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Y Ichikawa

Publications and source records attributed to Y Ichikawa.

At least 433 records · Page 24Linked to original sources
PubMed1992

Enzyme-catalyzed oligosaccharide synthesis.

Cell-surface carbohydrates and their conjugates are involved in many types of molecular recognition. This review describes recent developments in enzyme-catalyzed oligosaccharide synthesis, with particular focus on glycosyltransferase and glycosidase reactions. With the increasing availability of glycosyltransferases via recombinant DNA technology, glycosyltransferase-catalyzed glycosylation with in situ regeneration of sugar nucleotides appears to be the most effective method for large-scale stereocontrolled oligosaccharide synthesis.

Carbohydrate Sequence↗
PubMed1992

Expression cloning of a sheep adreno-ferredoxin using the polymerase chain reaction.

In addition to the selective amplification of cDNA from total RNA by the PCR method, the distinctive properties of ferredoxin-expressing colonies can be used for cloning a ferredoxin cDNA. This strategy for cloning and expressing cDNA in E. coli was applied to a sheep adreno-ferredoxin. The expressed sheep ferredoxin showed a spectral pattern typical of [2Fe-2S] proteins. The amino acid sequence deduced from the DNA sequence showed that the mature form of sheep ferredoxin consists of 128 amino acid residues. This rapid and simple method for cloning and expressing cDNA can be applied to other ferredoxins.

Adrenal Cortex↗
PubMed1992

Genetic factors and suppression of metastatic ability of v-Ha-ras-transfected rat mammary cancer cells.

Following v-Ha-ras transfection of nonmetastatic dimethylbenz(( a ))anthracene-induced rat mammary cancer (RMC1) cells, occasional transfectants were isolated that acquired high metastatic ability. High metastatic ability is not a simple process regulated by v-Ha-ras p21 levels alone in these v-Ha-ras transfectants but involves the development of cytogenetic changes. If such cytogenetic changes involve only gain in gene expression, then all hybrids formed by fusing highly metastatic v-Ha-ras RMC1 transfectants with the parental nonmetastatic RMC1 should be highly metastatic. If loss of a metastatic suppressor gene(s) is also involved, then such hybrids should be nonmetastatic since chromosomes from the nonmetastatic parental cells should supply the suppressor function. To test this possibility, a highly metastatic cloned v-Ha-ras transfectant was fused with the nonmetastatic parental RMC1 cells. Five hybrid clones were isolated that conserved the chromosomes from their parental cells. When these hybrid clones were injected into animals, primary tumors developed with the same tumor-doubling time as that of the highly metastatic parental v-Ha-ras transfectant (i.e., approximately 2 days). High metastatic ability was, however, suppressed in these hybrid clones. All hybrid clones continued to express v-Ha-ras p21. Thus, suppression of metastatic ability in the hybrids can occur even in the presence of an elevated v-Ha-ras p21 level. This suggests that the acquisition of metastatic ability following v-Ha-ras transfection involves loss of metastasis suppressor gene function in rat mammary cancer cells.

Animals↗
PubMed1992

Role of steroid 11 beta-hydroxylase and steroid 18-hydroxylase in the biosynthesis of glucocorticoids and mineralocorticoids in humans.

A gene encoding steroid 18-hydroxylase (P-450C18) was isolated from a human genomic DNA library. It was identified as CYP11B2, which was previously postulated to be a pseudogene or a less active gene closely related to CYP11B1, the gene encoding steroid 11 beta-hydroxylase (P-45011 beta) [Mornet, E., Dupont, J., Vitek, A. & White, P. C. (1989) J. Biol. Chem. 264, 20961-20967]. The nucleotide sequence of the promoter region of the P-450C18 gene is strikingly different from that of the P-45011 beta gene, although the sequences of their exons are 93% identical. The transient expression in Y-1 adrenal tumor cells of CAT constructs with a series of deletion mutants of promoter regions of both genes indicated that the two genes are regulated differently. P-450C18 as expressed in COS-7 cells exhibits steroid 18-hydroxylase activity to catalyze the synthesis of aldosterone and 18-oxocortisol and exhibits steroid 11 beta-hydroxylase activity as well. In contrast, P-45011 beta as expressed in the cultured cells exhibits steroid 11 beta-hydroxylase activity exclusively but fails to catalyze the synthesis of aldosterone and 18-oxocortisol. These results indicate that P-45011 beta and P-450C18 are products of two different genes and that the former participates in the synthesis of glucocorticoids whereas the latter participates in the synthesis of mineralocorticoids in humans.

