen-processing; (ii) the lethal growth inhibition of KLH-specific, I-Ak (23-1-8)- or I-Ek (9-16)-restricted Th clone was prevented selectively by anti-I-Ak or anti-I-Ek antibody respectively; (iii) the I-Ek-alloreactive Th clone (2-13) was supported for its growth on a gamma-IFN-unexposed MRL 104.8a monolayer, whereas this clone was killed on an I-Ek-expressing monolayer; and (iv) when I-Ak-reactive CTL clones were cultured on an Ia- or Ia+ monolayer, CTL clones failed to exhibit cytotoxic effect on either the Ia- or the Ia+ monolayer, but were conversely killed by the Ia+ monolayer. Its killing was also prevented by an antibody which inhibits the recognition of Ia antigen on the monolayer by CTL clones.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Cholesterol-lowering activity of various undigested fractions of soybean protein in rats.

The undigested high-molecular-weight fraction (HMF) of soybean protein prepared after exhaustive digestion by microbial proteases significantly decreased serum cholesterol levels to approximately 45% (p less than 0.05) of those observed with the parent protein in rats fed diets containing cholesterol (0.5%) and sodium cholate (0.125%). HMF bound conjugated bile salts in vitro and significantly increased fecal excretion of both neutral and acidic steroids by 65-95% and 80-170% more, respectively (p less than 0.05), than did the intact protein. Extraction of HMF with methanol slightly decreased the activity, but the methanol-soluble fraction was not regarded as a principal determinant. Soybean saponin at the dietary level equivalent to that contained in HMF did not effectively lower serum cholesterol. The activity was not necessarily duplicated even when methanol-treated fractions were recombined. Further degradation of the methanol-extracted HMF by various proteases resulted in loss of activity. HMF obtained after pepsin digestion exerted a potential similar to that of HMF prepared after digestion by microbial proteases.

Animals↗

PubMed1990

Existence of mixed isotype A beta E alpha class II molecules in Ed alpha gene-introduced C57BL/6 transgenic mice.

In this study the existence of mixed isotype Ab beta Ed alpha molecules in Ed alpha gene-introduced C57BL/6 (B6Ed alpha) transgenic mice is demonstrated. Biosynthetically labelled B6Ed alpha transgenic spleen cells were immunoprecipitated with anti-Ab beta or anti-Ed alpha monoclonal antibody (mAb) and analysed by two-dimensional gel electrophoresis (NEPHGE/SDS-PAGE). Anti-Ab beta mAb precipitated Ed alpha molecules in addition to Ab beta and Ab alpha molecules. Anti-Ed alpha mAb precipitated Ab beta molecules in addition ot Eb beta and Ed alpha molecules. No Ed alpha molecule was precipitated by anti-Ab beta mAb from B10.A(3R) spleen cells, which have a very similar organization of class II molecules to B6Ed alpha transgenic mice. Since this B6Ed alpha transgenic mouse was shown to have 20-40 copies per cell of the Ed alpha transgene (Kashiwamura et al., 1988), it is speculated that large amounts of Ed alpha transgene are made but, according to the data presented here, only a small amount actually associates with Ab beta as opposed to Eb beta.

Animals↗

PubMed1989

Purification and properties of a new enzyme, NG,NG-dimethylarginine dimethylaminohydrolase, from rat kidney.

A new enzyme, NG, NG-dimethylarginine dimethylaminohydrolase which plays a role in the metabolism of NG,NG-dimethyl-L-arginine, has been purified to homogeneity from rat kidney. The enzyme consists of a single polypeptide and its molecular weight is about 33,000. The isoelectric point of the enzyme is at pH 5.2. The enzyme catalyzes the hydrolytic liberation of the dimethylamino moiety of NG,NG-dimethyl-L-arginine and forms L-citrulline and dimethylamine. It is highly specific for NG,NG-dimethyl-L-arginine and NG-monomethyl-L-arginine, and the Km values for these amino acids are 0.18 and 0.36 mM, respectively. The enzyme shows the maximum activity at pH 6.5 and requires no cofactor. The activity is strongly inhibited by SH-blocking reagents (e.g. p-chloromercuribenzoate and HgCl2) and divalent metal ions (e.g. Cd2+, Cu2+, and Zn2+).

