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K Isobe

Publications and source records attributed to K Isobe.

At least 307 records · Page 17Linked to original sources
PubMed1985

Comparison of kinetic study of the photochemical changes of (ZZ)-bilirubin IX alpha bound to human serum albumin with that bound to rat serum albumin.

It has been stated by McDonagh, Palma & Lightner [(1982) J. Am. Chem. Soc. 104, 6867-6871] that complexing of bilirubin with serum albumin has a marked species-dependent influence on bilirubin photoisomerization in vitro and in vivo. Therefore the kinetics for the quantitatively important reaction: (Formula: see text) of the photochemical interconversion between bilirubin and its photoisomers bound to human or rat serum albumin in aqueous solution, assayed by h.p.l.c., was used to elucidate the observed species-dependent difference. The relative rate constants for bilirubin bound to human serum albumin, except for k4, the rate of interconversion from (ZZ)-bilirubin into (EZ)-bilirubin, proved to be considerably larger than those for bilirubin bound to rat serum albumin. In accordance with these rate constants, the formation of photoisomers of bilirubin bound to human serum albumin, except for (EZ)-bilirubin, is very rapid and much greater than that for bilirubin bound to rat serum albumin.

Animals↗
PubMed1985

Genetic and stimulatory cell type requirements for inducing class I major histocompatibility complex alloantigen-specific in vivo cytotoxic T cell immunity.

Current interpretation based on analytical in vitro works that actions of Ia antigens and accessory cells such as macrophages and dendritic cells are crucial for inducing cytotoxic T cell responses to class I major histocompatibility complex (MHC) alloantigens has been challenged by experiments performed in a newly developed system handling in vivo cytotoxic T cell immunity. We first characterized the transplantation immunity for second-set rejection of ascitic tumor allografts as principally induced by allogeneic stimulator cells via direct pathway, and as exclusively mediated by class I MHC alloantigen-specific in vivo cytotoxic T cell activity. By comparison of activities of limiting effective doses (10(4)-10(5) cells per mouse) of various stimulator cells in this defined system, we could demonstrate that genetic disparity at the D region of H-2 to the recipient is just enough for inducing the immunity, and presence of allogeneic or syngeneic Ia antigens in addition to H-2D alloantigens on stimulator cells does not give any premium effect. Further study revealed that allogeneic peritoneal cells rich in macrophages or glass-adherent spleen cells enriched for dendritic cells are not stronger stimulators than allogeneic adherent cell-depleted spleen cells and semi-allogeneic thymocytes. These results fit with the alternative concept that the physiological pathway inducing in vivo cytotoxic T cell immunity for graft rejection entirely depends on class I MHC antigens on live lymphocytes as self-supported stimulators, and does not crucially involve additional stimulator activities of Ia antigens and special accessory cell types, which must be in vivo concerned with induction of other types of transplantation immunity.

Animals↗
PubMed1985

Structure of the murine Thy-1 gene.

We have cloned the murine Thy-1.1 (AKR) and Thy-1.2 (Balb/c) genes. The complete exon/intron structure and the nucleotide sequence of the Thy-1.2 gene was determined. The gene contains four exons and three intervening sequences. The complete transcriptional unit gives rise to a tissue and developmental stage-specific mRNA of 1850 bp. The 5' end of the gene has multiple initiation sites and a non-TATA box promoter. The 3' end shows a single polyadenylation site after a very long untranslated region.

Amino Acid Sequence↗
PubMed1985

An enzymatic differential assay for urinary diamines, spermidine, and spermine.