Amino Acid Sequence↗
PubMed1992

Immunohistological analysis in the distribution of cells in the fetal porcine adenohypophysis.

Adenohypophyses of porcine fetuses from 25 to 110 days of gestation were studied by immunohistochemical staining to ascertain the ontogeny of specific cell types and their spatial distribution in the pars distalis. No hormone-containing cells were found before 30 days of gestation. ACTH cells were observed first at 40 days, while GH and LH cells appeared first at 60 days. PRL cells were initially detected at 105 days. ACTH immunoreactive cells were also observed in the pars intermedia at 40 days. Blood capillaries were interposed between cell cords of the pars distalis after 40 days of gestation. ACTH cells were evenly distribution in all areas of the pars distalis except the rostral area (sex zone). GH cells were densely distributed in lateral wings of the pars distalis and immediately anterior to Rathke's lumen. PRL cells resembled GH cells in their distribution pattern, but PRL cells were fewer in number. LH cells were scattered in the sex zone of the pars distalis from 60 to 80 days of gestation. After 90 days, they became scattered throughout the pars distalis but were more numerous in the sex zone than in other areas. The inductive elements of adenohypophysial cells from Rathke's pouch epithelia are discussed. We hypothesize that cell cords of specific areas facing Rathke's lumen may differentiate into specific cell types of the pars distalis during fetal life.

Adrenocorticotropic Hormone↗
PubMed1992

Cross-reactivity of highly purified okadaic acid (OA), synthetic, spiroketal East sphere of OA and ciguatoxin.

This study presents data from the cross-reactivity analysis of purified ciguatoxin (CTX), okadaic acid (OA), and the East sphere or Fragment B-C of OA with their homologous antibodies, monoclonal antibodies to ciguatoxin (MAb-CTX) and okadaic acid (MAb-OA). The test system used was the stick enzyme immunoassay. MAb-CTX gave peak titers of 1.5ng, 10ng and 50ng respectively for CTX, East sphere and OA. Competitive inhibition analysis showed that 4ng purified CTX blocked completely MAb-CTX reaction with crude CTX, OA and East sphere of OA blocked at similar concentrations (approximately 50ng). The activity with MAb-OA in the homologous system with OA and East sphere was insignificant. This may be attributable to the improper concentrations used. The cross-reactivity between MAb-CTX with OA and its Fragment B-C may cause difficulty in the test system in its application to assess toxic fish due to ciguatoxin.

Animals↗
PubMed1992

Early diagnosis of kidney transplant rejection and cyclosporin nephrotoxicity by urine cytology.

A total of 2000 urine samples from 53 kidney transplant recipients were studied to develop a routine method for the early diagnosis of rejection and cyclosporin (CSA) nephrotoxicity in urine. New-Sternheimer staining and an immunocytochemical technique were used together with classical Papanicolaou staining to differentiate cells in the urine. After cell count and differentiation of second morning urine samples with New-Sternheimer and Papanicolaou stains, immunocytochemistry was performed using antibodies against the following antigens: CD2, CD4, CD8, CD25, CD71 (transferrin receptor), HLA-DR and cytokeratin (Lu-5). Cell counts were obtained for the positively-reacting cells per millilitre of urine. By New-Sternheimer and Papanicolaou staining, CSA nephrotoxicity was characterized by the predominance of proximal tubular cells. During rejection episodes, increased numbers of mononuclear cells and renal epithelial cells were found. Immunocytochemical analysis showed a significant increase in CD2-, CD4-, CD8-, CD25-, CD71-, and HLA-DR-positive epithelial cells and in the ratio HLA-DR/cytokeratin-positive epithelial cells in rejection. CD25-positive cells had the highest sensitivity and specificity for the diagnosis of rejection. Our urine cytology technique proved to be a useful and non-invasive method for the early diagnosis of rejection and CSA nephrotoxicity.

