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Biomedical subjects

S Taketani

Publications and source records attributed to S Taketani.

At least 109 records · Page 6Linked to original sources
PubMed1994

Increased cell surface expression of a newly identified heterodimer on activated blastic T cells.

A hybridoma (F6C7) was established by fusing NS1 cells with spleen cells of MRL/Mp-+/+ (MRL/+) mice suffering from lpr-GVHD. This F6C7 mAb (IgG2b, kappa) stains a broad spectrum of blood cells at varying intensities in mice and rats. In normal (BALB/c) mice, granulocytes and B cells are highly positive for F6C7-reactive Ag (F6C7-Ag). Thymocytes and peripheral (CD4+ and CD8+) T cells show negative to low intensities. These staining profiles are similar in C57BL/6, AKR/J, C3H/HeJ, and MRL/+ mice. When spleen cells were activated in vitro, a blastic cell population of autoactivated CD4+ and CD8+ T cells showed increased F6C7-Ag expression. Alloactivated CD4+ blastic T cells also showed increased expression of F6C7-Ag, whereas alloactivated CD8+ blastic T cells as well as Con A-activated CD4+ and CD8+ blastic T cells remained at the level of small (nonblastic) cells. These findings suggest that the surface expression of F6C7-Ag is up-regulated in some activation processes of T cells, particularly in autoactivation. Young (2-month-old) MRL/Mp-lpr/lpr (MRL/lpr) mice show staining profiles of F6C7-Ag similar to those of normal mice, except that many more blastic (CD4+ and CD8+) T cells show high F6C7-Ag expression than those of normal mice. A small but significant number of CD4+F6C7-Ag(high) and a much higher number of CD8+F6C7-Ag(high) blastic T cells were observed in the spleen cells of MRL/+ mice suffering from lpr-GVHD. These blastic T cells may exert autoreactivity and participate in the initiation of autoimmune diseases, lymphadenopathy, and lpr-GVHD. Immunoprecipitation and SDS-PAGE revealed that F6C7-Ag is a heterodimer comprised of approximately 78- and 70-kDa molecules without disulfide bonds.

Animals↗
PubMed1994

Functional analysis of thymic B cells.

The expression of low- and high-affinity interleukin-5 receptors (IL-5Rs) on thymic B cells and reactivity of thymic B cells to IL-5 was investigated. Thymic B cells consist of two populations (CD5+ and CD5- B cells), as previously described. Three-color FACS analyses using anti-CD5, anti-IgK, and anti-IL-5R mAbs reveal that approximately 60% of both populations (CD5+ and CD5-) in the thymus possess IL-5R, detected by mAb H-7. In Scatchard plot analyses, IL-5Rs on thymic B cells are observed as low affinity receptors; the high-affinity IL-5R, which is known to be expressed on some IL-5-activated splenic B blasts or some IL-5-dependent cell line cells, is not clearly detected on thymic B cells. The reactivity of thymic B cells to IL-5 is found to be significantly lower than that of splenic B cells both in proliferative responses and LPS-induced IgM and IgA antibody responses. These findings are compatible with the expression of the low-affinity IL-5R on thymic B cells. The responsiveness of thymic B cells to either IL-6 or the combination of IL-4, IL-5 and IL-6 is also lower than that of splenic B cells. Furthermore, the thymic B cells are found to induce neonatal tolerance. Therefore, thymic B cells act as antigen-presenting cells in the negative selection of thymocytes, rather than as antibody-producing cells under the influence of foreign antigens and/or regulatory cytokines.

Animals↗
PubMed1994

Characterization and expression of cDNA encoding coproporphyrinogen oxidase from a patient with hereditary coproporphyria.