Subsequent to the hydrolysis of urinary conjugated amines by heating with hydrochloric acid, free amines were isolated by cation-exchange chromatography. SPD and SPM in an aliquot of amine extract were first oxidized by PAO from Penicillium chrysogenum, producing PUT and hydrogen peroxide. DIAs, which consist of the initially present DIAs plus PUT produced by PAO, were subsequently oxidized by PUO from Micrococcus rubens, producing hydrogen peroxide. In an another aliquot of the amine extract DIAs and SPD were oxidized by PUO, producing hydrogen peroxide. Quinone dye, derived from hydrogen peroxide generated in each end-point reaction, was measured spectrophotometrically at 555 nm, and the amounts of the respective amines in urine were calculated. Significantly elevated levels of DIA, SPD, SPM, and an elevated DIA to SPD ratio were found in urine from 46 cancer patients, as compared to 34 normal control subjects. An increase in DIA and the ratio of DIA to SPD was found at clinical tumor stage I of the alimentary tract. The levels of DIA remained fairly constant and the ratio of DIA to SPD was consistently decreased with advancing clinical tumor stages. In patients who had undergone curative resection, there were greater decreasing rates (80% of cases for DIA and 80% for SPD) than in patients who had undergone noncurative resection (45.5% for DIA and 36.4% for SPD).

Diamines↗
PubMed1985

Simultaneous development of humoral and cellular tumor-specific immunity against L1210 mouse leukemia.

We have recently described that a variant of L1210 leukemia cell (L1210/LN-1) originally fused with Lesch-Nyhan fibroblast is highly immunogenic for inducing tumor-specific transplantation immunity in (BALB/cxDBA/2)F1 mice. This finding has clearly been confirmed in the present study by in-vitro cell-mediated cytotoxicity assay. Direct cytotoxic tests and competitive inhibition tests using tumor cells such as P388, LS-1 and L5178Y as target or inhibitor cells showed that the cell-mediated immunity is specific to L1210 leukemia. In the process of this study, we found that the CD2F1 mice hyperimmune to L1210 leukemia cells developed co-existing humoral anti-L1210 leukemia immunity. In an in vitro complement-dependent cytotoxicity test and absorption test, antisera from hyperimmune mice reacted specifically to L1210 leukemia cells, but not other tumor cells such as P388, L5178Y, LS-1, DB27C and BW5147 or normal cells from various tissues of DBA/2, BALB/c and AKR mice. In an in vitro cytotoxicity blocking test, the cytotoxic antisera specifically reactive to L1210 cells totally failed to inhibit lysis of L1210 cells by cytotoxic cells, suggesting that antigens recognized by cell-mediated cytotoxicity assays are not identical to serologically defined tumor-cell surface antigens.

Animals↗
PubMed1985

Ontogeny of the transplantation immunity of mice for rejecting ascitic allogeneic tumors.

Ontogeny of the murine transplantation immunity for rejecting ascitic allogeneic tumors (chemically-induced RG lymphoma and L1210 leukemia) as a model of in vivo cytotoxic T cell immunity was studied. Challenge by 10(6) to 10(7) allogeneic tumor cells per 20 g body weight (b.w.) of the mouse was fatal to 1-3 day-old mice, whereas 7-30 day-old mice rejected the tumor. In newborn mice however some yet undetermined mechanism worked to temporally depress the initial tumor growth. Injection of low (10(6) cells per 20 g b.w.) to moderate (10(7)) doses of semiallogeneic spleen cells into newborn mice prepared for second set rejection of the tumor carrying the same alloantigens as the spleen cells, although injection of high dose (3 X 10(8)) cells reduced the tumor rejecting immunity. This second set rejection occurred even against the allogeneic tumor inoculated as early as 3 days old, if the mice had been primed with the alloantigens at birth. It appears therefore that newborn and early suckling mice are protected from tumor invasion by cytotoxic immunity more powerfully than expected from earlier in vitro works.

Age Factors↗
PubMed1985

Immune reactivity of allogeneically pregnant mice to paternal MHC antigens on fetal and placental cells assessed by second set rejection of ascites tumor cells.

