Biomedical subjects

T Imai

Publications and source records attributed to T Imai.

At least 451 records · Page 25Linked to original sources

PubMed1996

[Inhaled corticosteroid therapy in long-term management of adult asthma].

Bronchial asthma is no longer considered a condition with isolated, acute episodes of bronchoconstriction. Rather, asthma is now understood to be a chronic inflammatory disorder of the airways. Therefore anti-inflammatory agents and, more specifically, inhaled corticosteroids are at present the most effective controllers in long-term treatment and prevention of asthma. Asthma is highly variable, so precise classification of severity is needed for management. Asthma therapy recommended in guidelines follows a stepwise approach in which the level of therapy is increased (step up) as the severity of asthma increased and therapy decreased (step down) once control is achieved and sustained. In this stepwise approach, inhaled corticosteroid is a key drug and establishment of the dosage of inhaled corticosteroid is most important.

Administration, Inhalation↗

PubMed1996

[Evaluation of efficacy for Japanese cedar pollen-specific immunotherapy by lymphocyte proliferation test].

Peripheral mononuclear cells from 47 patients suffering from Japanese cedar pollinosis were stimulated with crude pollen extract of Cryptomeria Japonica (CJ) to evaluate the effect of CJ-specific immunotherapy. The stimulation index (SI) with crude pollen extract of CJ in the patients with excellent and good clinical outcome was significantly lower than those with poor outcome. The SI increased with the increasing symptoms in a dose dependent manner. In the patients under immunotherapy for long period, the good clinical outcome and low SI were gained. These results suggest that peripheral lymphocyte proliferation test should be a good objective indicator for allergen-specific immunotherapy.

Adult↗

PubMed1996

[Studies on changes in the ratio of free to total PSA after endocrine treatment of prostate carcinoma].

The post-diagnostic changes in the free to total PSA ratio in the serum of patients with prostate carcinoma, after the initiation of endocrine treatment were examined. Two-week pretreatment with either chlormadinone acetate (100 mg/day) or flutamide (375 ng/day) was administered orally to 14 patients with newly diagnosed advanced prostate carcinoma (clinical stage was C in 2, Dl in 1 and D2 in 11). Then the LH-RH analogue was injected. Total and free PSA in the serum of these patients were measured every 4 weeks by the Ab bead PSA (Eiken) and the recently developed assay for free PSA by Eiken, respectively. The follow-up period ranged from 3 to 9 months with a median of 6 months. Levels of both total and free PSAs decreased significantly following the endocrine treatment, while free to total PSA ratio at 4 to 16 weeks after the start of LH-RH analogue was increased significantly compared to the pretreatment level (p < 0.05). These findings suggest that the rate of decrease of complex PSA during the first 4 months after the beginning of treatment may exceed that of free PSA in the serum of patients with advanced prostate carcinoma initially treated with endocrine therapy.

Aged↗

PubMed1995

Expression and localization of glucose transporter 1 (GLUT1) in the rat oviduct: a possible supplier of glucose to embryo during early embryonic development.

The oviduct fluid mainly derived from the oviduct epithelium is reported to provide the environment necessary for embryonic development. To elucidate the origin of glucose in the oviduct fluid, we examined the expression and localization of glucose transporter 1 (GLUT1) in the rat oviduct by Northern blot analysis, immunoblot analysis and immunohistochemistry using both light and electron microscopy. Northern blot and immunoblot analyses both showed the presence of the GLUT1 mRNA and protein. Specific staining for GLUT1 was observed in the ampulla and the isthmus, but only slightly in the fimbria and the utero-tubal junction. Staining was confined to the luminal surface of the epithelial mucosa. Immunoelectron microscopic analysis revealed that GLUT1 was observed only on the surface of the microvilli in non ciliated secretory cells, but not in ciliated cells. These findings suggest that GLUT1 plays an important role in the glucose transfer from the oviduct epithelium into the lumen and in maintaining the adequate glucose concentration of the oviduct fluid for embryonic development in rat oviduct.

Animals↗

PubMed1995

Exon skipping caused by a base substitution at a splice site in the GTP cyclohydrolase I gene in a Japanese family with hereditary progressive dystonia dopa responsive dystonia.