Hereditary coproporphyria (HCP) is an acute hepatic porphyria with autosomal dominant inheritance, but with a variable degree of clinical expression. Molecular cloning, sequencing and expression of the defective gene for coproporphyrinogen oxidase (CPO) in a patient with HCP were carried out. Enzyme assays revealed that CPO activity in EBV-transformed lymphoblastoid cells from the proband and one of her sisters was approximately 50% of normal. Nucleotide sequence analysis of CPO cDNAs isolated from the proband's cells demonstrated three base substitutions, and three accompanying amino acid substitutions. An A514-->C transition causing a Asn172-->His substitution occurred in one allele, while two other transitions, G265-->A and G580-->A, caused Gly89-->Ser and Val194-->Ile substitutions, respectively, in the other allele. The A514-->C and the G580-->A transitions are known genetic polymorphisms. Transfection of CPO cDNA into Escherichia coli demonstrated that cDNA with the G265-->A transition produced a protein with less than 5% of normal enzyme activity. These findings indicate that the G265-->A transition, involving the highly conserved glycine residue at the 89th position, is responsible for the CPO defect in the patient and accounts for the partial deficiency of CPO activity in this pedigree.

Amino Acid Sequence↗
PubMed1994

[A successful case of transaortic coronary patch angioplasty for left coronary ostial stenosis in a middle-aged woman].

A 46-year-old woman was admitted to our hospital because of effort angina. Electrocardiogram on exercise showed a significant ST depression in I, II, III, aVF, and V3-6 201Thallium myocardial scintigram demonstrated a low uptake lesion on effort and redistribution in anterior wall of left ventricle. Coronary angiography showed a 50% stenosis only in the left coronary ostium. Operation was carried out by transaortic patch angioplasty using autologous pericardium fixed with 0.25% glutaraldehyde. Her postoperative course was uneventful. Anginal discomfort disappeared, and favorable results was obtained. Recent reports suggest that an isolated coronary ostial stenosis is a distinct clinical entity which is different from the usual atherosclerotic ischemic heart disease. The transaortic patch angioplasty might be useful operative method for the isolated coronary ostial stenosis.

Constriction, Pathologic↗
PubMed1994

A murine nephritogenic monoclonal antibody binds to both single-stranded deoxyribonucleic acid and glomerulus.

BACKGROUND: Autoantibodies such as anti-DNA and antimyeloperoxidase (MPO) antibodies have been shown to cause glomerulonephritis in experimental animal models. To analyze pathogenic autoantibodies, we developed hybridomas from spleen cells of nontreated FGS mice, in which focal segmental glomerular sclerosis develops spontaneously. EXPERIMENTAL DESIGN: Reactivity and specificity of a monoclonal antibody (FG1H5) were examined using enzyme-linked immunosorbent assay and cryosections of mouse organs as substrates. Immunoprecipitation was performed to analyze reactive antigens. Hybridoma cells were injected ip into severe combined immunodeficiency (SCID) mice to examine their nephritogenicity in vivo. RESULTS: The binding of FG1H5 to single-stranded DNA (ssDNA) was inhibited by ssDNA and also MPO. The binding of FG1H5 to MPO was weak, not inhibited by MPO, and markedly enhanced by the presence of ssDNA. This marked enhancement of the binding to MPO was abolished by DNase I-treatment of the mixture of FG1H5 and ssDNA. When MPO was introduced into ssDNA-coated wells, the binding of FG1H5 to ssDNA was inhibited. On the other hand, when ssDNA was introduced into MPO-coated wells, the binding of FG1H5 to MPO was markedly enhanced. Inhibition tests using double-stranded DNA revealed that FG1H5 is specific for ssDNA. Histologic examination of FG1H5-reactive antigen using SCID mouse kidney showed positive stainings in the nucleus and glomerulus (mainly the mesangium). These positive stainings were abolished after the incubation of FG1H5 with ssDNA. The DNase I treatment of kidney sections markedly reduced the nuclear staining, but the staining of the glomerulus was preserved. Immunoprecipitation of a soluble fraction of SCID mouse kidney with FG1H5 revealed that FG1H5-reactive antigen in the glomerulus is an approximately 28-kilodalton molecule. When FG1H5 hybridoma cells were injected ip into SCID mice, the mice showed glomerulonephritis with the increases in mesangial cells and matrix as well as immunoglobulin M deposition mainly in the mesangium. CONCLUSIONS: Data demonstrate that FG1H5 binds strongly and specifically to ssDNA (but weakly and nonspecifically to MPO), and that ssDNA and MPO bind to each other. One monoclonal antibody reacts with both the nucleus and glomerulus (mainly the mesangium), and glomerular staining is not caused by nonspecific DNA binding. FG1H5, which binds to ssDNA, can induce glomerulonephritis, probably because of a direct crossreactivity to glomerular components.