In vivo immunogenicity of fetus- and placenta-derived cells as well as the immune reactivity of pregnant mice to fetal cells were examined for graft rejecting response (GRR). Systemic administration of small numbers of fetal cells but not placental cells from allogeneically pregnant mice (10(6) cells per mouse) or adult allogeneic spleen cells (10(4) cells) sensitized mice for second-set rejection of an ascitic tumor bearing paternal major histocompatibility complex (MHC) antigens. Despite this fact and the known positive humoral response, pregnant and parous mice are not even minimally sensitized with fetal MHC antigens for GRR transplacentally. Nevertheless, any pregnancy-related systemically active control, which would selectively prevent the mother from being sensitized for GRR by limiting numbers of semi-allogeneic fetal cells, was not demonstrable in either allogeneically or syngeneically pregnant mice. Irrespective of pregnancy, mice did not, however, respond to repeated administration of very small numbers of allogeneic spleen cells (5 X 10(2) cells per mouse) for graft rejection. These findings support the notion that deviation of maternal immunity to fetal antigens away from harmful GRR is mediated principally by local mechanisms which inhibit fetal cells from gaining access to the mother for GRR, and additionally by the innate inability of mice to respond to very small numbers of allogeneic cells that might escape past the local maternal-fetal barrier.

Animals↗
PubMed1985

Direct activation of Sendai virus (HVJ)-specific cell-mediated immunity of mice for second set rejection of the virus-infected syngeneic tumor by noninfectious virus-sensitized spleen cells.

Syngeneic spleen cells (SPC) sensitized in vitro with noninfectious NVJ were shown to effectively stimulate mice to generate the HVJ-specific cell-mediated immunity for second set rejection (SSR) of virus-infected syngeneic leukemia cells. As few as 10(4) live but not disrupted SPC either infected with a temperature-sensitive mutant of HVJ (HVJts) or sensitized passively with ultraviolet (UV)-inactivated HVJts were active as immunogen. Syngeneic SPC as the carrier of virus could be replaced by allogeneic SPC or L cells, a fibroblast cell line, without reduction of the immunogenicity. Further study demonstrated that a special density of antigen on the surface of HVJts-sensitized SPC is required for high immunogenicity. It was suggested that live cells appropriately sensitized with noninfectious virus would serve as an excellent vaccine for virus-specific cell-mediated immunity.

Animals↗
PubMed1985

Pharmacological characteristics of four giant neurons identified in the cerebral ganglia of an African giant snail (Achatina fulica Férussac).

Two giant neurons, d-RCDN (dorsal-right cerebral distinct neuron) and d-LCDN (dorsal left cerebral distinct neuron), with a diameter of about 100 microns, were found symmetrically on the dorsal surface of the cerebral ganglia of an African giant snail (Achatina fulica Férussac). They showed spontaneous spike discharges at a stable frequency. Two giant neurons, v-RCDN (ventral-right cerebral distinct neuron) and v-LCDN (ventral-left cerebral distinct neuron), (diameter, approx. 150 microns) were identified on the ventral surface of the same ganglia. No spontaneous spike discharges were evident. Both d-RCDN and d-LCDN were equally inhibited by dopamine, octopamine, 5-hydroxytryptamine and histamine. Acetylcholine sometimes showed inhibitory effects, but they were not so stable. No substance having excitatory effects on the neurons was found. Both v-RCDN and v-LCDN were equally excited by octopamine, 5-hydroxytryptamine, GABA and acetylcholine and inhibited by dopamine and beta-hydroxy-L-glutamic acid.

Acetylcholine↗
PubMed1985

Anti-Thy-1 antibody responses evoked by Thy-1 antigen expressed in transfected mouse mastocytoma cells and rat fibroblast.