Amidohydrolases↗

PubMed1989

Measurement of vitamin K in human liver by gradient elution high-performance liquid chromatography using platinum-black catalyst reduction and fluorimetric detection.

A sensitive and precise method for measuring endogenous phylloquinone (K1) and menaquinone (MK-n) in human liver was developed, based on gradient elution high-performance liquid chromatography using platinum-black catalyst reduction and fluorimetric detection. Subnanogram levels of vitamin K compounds in 1 g of liver specimen were detectable. We measured vitamin K concentrations in 38 human resected livers. K1 and MK-4 to MK-13 were detected. The concentrations of MK-10 to MK-12 in livers with chronic hepatitis (n = 10) and cirrhosis (n = 22) were significantly lower than in normal livers (n = 6). It is suggested that the decreased concentrations indicate functional damage of the hepatocytes.

Catalysis↗

PubMed1989

The effects of PGI2 analog (OP-41483) on perfused porcine liver.

The effects of a prostacyclin analog OP-41483 on energy metabolism were studied in an isolated porcine liver perfused with human blood for 8 h. OP-41483 was administered intravenously at a rate of 0.3 microgram/kg/min during the procurement and into the perfusate at a rate of 1.0 microgram/min during perfusion. Acetoacetate, beta-hydroxybutyrate, lactate, and pyruvate were measured before perfusion and at 1, 2, 3, 5, and 8 h after perfusion, from which values the ketone body ration (acetoacetate/beta-hydroxybutyrate, KBR), reflecting the redox state of liver mitochondria, was calculated. In the OP-41483 group, KBR increased rapidly from 0.34 to 0.95, 1.61, 1.51, 2.35, and 2.04, and lactate decreased rapidly from 9.81 to 6.30, 4.51, 3.22, 2.39, and 1.33 mmol/L at the respective hours after perfusion. There were significant differences after 3 h of perfusion as compared with the control group (p less than 0.05). These results suggest that administration of OP-41483 causes an increase in mitochondrial NAD+/NADH ratio (oxidized and reduced forms of free nicotinamide-adenine dinucleotides), leading to an enhancement of the metabolic capacity of the perfused liver.

3-Hydroxybutyric Acid↗

PubMed1989

Changes in serum bile acid composition in relation to histological findings after liver transplantation in piglets.

Changes in the composition of serum bile acids were investigated after orthotopic liver transplantation in piglets. Serum levels of all bile acid components rapidly increased during the anhepatic phase and then quickly decreased, returning to the preoperative state within 6 h of revascularization of the allograft. In the animals in which extrahepatic biliary stenosis was a complication, serum total bile acids (TBA) increased remarkably. A marked increase of hyocholic acid and marked decrease of hyodeoxycholic acid were noted; as percentages of TBA, the average levels per day were 91.3 +/- 1.3 and 5.0 +/- 1.3%, respectively. No change in chenodeoxycholic acid (CDCA) was observed. In the animals suffering acute rejection without extrahepatic biliary stenosis, serum TBA increased slightly and the percentage of CDCA rose, the average level being 29.6 +/- 1.5%. These results suggest that the measurement of the composition of serum bile acids may serve as a useful means of assessing allograft function after liver transplantation.

Animals↗

PubMed1989

Cryosurgical treatment for anorectal cancer. A method of palliative or adjunctive management.

Thirty-two patients with anorectal cancer were treated with cryosurgery from April 1974 to August 1985. The purpose of the treatment was to provide palliative benefits to 27 patients. In one group (17 patients) who did have previous surgery, cryosurgery was used for the predominant symptoms of melena and/or obstruction. In the postoperative period, local bleeding was minimal, and palliation was judged significant. The survival time of this group ranged from 1 month to 18 months. In another group (10 patients) in whom recurrent cancer followed previous operative treatment, cryosurgery was used to control the local invasion and tumor bulk. All of these patients died within 17 months after recurrence was discovered. Nevertheless, treatment was judged to provide significant palliation. A small group (five patients) was treated with the intent to cure, and cryosurgical techniques were used as an adjunct to surgical excision. Four patients survived more than 8 years after the operation. Two of these patients died of illnesses other than cancer. The local destruction of an anorectal cancer by cryosurgery in these patients provided effective control of the tumor. Bleeding was controlled, and tumor bulk was reduced in size. All patients were treated without any complications caused by cryosurgery. This experience indicates that the cryosurgical technique provides therapeutic benefits for selected patients with anorectal cancer, especially those of high surgical risk.