Animals↗
PubMed1994

[A case of coronary artery bypass grafting for single coronary artery complicated by effort angina].

A case of coronary artery bypass grafting (CABG) for single coronary artery (SCA) complicated by effort angina pectoris was reported. A 52-year-old man was admitted complaining of effort angina. Coronary arteriography demonstrated a single coronary artery originated in left coronary sinus bifurcated to the left anterior descending artery (LAD) and the circumflex artery (CX) which extended around the atrio-ventricular fold to send a branch down the posterior small branches extend to posterior surface of the right ventricle. This type single coronary artery was classified to Smith's type I. Other findings included 75% stenosis in LAD #6 and #7, 90% stenosis in CX #11. CABG was carried out using left internal thoracic artery graft and saphenous vein graft. His postoperative course was uneventful. Anginal discomfort disappeared, and favorable results was obtained. SCA might be vulnerable to ischemic insult, so that coronary revascularization should be recommended in selected cases before the onset of serious complications.

Angina Pectoris↗
PubMed1994

[Portal-transfer of an orally administered anti-cancer agent analysis of the time course of portal blood and systemic blood levels of preoperatively administered UFT].

The transfer of an orally administered anti-cancer agent, UFT, into the portal vein was examined in 21 patients with hepatic metastasis of colorectal cancer (synchronous metastasis in 9 and metachronous metastasis in 12 cases) encountered at our department. The time course of tegafur, 5-FU and uracil levels in portal blood was traced for maximum 6 hrs, starting 2 hrs after the final oral dose of UFT. The portal blood tegafur level was 11.89 +/- 4.31 micrograms/ml at 2 hrs after the final dose and decreased gradually thereafter, reaching to 8.48 +/- 8.42 micrograms/ml at 6 hrs after the final dose. Unlike the portal blood tegafur level, the portal blood 5-FU level did not show any similar tendency; it remained almost unchanged at 0.018 +/- 0.006 microgram/ml and approximately equal to the serum 5-FU level throughout the observation period.

Administration, Oral↗
PubMed1993

Coproporphyrinogen oxidase. Purification, molecular cloning, and induction of mRNA during erythroid differentiation.

Coproporphyrinogen oxidase (EC 1.3.3.3), the enzyme involved in the sixth step of heme biosynthesis, was purified to apparent homogeneity from bovine liver; it has a molecular mass of 37,000 daltons. Partial amino acid sequences were determined. Two degenerate oligonucleotides based on the sequences of trypsin-digested peptides were used in a polymerase chain reaction to amplify a 198-base pair fragment of coproporphyrinogen oxidase DNA, using bovine kidney cells cDNA as a starting template. This fragment was used as a hybridization probe to isolate full-length coproporphyrinogen oxidase clones from a mouse erythroleukemia (MEL) cell cDNA library. Sequence analysis revealed that coproporphyrinogen oxidase comprises 354 amino acid residues (M(r) 40,647), with a putative leader sequence of 31 amino acid residues, the result being a mature protein of 323 amino acid residues (M(r) 37,255). RNA blot analysis revealed a 3.0-kilobase coproporphyrinogen oxidase mRNA in mouse liver and in MEL cells. Treatment of MEL cells with dimethyl sulfoxide led to an increase in coproporphyrinogen oxidase mRNA within 10 h, the induction reached a maximum at 24 h, and was in parallel with the induction of ferrochelatase mRNA. The cDNA allows for the expression of active coproporphyrinogen oxidase, the activity of which is mainly present in mitochondria of transfected cultured cells, thereby indicating that mammalian coproporphyrinogen oxidase is mitochondrial enzyme.

Amino Acid Sequence↗
PubMed1993

Cloning and characterization of a 23-kDa stress-induced mouse peritoneal macrophage protein.