The mouse genomic Thy-1.1 gene was isolated from a phage library constructed from AKR/J (Thy-1.1) mouse DNA. Partial nucleotide sequence analysis of the coding region showed that it has only a single nucleotide difference from the Thy-1.2 gene, namely that amino acid 89 reads CGA (Arg) in Thy-1.1 and CAA (Glu) in Thy-1.2, corresponding to the amino acid substitutions previously identified. It was subcloned into an SV-40 derived vector for transfection. Transient transfection into HeLa cells gave 2% positive staining by immunofluorescence. The gene in this vector was also co-transfected into L cells and mastocytoma cells (both of Thy-1.2 strain origin) together with the Agpt gene. L-cell clones selected for transformation proved almost negative for Thy-1.1 expression, and any positive clones gradually lost Thy-1.1 antigen expression in culture. On the contrary, all clones of mastocytoma transformants gave a high level of expression after more than 3 months in culture. The mastocytoma transformants were used to study the immunogenicity of Thy-1.1 molecules expressed on transfected cells. They evoked clear anti-Thy-1.1 plaque-forming cell (PFC) responses both in vivo and in vitro. The mastocytoma transformants also proved able to induce a T-dependent anti-Thy-1.1 antibody response in a cell transfer experiment. The immunogenicity of Thy-1.2 molecules on rat fibroblasts was also studied after transfection with a Thy-1.2 gene cosmid. Although Thy-1.2 expression was very low, these transfectants elicited a clear anti-Thy-1.2 PFC response from AKR spleen cells hyperimmunized against CBA thymocytes.

Animals↗
PubMed1984

Biliary and urinary excretion rates and serum concentration changes of four bilirubin photoproducts in Gunn rats during total darkness and low or high illumination.

On cycled exposure of Gunn rats to total darkness and low and high illumination, biliary excretion rates of (EZ)- and (ZE)-bilirubin and (EZ)-cyclobilirubin increased up to approx. 10-fold from the mean basal values of 1.2 and 0.2 microgram/h to the mean maximum values of 25.2 and 4.2 micrograms/h respectively, and at the same time those of (EE)-bilirubin and (EE)-cyclobilirubin also increased, but at very much lower rates than those of the first-mentioned two. During the low illumination only (EZ)- and (ZE)-bilirubin and (EZ)-cyclobilirubin appeared in the urine; during the high illumination (EE)-bilirubin and (EE)-cyclobilirubin also appeared, showing a similar excretion pattern to that observed in the bile, but the total urinary excretion rates were lower than the total biliary excretion rates. The serum bilirubin concentrations fell gradually to lower values, accompanied by an increment in (EZ)- and (ZE)-bilirubin, but (EZ)-cyclobilirubin was not detected. It is concluded that during phototherapy the predominant pathway for the removal of bilirubin from the body in the Gunn rat is by biliary excretion of the geometric photoisomers (EZ)- and (ZE)-bilirubin, derived from Z----E isomerization, and the structural photoisomer (EZ)-cyclobilirubin, formed from intramolecular endo-vinyl cyclization.

Animals↗
PubMed1984

Significance of the endo-vinyl group of bilirubin in photochemical reactions.

In photochemical experiments on bilirubin III alpha (no endo-vinyl group), IX alpha (one endo-vinyl group) and XIII alpha (two endo-vinyl groups) and in the photochemical, thermal and catalytical reversion of their photoproducts under anaerobic conditions, much more instability and complexity of photoproducts of bilirubin XIII alpha were observed than for those of bilirubin IX alpha or III alpha. On the basis of present and previous results of photochemical experiments in vitro and the fact that large amounts of (EZ)-cyclobilirubin IX alpha appear in the bile during phototherapy of neonatal hyperbilirubinaemia [Onishi, Kawade, Itoh, Isobe & Sugiyama (1980) Biochem. J. 190, 527-532], it is concluded that the endo-vinyl group plays a crucial role in the photochemical reaction of bilirubin IX alpha. On reversed-phase high-pressure liquid chromatography of photoisomers, it was found that the retention times of geometric isomers and E-cyclized structural isomers were shortened compared with those of Z-isomer and E-isomer, respectively, as precursor substances.

Bilirubin↗
PubMed1984

Structure and thermal interconversion of cyclobilirubin IX alpha.