We report a novel mutation at a splice site in the GTP cyclohydrolase I gene in a Japanese family with hereditary progressive dystonia with marked diurnal fluctuation (HPD)/dopa responsive dystonia (DRD). Reverse transcriptase-initiated PCR (RT-PCR) of lymphocyte mRNA showed both normal and small size fragments in the HPD patient and his asymptomatic mother. Sequence analysis revealed that skip splicing of exon 1 to exon 3 occurred in the small fragment. The patient and his mother were heterozygous for G --> C substitution at conserved consensus sequence GT at 5' end of the intron 2. Quantitative RT-PCR showed that the expression of normal GTP cyclohydrolase I mRNA decreased in their lymphocytes, while the HPD patient had more expression of mutant GTP cyclohydrolase I mRNA than his asymptomatic mother.

Adult↗

PubMed1995

Interferon-alpha-induced protection of renal cell cancer cell line from lysis by natural killer cells and increase of susceptibility by treatment with 5-fluorouracil.

We have shown previously that interferon (IFN)-alpha reduces the sensitivity of renal cell cancer (RCC) cell lines ACHN and KRC/Y to lysis by lymphokine-activated killer (LAK) cells. The close relationship between natural killer (NK) cells and LAK cells prompted us to investigate whether IFN-alpha pretreatment also affects the sensitivity of ACHN cells to lysis by NK cells or IFN-alpha-activated NK cells. A 51Cr-release cytotoxicity assay demonstrated that pretreatment of ACHN with IFN-alpha decreased their susceptibility to NK cells and IFN-alpha-activated NK cells in a dose-dependent manner. Moreover, to investigate the usefulness of 5-fluorouracil (5FU) for combination with IFN-alpha therapy, we examined the effect of preincubation with 5FU on the susceptibility of ACHN. IFN-alpha-induced protection of ACHN from lysis by IFN-alpha-activated NK cells weakened in the presence of 5FU at 0.2 microgram/ml. An adhesion assay showed that preincubation of ACHN with 5FU and IFN-alpha did not alter the adhesion of IFN-alpha-activated NK cells. A cold target competition analysis did not show any difference between untreated and 5FU and/or IFN-alpha-treated competitors. These results suggest that one of the mechanisms of 5FU for combination with IFN-alpha therapy might depend on changes of RCC cells in intrinsic lysability involving a post-binding stage of the lytic cycle to NK cells.

Carcinoma, Renal Cell↗

PubMed1995

Molecular analyses of the association of CD4 with two members of the transmembrane 4 superfamily, CD81 and CD82.

Previously, we have shown that CD81 and CD82, two members of the transmembrane 4 superfamily, form multimolecular membrane complexes by associating with each other and with CD4 or CD8 in T cells. In the present study, we further analyzed the molecular basis of the CD4 association with CD81 and CD82 by co-precipitation experiments. First, we examined the regions of CD4 involved in the association with CD81 and CD82 by employing chimeric proteins generated from CD4 and CD2. It was confirmed that CD4, but not CD2, was capable of binding with CD81 and CD82 in transfected cells. We found that the cytoplasmic region of CD4 was sufficient for the chimeric proteins to co-precipitate CD81, while both the cytoplasmic and extracellular regions of CD4 were required for them to efficiently co-precipitate CD82. We next found, by using truncated CD4 lacking the C-terminal 31 amino acids or mutated CD4 with the cysteine residues at 394 and 397 replaced by serine, that the p56lck binding site or the covalent modification with palmitic acid was not necessary for CD4 to associate with CD81 and CD82. Finally, we found that the binding of p56lck to CD4 strongly inhibited its association with CD81 and CD82. It is, therefore, suggested that CD4 exists at least in two physical states, one associated with p56lck and another associated with CD81 and CD82 in the absence or uncoupling of p56lck.

Acylation↗

PubMed1995

Alternative splicing and genomic structure of the AML1 gene involved in acute myeloid leukemia.