Adolescent↗
PubMed1992

Analysis of the transcripts of cytochrome P-450IID gene subfamily in bovine adrenal gland.

An in situ hybridization experiment showed that the gene transcripts of P-450IID subfamily were uniformly distributed in bovine liver cells and at low levels in bovine adrenal cortex and medulla. There was no clear localization of transcripts of P-450IID genes in three adrenocortical zones, zona glomerulosa, zona fasciculata and zona reticularis. The intensity of signal obtained in the adrenal cortex and medulla showed approximately 2.5:1 ratio. The presence of gene transcripts of P-450IID subfamily in adrenocortex was confirmed by amplifying cDNA using PCR and hybridizing the PCR products with P-450IID cDNA.

Adrenal Glands↗
PubMed1992

Selective chemical modification of amino acid residues in the flavin adenine dinucleotide binding site of NADPH-ferredoxin reductase.

1. An apo-NADPH-ferredoxin reductase was prepared from holo-NADPH-ferredoxin reductase (EC 1.18.1.2) from bovine adrenocortical mitochondria. 2. Amino acid residues of the apo-reductase were modified selectively, to identify the FAD-binding site of the reductase, with chemical reagents such as diethylpyrocarbonate, 5,5'-dithiobis(2-nitrobenzoate), tetranitromethane, pyridoxal 5'-phosphate, p-nitrophenylglyoxal, diisopropylfluorophosphate and N-bromosuccinimide. The binding of FAD to the apo-reductase was measured as quenching of the fluorescence of FAD caused by the binding between apo-reductase and FAD. The quenching was blocked when the apo-reductase was modified with diethylpyrocarbonate and restored on the addition of hydroxylamine. 3. The blocking of the quenching occurred in a competitive manner as to FAD in the presence of diethylpyrocarbonate. However, when the apo-reductase was modified with 5,5'-dithiobis(2-nitrobenzoate), the blocking of the quenching occurred in a non-competitive manner. 4. These results suggested that a histidyl residue of the apo-reductase is essential for the binding of FAD to the reductase. This was confirmed by amino acid sequencing of the modified apo-reductase.

Amino Acid Sequence↗
PubMed1992

Determination of the amino acid sequence of adreno-ferredoxin from sheep adrenocortical mitochondria.

1. An adreno-ferredoxin was purified from sheep adrenocortical mitochondria. 2. Its amino acid composition and amino acid sequence were determined chemically. 3. It was found to be composed of 127 amino acid residues, including two tyrosyl residues. 4. The amino acid sequences of various ferredoxins of the two iron and two sulfur type were compared with respect to amino acid homology.

Adrenal Cortex↗
PubMed1992

Molecular cloning and nucleotide sequences of bovine hepato-ferredoxin cDNA; identical primary structures of hepato- and adreno-ferredoxins.

1. The ferredoxin from bovine liver mitochondria, so-called hepatoredoxin, was purified and characterized as to its molecular weight, optical absorption spectrum and amino acid composition. 2. These properties were found to be very similar to those of adreno-ferredoxin. 3. To clarify the molecular basis of tissue specificity, the ferredoxin clones were obtained from a bovine liver library and the cDNA sequence of hepato-ferredoxin was determined. 4. The nucleotide sequence of hepato-ferredoxin clone was found to be identical to that of adreno-ferredoxin clone except for a single nucleotide in the 3' non-translated region. 5. Identical amino acid sequence of the two ferredoxins was confirmed by determining the partial amino acid sequence of the purified hepato-ferredoxin. 6. The results indicated that the organ specific activity of purified ferredoxin could not be explained by the different primary structure nor different RNA processing. 7. Other factors may be involved in the tissue specific properties of ferredoxins.