One of the two main photoproducts in bilirubin metabolism during phototherapy in neonatal hyperbilirubinaemia is (EZ)-cyclobilirubin. However, it has not yet been possible to come to a final conclusion as to its chemical structure, despite the fact that much effort has been expended on the problem. The present paper demonstrates that (EZ)-cyclobilirubin is formed by the intramolecular cyclization of the C-3-vinyl group with the position at C-7 rather than at C-6, without delta-lactone-ring formation. The evidence comes from 13C-n.m.r. spectra, which indicate that an oxygen-bound quaternary carbon atom is not present, and from 1H-n.m.r. spectra, which indicate that the orientation of the methyl group at C-2 is equatorial; these findings are supported by mass spectra. The existence of both an epimeric relationship at C-7 between (EE)- and (EZ)-cyclobilirubins A and B and of steric isomers of the hydrogen atom and methyl group at C-2 is supported by the fact that the methyl-group protons at C-2 and C-7 are observed as a paired signal in 1H-n.m.r. spectra, and that new signals at C-7, C-2 and C-3 beta appear in 13C-n.m.r. spectra, that mass spectra of (EZ)-cyclobilirubins A and B are extremely similar and that, furthermore, thermal interconversion between (EE)- and (EZ)-cyclobilirubins A and B is observed.

Bilirubin↗
PubMed1984

Genetic controls of T cell-independent Thy-1 alloantibody responses.

Early and late primary IgM antibody responses of mice to Thy-1.1 antigens showed different antigenic and cellular requirements. We studied genetic controls of the early primary responses, which could be induced by subcellular thymocyte antigens independently of host T-cell activity. All Thy-1.2 mouse strains of Igha (BALB/c and BC8), Igh-VaCb (BAB14), Ighd (AKR/Cum), Ighj (CBA/J, C3H/HeN, C3H.SW, and C3H.JK), and Ighn (NZB) definitely responded early to Thy-1.1 antigens from AKR/J (Ighd), A.Thy-1.1 (Ighe), or B10.Thy-1.1 (Ighb) mice or SD rats, whereas all strains of Ighb (C57BL/6, C57BL/10, B10.D2, B10.BR, B10.A, CB20 and CWB), Ighc (DBA/2), Ighe (A/J), and Igho (C.AL20) responded poorly to the same antigens. This contrasts with the observation that both strains of Ighj (C3H/HeN) and Ighb (B10.BR) responded well at later times. As was the case for late responses, the matching of H-2 between donor and recipient resulted in early responses of exceptional quality in high-responder strains. It was concluded that under the influence of H-2, whose incompatibility between donor and recipient partially interferes with responses, early but not late primary Thy-1.1-specific antibody responses are selectively controlled by Igh-V or closely linked Ir gene(s) as a new VH marker.

Animals↗
PubMed1984

Ontogeny of the erythrocyte-dependent IgM antibody responses to cell membrane antigens.

Our previous experiments characterized the T-cell independent type 2 B-cell responses to cell membrane antigens that are controlled by two donor cell types with different antigen-presenting (AP) activities. We here report about the ontogeny of this novel type of responses with special reference to the mutual relation of the development among two AP activities and their acceptor functions. The responses of mice to H-2d antigens on allogeneic cells and hapten (fluorescein isothiocyanate) antigens on syngeneic cells were examined in parallel. The positive AP activity displayed by red blood cells (RBC) for induction of anti-hapten responses was fully developed in the fetus, although H-2d antigens on the RBC for induction of anti-H-2d responses was immature in mice under 7 days old. In contrast, the negative AP activity displayed by spleen cells (B cells) for inhibition of the RBC-dependent anti-hapten and anti-H-2d responses was first developed in mice about 3 weeks old. The B cell functions accepting the positive and negative AP activities were also matured by that time. The possible significance of these findings in the physiology and pathology of the unique responses was discussed.

Age Factors↗