Exposure of mouse peritoneal macrophages to oxidative and sulfhydryl-reactive agents in vitro enhances synthesis of a few cellular proteins that may be important in a self-defense system. A cDNA encoding a novel stress-inducible protein, designated MSP23 (macrophage 23-kDa stress protein), was cloned from a cDNA library of the macrophages by differential screening. A 1.0-kilobase mRNA transcript hybridized with the MSP23 cDNA gradually increased in macrophages upon culture in vitro. Treatment with diethylmaleate or glucose/glucose oxidase, which generates H2O2, markedly enhanced the induction of the transcript after several hours. Cadmium chloride and sodium arsenite also induced the transcript. An antiserum raised against recombinant MSP23 reacted with the 23-kDa stress-inducible protein of the macrophages. The amounts of 23-kDa protein in the cells rapidly increased during culture with diethylmaleate. The mRNA was detected in various tissues, and it was especially high in content in the liver. A search of databases revealed that six proteins of various species from bacteria to the mouse have a sequence homology to MSP23. One of the proteins is the C22 component of alkyl hydroperoxide reductase, which is induced by hydrogen peroxide in Salmonella typhimurium.

Amino Acid Sequence↗
PubMed1993

A monoclonal antibody reactive with a glycophosphatidylinositol-anchored molecule on T cells defines CD4+ T cell subsets.

A hybridoma, 25T3 (IgM, kappa), was established from MRL/+ mice immunized with an autoreactive T cell line (l/+T1). The antigenicity of the antigen recognized by hybridoma 25T3 (25T3-Ag) expressed on thymic and splenic cells was abolished by treatment with phosphatidylinositol-specific phospholipase C, showing that 25T3-Ag is a glycophosphatidylinositol-anchored Ag. 25T3-Ag was expressed on approximately 90% of thymocytes. Double-negative, double-positive and CD8 single-positive cells were highly positive for the expression of 25T3-Ag, whereas CD4 single-positive cells were weakly positive (approximately 40%) or negative (approximately 60%). In the spleen, only CD3+ cells (and not B220+ nor Mac-1+ cells) reacted with 25T3 monoclonal antibody (mAb), indicating that 25T3 mAb is specific for T cells. The majority of splenic CD8+ T cells were positive for the expression of 25T3-Ag, although the intensity was weaker than that of thymocytes. In contrast, splenic CD4+ T cells were divided into negative (60-70%) and positive (30-40%) populations. Similar staining profiles were observed in BALB/c, C57BL/6, C3H/HeN and AKR/J mice. When BALB/c CD4+ T cell subsets were sorted and cultured with irradiated (25 Gy) antigen-presenting cells, stimulation with immobilized anti-CD3 mAb for 2 days resulted in CD4+25T3+ cells secreting more interleukin-2 and less interleukin-4 than did CD4+25T3- subsets, although the proliferative responses of the cells on day 2 of culture were similar. This suggests that CD4+ T cells can be divided into two populations and relatively defined as T helper 1 and T helper 2 cells using this 25T3 mAb. Immunoprecipitation and SDS-PAGE revealed that 25T3-Ag was approximately 70 kDa. These findings are discussed in relation to CD4+ T cell subsets.

Animals↗
PubMed1993

Protocadherins: a large family of cadherin-related molecules in central nervous system.

Using the polymerase chain reaction, we have isolated numerous rat and human cDNAs of which the deduced amino acid sequences are highly homologous to the sequences of the extracellular domain of cadherins. The entire putative coding sequences for two human proteins defined by two of these cDNAs have been determined. The overall structure of these molecules is very similar to that of classic cadherins, but they have some unique features. The extracellular domains are composed of six or seven subdomains that are very similar to those of cadherins, but have characteristic properties. The cytoplasmic domains, on the other hand, have no significant homology with those of classic cadherins. Since various cDNAs with almost identical features were obtained also from Xenopus, Drosophila and Caenorhabditis elegans, it appears that similar molecules are expressed in a variety of organisms. We have tentatively named these proteins protocadherins. They are highly expressed in brain and their expression appears to be developmentally regulated. The proteins expressed from the two full-length cDNAs in L cells were approximately 170 or 150 kDa in size, and were localized mainly at cell-cell contact sites. Moreover, the transfectants showed cell adhesion activity.

Amino Acid Sequence↗
PubMed1993

The effect of lead on iron uptake from transferrin in human erythroleukemia (K562) cells.