Adult↗

PubMed1989

Unique mixed lymphocyte-stimulating determinants in Ed alpha gene-introduced C57BL/6 transgenic mice.

A unique mixed lymphocyte-stimulating determinant(s) was detected in Ed alpha gene-introduced C57BL/6 transgenic mice using alloreactive T-cell clones. Such unique determinant(s) was not detected by primary mixed lymphocyte culture reactions. The possibility that such unique determinant(s) was created by the combinatorial association of Ed alpha transgene products with endogenous Ab beta gene products is discussed.

Animals↗

PubMed1989

[Application of isocyanate separating agent for acrylic resin].

The most widely used agents for separating acrylic resin from gypsum molds are the water-soluble alginates, which produce a very thin water- and organic solvent-insoluble calcium alginate film on the gypsum surface. In the present study, a new type of separating agent, an isocyanate type coating agent, was developed and it's properties were investigated. This coating agent is composed mainly of trimethylol-propane-tolylenediisocyanate and ethyl-acetate, with a small amount of bis-tributyl-tin oxide as catalyst. At first, a thin film was formed on the surface by application of the agent, and then alkyl-phosphate was applied to this film to ensure easy separation of the cured resins from the molds. The molds treated with this separating agent had a glossy, hard surface. The surface of the cured resins treated in this way was glossier and smoother than that of resin treated with the water-soluble alginates.

Acrylic Resins↗

PubMed1989

Presence of a very small population of Thy-1+, L3T4+ cells producing large amounts of IL-3 in young athymic nude mice.

A mixture of phorbol myristate acetate (PMA) and ionomycin was found to stimulate spleen and lymph node cells (LNC) from 6 to 8 week-old-athymic BALB/c nude mice, as well as from control +/+ mice, to secrete interleukin-3 (IL-3) in vitro. The specificity of the IL-3 bioassay was attested to by the use of rabbit anti-IL-3 antibodies, and by the detection of an accumulation of IL-3 mRNA. Cytotoxic treatment with relevant antibodies showed that the cells responsible for the IL-3 production in athymic nude mice was Thy-1+, L3T4+, Ly2-, while both L3T4+ and Ly 2+ cells produced IL-3 in control +/+ mice. Although the levels of IL-3 secreted by nude LNC varied among experiments, nude LNC were able to produce IL-3 at a level comparable to or higher than +/+ LNC. In addition, nude LNC consistently secreted two to three times more granulocyte-macrophage colony-stimulating factor (GM-CSF) than +/+ LNC, and the majority of GM-CSF secretion was dependent on the presence of L3T4+ cells. In contrast, IL-2 production by nude LNC was markedly limited. Since the flow microfluorometry analysis failed to demonstrate the presence of L3T4+ cells (less than 1%) in nude LNC, compared with 40-50% L3T4+ cells in +/+ LNC, our results suggest that athymic nude mice have a small population of Thy-1+, L3T4+ cells characterized by its ability to secrete IL-3 and GM-CSF at a very high rate.

Animals↗

PubMed1989

Anti-IgM treatment of C57BL/6-1pr/1pr mice: depletion of B cells reduces 1pr gene-induced lymphoproliferation and mononuclear cell vasculitis.

In order to study the role of B cells in autoimmune abnormalities observed in C57BL/6 mice bearing the autosomal mutant gene 1pr (lymphoproliferation), we treated mice from birth continuously with rabbit anti-IgM antiserum. Anti-IgM treatment resulted in the complete suppression of B cell development, documented by the absence of surface Ig-positive cells, the lack of lipopolysacchride-induced mitogenic responses, and the lack of autoantibody production. Although, anti-IgM-treated C57BL/6-1pr/1pr mice developed 1pr gene-associated lymphoproliferation due to the accumulation of Thy-1+, CD4-, CD8-, B220+ T lymphocytes in spleen and lymph nodes, the size of their spleen and lymph nodes was considerably smaller than that of normal rabbit serum-treated C57BL/6-1pr/1pr mice. Systemic vascular lesions associated with mononuclear cell infiltration were a little affected by anti-IgM treatment. This indicates that the development of mononuclear cell vasculitis in mice bearing the 1pr gene may be associated with the 1pr gene-induced lymphoproliferation and is independent of B cells and autoantibody production.