Adrenal Glands↗
PubMed1992

Tissue compatibility and stability of a new zirconia ceramic in vivo.

Tissue reaction and stability of partially stabilized zirconia ceramic in vivo was evaluated with the use of the subcutaneous implantation test. During the experimental period, zirconia ceramic was completely encapsulated by a thin fibrous connective tissue with less than 80 microns thickness. No changes of weight and 3-point bending strength were detected after 12 months of implantation. The result suggests that zirconia ceramic is biocompatible and no degradation of zirconia ceramic occurred.

Aluminum Oxide↗
PubMed1992

Two-color flow cytometric analysis of thymic lymphocytes from patients with myasthenia gravis and/or thymoma.

Phenotypic characteristics of lymphocyte components of the thymus were determined by two-color flow cytometry using monoclonal antibodies to T cell-differentiation antigens and activation antigens, and B cells in eight myasthenia gravis (MG) thymuses and eight thymomas including four associated with MG to clarify the roles of thymus in the diseases. Fifteen normal thymuses and four thymuses from non-MG patients were used as controls. Phenotypes of lymphoid components in thymoma resembled those in normal thymuses, in which the majority of lymphoid cells were immature (common) thymocytes (CD4+CD8+ or CD1+CD3-). The proportions of immature thymocytes, however, were relatively higher and those of mature thymocytes (CD4+CD8-, CD4-CD8+, CD1-CD3+ or CD2+CD3+) were lower in thymomas than normal thymuses. The results speculate that functions which support further differentiations of immature thymocytes into mature thymocytes are deficient in neoplastic epithelial cells of thymoma. In thymomas, therefore, occasional T cells might escape from the thymic surveillance system which eliminates auto-reactive T cells. Between thymomas associated with MG and those without, however, no significant difference was found in the proportions of thymocytes at various stages of maturation. In nonthymomatous thymuses from MG patients, an increase of both B cells (CD2-DR+ or CD2-CD21+) and activated T cells (CD2+DR+ or CD2+IL-2R+) was observed. Furthermore, immature thymocytes were significantly decreased and mature thymocytes were increased in the MG thymuses, as compared with normal thymuses, non-MG thymuses, and thymomas. These alterations were relevant to the histological findings observed in MG thymuses such as thymic involutions and germinal center formations: decreased immature thymocytes are considered to reflect thymic involutions, while germinal centers, in which lymphocytes from peripheral lymphoid organs are activated, are responsible for the increase of B cells, activated T cells, and mature T cells. In conclusions, our results suggest that neoplastic epithelial cells of thymomas are functionally deficient and that MG thymuses are immunologically active and resemble peripheral lymphoid organs.

Antibodies, Monoclonal↗
PubMed1992

Inhibition mechanism of reconstituted cytochrome P-450scc-linked monooxygenase system by antimycotic reagents and other inhibitors.

The effects of various antimycotic reagents and some other reagents on a cytochrome P-450-linked monooxygenase system were investigated with respect to the activities of NADPH-ferricyanide reductase. NADPH-cytochrome c reductase of NADPH-adreno-ferredoxin reductase from NADPH to cytochrome c via adreno-ferredoxin, NADPH-cytochrome P-450-phenylisocyanide complex reductase, and the cholesterol side chain cleavage of the cytochrome P-450scc-linked monooxygenase system. No reagents inhibited the NADPH-ferricyanide reductase activity. Only cloconazole inhibited about 50% of NADPH-cytochrome c reductase activity. Cloconazole, econazole, clotrimazole, etomidate and ketoconazole inhibited both NADPH-cytochrome P-450-phenylisocyanide complex reductase and the side chain cleavage activity of cholesterol of the cytochrome P-450scc-linked monooxygenase system. Cloconazole, econazole, etomidate and ketoconazole behaved like non-competitive inhibitors for NADPH-cytochrome P-450-phenylisocyanide reductase activities and their Ki values were 10(-4)-10(-6) M. Cloconazole was a non-competitive inhibitor of NADPH-cytochrome c reductase and its Ki value was 8.3 x 10(-4) M. Cloconazole, clotrimazole, econazole, etomidate, ketoconazole and mitotane completely inhibited the side chain cleavage activity of cholesterol.