We previously isolated the AML1 gene, which is rearranged by the t(8;21) translocation in acute myeloid leukemia. The AML1 gene is highly homologous to the Drosophila segmentation gene runt and the mouse transcription factor PEBP2 alpha subunit gene. This region of homology, called the Runt domain, is responsible for DNA-binding and protein--protein interaction. In this study, we isolated and characterized various forms of AML1 cDNAs which reflect a complex pattern of mRNA species. Analysis of these cDNAs has led to the identification of two distinct AML1 proteins, designated AML1b (453 amino acids) and AML1c (480 amino acids), which differ markedly from the previously reported AML1a (250 amino acids) with regard to their C-terminal regions, although all three contain the Runt domain. The large C-terminal region common to AML1b and AML1c is suggested to be a transcriptional activation domain. AML1c differs from AML1b by only 32 amino acids in the N-terminal. Characterization of the genomic structure revealed that the AML1 gene consists of nine exons and spans > 150 kb of genomic DNA. Northern blot analysis demonstrated the presence of six major transcripts, encoding AML1b or AML1c, which can all be explained by the existence of two promoters, alternative splicing and differential usage of three polyadenylation sites. A minor transcript encoding AML1a which results from alternative splicing of a separate exon can be detected only by reverse transcription-polymerase chain reaction amplification. The distinct proteins encoded by the AML1 gene may have different functions, which could contribute to regulating cell growth and/or differentiation through transcriptional regulation of a specific subset of target genes.

Alternative Splicing↗

PubMed1995

A novel 6Fe (2 x [3Fe-4S]) ferredoxin from Mycobacterium smegmatis.

A novel ferredoxin was purified from Mycobacterium smegmatis by a series of hydrophobic chromatographies in the presence of high concentrations of ammonium sulfate and sodium chloride. The ferredoxin exhibited the same peptide map and N-terminal amino acid sequence as the known 7Fe ferredoxin from the same bacterium. On the other hand, this ferredoxin was found to contain approximately 6 Fe/mol ferredoxin and was also shown to contain only [3Fe-4S] clusters by resonance Raman spectroscopy, indicating that it is a novel 6Fe ferredoxin which contains two [3Fe-4S] clusters.

Electron Spin Resonance Spectroscopy↗

PubMed1995

Construction of YAC contigs at human chromosome 11q22.3-q23.1 region covering the Ataxia telangiectasia locus.

Ataxia telangiectasia (AT) is an autosomal recessive disease of unknown etiology associated with cerebellar ataxia, telangiectasia, immune dysfunction, higher cancer risk, genomic instability and hypersensitivity to ionizing radiation. The major AT loci, AT-A and AT-C, are shown to be closely linked at chromosome 11q22-q23. The most recent genetic linkage mapping and linkage disequilibrium analysis have localized the major AT loci to a sequence of approximately 850 kb between the markers D11S1819 and D11S1818. The isolation of yeast artificial chromosomes spanning the AT region is an essential step to identify the gene or genes responsible for the mutation(s). We isolated a total of 20 YAC clones from three independent YAC libraries, using sequence tagged sites mapped in the AT region as primers for PCR-based YAC screening. The PCR assay for the presence or absence of 16 different DNA markers allowed us to construct and to order four YAC contigs at the AT region. One of the contigs which consists of the 10 YAC clones, covers about 2 Mb of DNA at the boundary between Giemsa-positive band 11q22.3 and Giemsa-negative band 11q23.1 and includes the entire region of the major AT locus between D11S1819 and D11S1818. Thus, the YAC contigs will facilitate the positional cloning approach for searching transcribed sequences from the defined genomic region.

Ataxia Telangiectasia↗

PubMed1995

Identification of a highly specific surface marker of T-cell acute lymphoblastic leukemia and neuroblastoma as a new member of the transmembrane 4 superfamily.

Five monoclonal antibodies detected a surface antigen expressed exclusively on T-cell acute lymphoblastic leukemia (T-ALL) in a panel of 45 human hematopoietic cell lines, including T-cell lines derived from adult T-cell leukemia and those established by immortalization with human T-cell leukemia virus type 1 or Herpesvirus saimiri. Peripheral blood mononuclear cells, including fresh and activated T cells, were also completely devoid of this antigen. We designated this antigen as TALLA-1 (from T-ALL-associated antigen 1). By expression cloning, a cDNA clone encoding TALLA-1 was isolated from T-ALL cell line Molt-4. TALLA-1 was found to be a member of the transmembrane 4 superfamily (TM4SF). The cDNA was also essentially identical to A15, which was isolated from another T-ALL cell line, HPB-ALL, by differential hybridization with normal peripheral blood lymphocytes, and to CCG-B7, which was isolated from a brain cDNA library using CCG repeat as a probe. The gene product was now characterized in detail at the protein level. Northern blot analysis showed that the gene was expressed most strongly in brain, skeletal muscle and spleen. In a panel of 52 non-hematopoietic human cell lines, the majority of neuroblastoma cell lines were found to be positive for TALLA-1. Like ME491, CO-029 and L6, TALLA-1 may be another TM4SF member behaving as a potential tumor-associated antigen.