The effect of lead on cellular iron metabolism has been investigated using human erythroleukemia (K562) cells. When the cells were cultured with 100 microM Pb2+ for 48 h, the rate of cellular iron uptake from transferrin decreased to 46% of that in untreated cells. Scatchard analysis of the binding data revealed that this reduction was the result of a decrease in the number of transferrin receptors rather than an alteration in ligand-receptor affinity. The results of immunoprecipitation of transferrin receptors on the cell surface also confirmed the decreased expression of transferrin receptors by lead-treated cells. The down-regulation of transferrin receptors by treatment with lead did not result from a decrease in the total amount of the receptor, as determined by immunoblotting. Moreover, the biosynthesis of the receptor was unaffected by lead treatment. Thus, the down-regulation of surface transferrin receptors in lead-treated cells might be due to a redistribution of receptors rather than an actual loss of receptors from the cell. Using kinetic analysis, it was shown that redistribution of the receptor did not result from the alteration in the rates of transferrin receptor recycling. A comparison of the amounts of transferrin receptor on the cell surface and in the cycling pool revealed that the sequestration of the receptor from normal flow through the cycle might cause down-regulation of the surface receptor.

Biological Transport↗
PubMed1993

Molecular defect in human erythropoietic protoporphyria with fatal liver failure.

We investigated the molecular basis of ferrochelatase in a Japanese patient with erythropoietic protoporphyria (EPP), complicated by fatal liver failure, and defined a novel point mutation in the ferrochelatase gene. cDNAs were synthesized using Epstein-Barr-virus-transformed lymphoblastoid cells from the proband. cDNA clones encoding ferrochelatase in the proband were isolated by amplification using the polymerase chain reaction. There were two sizes of ferrochelatase cDNAs; one was normal in size, the other being smaller. Sequence analysis of the abnormally sized cDNA clones revealed that they lacked exon 9 of the ferrochelatase gene. Genomic DNA analysis demonstrated that the proband had the abnormal allele and that it contained a G to A point mutation at the first position of the donor site of intron 9. An identical mutation was detected in the affected family members of the proband by allele-specific oligonucleotide hybridization analysis. EPP is inherited in an autosomal dominant manner in this family.

Adult↗
PubMed1993

Haem is necessary for a continued increase in ferrochelatase mRNA in murine erythroleukaemia cells during erythroid differentiation.

The level of mRNA encoding ferrochelatase (FeC) was examined in two murine erythroleukaemia (MEL) clones, DS and DR, a DMSO-sensitive, and a DMSO-resistant clone, respectively. DS cells undergo erythroid differentiation by DMSO treatment with a marked increase in haem synthesis, while DR cells fail to do so due to the lack of the erythroid-specific delta-aminolaevulinate synthase (ALAS-E). Both DS and DR cells showed an increase in the level of FeC mRNA within 18 h of DMSO treatment. The level of FeC mRNA in DR cells was then decreased, while that in DS cells continued to increase for 72 h. Treatment with haemin significantly increased FeC mRNA in DR cells. When cells were treated with both DMSO and haemin, the level of FeC mRNA in DR cells increased to a level comparable to that in DS cells. These findings suggest that the failure to maintain increased FeC mRNA DR cells after DMSO treatment may be due to a deficiency of haem in these cells.

Animals↗
PubMed1993

Dimethyl sulphoxide and haemin induce ferrochelatase mRNA by different mechanisms in murine erythroleukaemia cells.

The level of mRNA encoding ferrochelatase (FeC), the terminal enzyme of the haem biosynthetic pathway, was examined in murine erythroleukaemia (MEL) cells when they were induced to undergo erythroid cell differentiation by treatment with dimethyl sulphoxide (DMSO), or haemin. FeC mRNA increased within 12 h after DMSO or haemin treatment of MEL cells, and its level continued to increase for 48 h. Treatment of cells with succinylacetone (SA), a potent inhibitor of haem synthesis, suppressed a DMSO-mediated increase in FeC mRNA, and haemin treatment reversed a SA-mediated decrease in FeC mRNA. Nuclear runoff analyses showed that, while DMSO increased the rate of transcription of FeC mRNA, haemin did not. These results indicate that the induction of FeC mRNA by DMSO is largely transcriptional, while that by haemin is post-transcriptional.

Animals↗