Adrenal Cortex↗
PubMed1992

Choleretic effects of alpha-iridodiol on experimentally induced intrahepatic cholestasis.

When a lymphokine, the cholestatic factor, was intravenously injected into rats through a mesenteric vein, a remarkable reduction in bile flow was observed. Using this experimentally induced intrahepatic cholestasis model, we studied the choleretic effects of alpha-iridodiol, an iridoid compound. When alpha-iridodiol was administered 30 min before, at the same time, or 30 min after injection of the cholestatic factor, the reductions in bile flow and bile acid excretion were significantly inhibited. Remarkable choleretic effects were also noted when it was administered to normal rats. These results suggested that alpha-iridodiol may be effective in the treatment of intrahepatic cholestasis.

Animals↗
PubMed1992

[Evaluation of aerosol therapy of streptomycin for tracheobronchial and pulmonary tuberculosis].

The clinical features of tracheobronchial tuberculosis are distinct from those of pulmonary tuberculosis in some aspects. Streptomycin (SM) is claimed by some investigators that it has a tendency to promote the development of bronchial stenosis due to scarred healing of the involved endobronchial mucosa, and, for that reason, they recommend not to use it in treatment of bronchial tuberculosis. In some patients with pulmonary tuberculosis, who have renal or hearing disturbance, SM avoided. Yet unless SM is used improvement of tuberculosis could be delayed. It is the purpose of the present investigation to point out that aerosol therapy of SM is useful for patients with respiratory tuberculosis. Furthermore, we wish to demonstrate that we can safely treat the patients with respiratory tuberculosis who suffer from renal function or hearing disorder by use of aerosol therapy of SM. Prior to clinical application of the inhalation therapy, we confirmed that the therapy was not harmful. Serum concentration of SM, when inhaled, was measured in 9 volunteers. Before and after administration of SM aerosol, spirograms were examined in 4 volunteers, nevertheless, no special abnormality was recognized. It seemed that serum concentration of SM after the administration was two low to evoke adverse reactions (less than 3.0 gamma). In 6 patients with pulmonary tuberculosis, blood gases were measured and no obvious change was observed. As a result, it was demonstrated that the endobronchial tuberculous lesions improved faster when treated by inhalation of aerosolized SM as compared with the conventional injection therapy, without evoking any apparent adverse reactions. In some of the patients with pulmonary tuberculosis, it seemed that the therapy was useful.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[A case of pneumonia due to Mycoplasma pneumoniae accompanying high adenosine deaminase activity in pleural effusion].

We experienced a 5-year-old male case of Mycoplasma pneumoniae pneumonia accompanying Adenosine Deaminase (ADA) activity in pleural effusion. Chest roentgenograms revealed the infiltration in the left upper lung field and the left pleural effusion. In serum, the M. pneumoniae CF titer increased to 1:512. The pleural effusion was yellowish in color, with a specific gravity of 1.030, protein 3.7 g/dl, glucose 101 g/dl, and ADA 50 IU/l. Pleural effusion accompanying M. pneumoniae pneumonia is rare, and the high ADA activity in this case has been reported only in one other case. This is a report of a high activity of ADA in the pleural fluid by M. pneumoniae pneumonia.

Adenosine Deaminase↗