Amino Acid Sequence↗

PubMed1995

Silk gland factor-1 involved in the regulation of Bombyx sericin-1 gene contains fork head motif.

Silk gland factor-1 (SGF-1) regulates transcription of the Bombyx sericin-1 gene via interaction with the SA site. In this study, two related SGF-1 polypeptides of apparent molecular masses of 40 and 41 kDa were purified. Specific interaction of these proteins with the SA site was demonstrated by electrophoretic mobility shift and dimethyl sulfate methylation interference assays. The SGF-1 40-kDa protein was partially sequenced and characterized as a new member of the fork head/HNF-3 family. Several full-length cDNAs encoding the SGF-1 40-kDa and possibly also the 41-kDa proteins were cloned and sequenced. SGF-1 mRNA is expressed consistently with the presumed role of the SGF-1 protein product in regulating the sericin-1 gene. The SGF-1 protein contains putative transactivation domains. We conclude that the 40- and 41-kDa SGF-1 proteins affect transcription of the sericin-1 gene via binding to the SA site.

Amino Acid Sequence↗

PubMed1995

Opposite effects of transforming growth factor alpha and epidermal growth factor on mouse placental lactogen I secretion.

This study was undertaken to determine whether transforming growth factor alpha (TGF-alpha) regulates the production of mouse placental lactogen I (mPL-I) and mPL-II in a manner that is similar to that of epidermal growth factor (EGF), which was previously shown to stimulate mPL-I secretion and inhibit mPL-II secretion. In contrast to the activity of EGF, human (h) and rat (r) TGF-alpha (each at 100 ng/ml) inhibited secretion of mPL-I by placental cells isolated from mice on day 7 of pregnancy. Maximum inhibition of mPL-I secretion occurred on the third day of a 5-day culture period and ranged between 37% and 56% in multiple trials. Incubation of cells with hTGF-alpha and EGF was not followed by a change in the mPL-I concentration of the medium, suggesting the peptides antagonized each other's effects. hTGF-alpha and rTGF-alpha inhibited secretion of mPL-II; maximum inhibition ranged between 62% and 84% in multiple trials. The lowest concentrations of hTGF-alpha that affected mPL-I and mPL-II secretion were 10 ng/ml and 1 ng/ml, respectively. EGF and hTGF-alpha bound to the same receptors on placental cells, as assessed by cross-linking, and both peptides stimulated receptor phosphorylation, as assessed by Western blot analysis. There are three types of mPL-containing cells in placental cultures: cells that contain only mPL-I, cells that contain only mPL-II, and cells that contain both mPLs. The percentage of each type of mPL-containing cell in the culture was determined by immunostaining. hTGF-alpha affected the differentiation of the subpopulations of PL-containing cells in a manner that differed from that of EGF. The data suggest that TGF-alpha and EGF do not regulate the production of mPL-I and mPL-II in a similar manner.

Animals↗

PubMed1995

Molecular cloning of a novel C or gamma type chemokine, SCM-1.

From human PBMC stimulated with PHA, we have isolated cDNA clones encoding a novel cytokine named SCM-1, which is significantly related to the CC and the CXC chemokines but has only the 2nd and the 4th of the four cysteines conserved in these proteins. Its gene is also distinctly mapped to human chromosome 1. SCM-1 is strongly induced in human PBMC and Jurkat T cells by PHA stimulation. Among various human tissues, SCM-1 is expressed most strongly in spleen. SCM-1 is found to be 60.5% identical to lymphotactin, a recently described murine lymphocyte-specific chemokine, which also retains only two cysteines. SCM-1 and lymphotactin may thus represent the human and murine prototypes of a novel C or gamma type chemokine family.

Amino Acid Sequence↗

PubMed1995

Existence of branched side chains in the cell wall mannan of pathogenic yeast, Candida albicans. Structure-antigenicity relationship between the cell wall mannans of Candida albicans and Candida parapsilosis.