Animals↗

PubMed1988

Recombinant murine IL-3 fails to stimulate T or B lymphopoiesis in vivo, but enhances immune responses to T cell-dependent antigens.

We have explored the in vivo effect of IL-3 on the lymphopoiesis and humoral responses of mice bearing osmotic minipumps loaded with murine rIL-3 for 1 to 4 wk. A marked splenomegaly due to the accumulation of hemopoietic precursors was seen, but no increase was found in the lymphoid organs in the total number of cells belonging to the T or B lymphocyte lineage, i.e., of L3T4+ or Lyt-2+, or of allospecific cytotoxic T lymphocyte precursor for the T lineage, or of sIg+ or B220+ cells, or of B colony-forming cells for the B lineage; total activity of natural killer and lymphokine-activated killer cells was decreased. In contrast to the splenomegaly, a marked diminution in the number of thymocytes was observed, suggesting that rIL-3 in large amounts does suppress the T lymphopoiesis, perhaps as the result of the selective stimulation of early progenitor cells toward the hemopoietic pathway. rIL-3 perfusion during immunization increased the IgM and IgG responses to a T cell-dependent antigen, human IgG, and prevented tolerance induction by the deaggregated human IgG, although in the same conditions it did not modify the response to a T cell-independent antigen. Our results suggest that in vivo IL-3 does not act directly on lymphocytes or their precursors, but may potentiate the humoral immune response to T cell-dependent antigens, presumably by acting on accessory cells.

Animals↗

PubMed1988

Selective production of interleukin 3 (IL3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro by murine L3T4+ T cells: lack of spontaneous IL3 and GM-CSF production by Ly-2-/L3T4- lpr subset.

Murine spleen and lymph node L3T4+ T cells were found to spontaneously produce high levels of interleukin 3 (IL3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in cultures containing 10% fetal calf serum (FCS) in the absence of other stimulation. The IL3 and GM-CSF activities in culture supernatants peake between the fifth and seventh day of culture. The specificity of the bioassays was attested by the use of rabbit anti-IL3 and anti-GM-CSF antibodies, as well as by the detection of a maximal accumulation of IL3 and GM-CSF mRNA on the fourth day. In contrast, no significant activities of IL2, IL4 or interferon-gamma were detected in these culture supernatants. The markedly limited production of IL3 and GM-CSF in cultures performed in 1% autologous normal mouse serum and the inhibitory effect of anti-Ia or anti-L3T4 monoclonal antibody strongly suggest that the selective production of most, if not all IL3 and GM-CSF by L3T4+ T cells is a result of activation of L3T4+ T cells by fetal calf serum. All the strains of mice tested except athymic nude mice produced substantial amounts of IL3 and GM-CSF during the culture. This is in contrast to a previous report (Palacios, Eur. J. Immunol. 1984. 14: 599), indicating that only spleen cells of the MRL strain homozygous for the lpr gene spontaneously release IL3 in cultures. We found that spleen and lymph node cells from MRL/MpJ-lpr/lpr or C57BL/6J-lpr/lpr mice released, in fact, much less IL3 and GM-CSF in cultures. This was, however, due to the high proportion of the peculiar lpr Ly-2-/L3T4-T cells in spleen and lymph nodes, since after depletion of this lpr T cell subset, lymph node cells from C57BL/6J-lpr/lpr mice produced IL3 and GM-CSF at levels comparable to those in C57BL/6J-+/+ mice. These results further support the notion that the lpr Ly-2-/L3T4- T cell subset is immunologically nonfunctional and its accumulation dilutes functional L3T4+ T cells in mice bearing the lpr mutation.

Animals↗