Isolation of side chain oligosaccharides from mannans of Candida albicans NIH B-792 (serotype B) and Candida parapsilosis IFO 1396 strains has been conducted by acetolysis under mild conditions. Structural study of these oligosaccharides by 1H and 13C NMR and methylation analyses indicated the presence of novel branched side chains with the following structures in C. albicans mannan. [sequence: see text] It was observed that the H-1 proton chemical shifts of the second and the third mannose units from the reducing terminus in each oligosaccharide are shifted upfield by substitution with an alpha-linked mannose unit at position 6 of the 3-O-substituted mannose unit. An agglutination inhibition assay between factor 4 serum and cells of Candida stellatoidea IFO 1397 lacking the beta-1,2-linked mannose unit, with oligosaccharides obtained from these mannans, indicated that only the branched oligosaccharides were active. This finding suggests that the branched oligosaccharides correspond to the epitope of antigenic factor 4. The presence of the branched structure in other mannans was detected by the characteristic H-1-H-2-correlated cross-peak of the alpha-1,2-linked mannose unit connected with the 3,6-di-O-substituted one by two-dimensional homonuclear Hartmann-Hahn spectroscopy.

Acids↗

PubMed1995

Mycobacterium smegmatis malate dehydrogenase: activation of the lipid-depleted enzyme by anionic phospholipids and phosphatidylethanolamine.

Phospholipid-protein interactions have been investigated in a phospholipid-requiring enzyme, FAD-dependent malate dehydrogenase isolated from Mycobacterium smegmatis membranes, to correlate these interactions with enzyme function. The ability of several natural and synthetic phospholipids including CL and PE, which are major phospholipids in M. smegmatis membranes, to activate purified, lipid-depleted, enzymatically inactive malate dehydrogenase was examined. Anionic phospholipids and PE activated the enzyme, while zwitterionic phospholipids did not. A PE/PC mixture activated the enzyme in the form of both bilayer and non-bilayer structure. CL/PE mixtures activated malate dehydrogenase much more than each single phospholipid species. All anionic phospholipids used stabilized the enzyme, while PE and zwitterionic phospholipids did not. CL and a CL/PE mixture protected malate dehydrogenase from proteinase digestion, while PE did not. All phospholipids and phospholipid mixtures tested caused little secondary structural change in malate dehydrogenase. The results obtained in this study suggest that CL and CL/PE mixtures could form stable, enzymatically active complexes with malate dehydrogenase which might be similar to the native complex in M. smegmatis membranes. Although PE could activate malate dehydrogenase in both bilayer and non-bilayer form, it formed a complex with malate dehydrogenase which was inferior in terms of stability and susceptibility to proteinases, indicating that PE alone poorly reconstitutes the active enzyme-phospholipid complex.

Enzyme Activation↗

PubMed1995

Measurement of yeast intracellular pH by image processing and the change it undergoes during growth phase.

The intracellular pH of the yeast Saccharomyces cerevisiae was determined by a fluorescence microscopic image processing technique. Image processing was carried out using a modification of the ratio imaging method for measurement of yeast intracellular pH. Care was necessary when taking fluorescence images in order to obtain accurate measurement of yeast intracellular pH. Until now it has been difficult to measure the intracellular pH of cells in actual cultivation conditions. This method enabled us not only to measure the intracellular pH of dilute cell suspensions, but also to obtain two-dimensional information. In the case of resting cells, the intracellular pH was dependent upon the extracellular pH, and this value was constant when the extracellular pH was constant. On the other hand, in the case of actively growing cells, intracellular pH was found to change, even if the extracellular pH was constant: the values observed were intracellular pH 5.7 during lag phase, intracellular pH 6.8 during exponential phase and intracellular pH 5.5 during stationary phase. These results for intracellular pH indicate that the yeast proton pump was activated during growth from the point of view of pH in vivo.

Ammonia↗

PubMed1995

Allelic losses on chromosome band 11q13 in aldosterone-producing adrenal tumors.

We examined loss of heterozygosity (LOH) in 14 aldosterone-producing adrenal tumors, with six linearly ordered restriction fragment length polymorphism (RFLP) markers that map within a 12-cM region containing the MEN1 locus on 11q13. Among 11 tumors that were informative for at least one marker, five showed LOH at one or more loci, and two distinct regions of deletion were identified. The proximal region overlapped with the location of the MEN1 locus previously predicted by linkage analyses in MEN1 families and the commonly deleted region in hyperparathyroid tumors. This suggests that one of the genes associated with development of aldosterone-producing adrenal tumors may coincide with the MEN1 locus, and that a second gene, distal to the MEN1 locus, may also play a role in the development of this type of tumor.

Adrenal Gland Neoplasms↗