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Y Okawa

Publications and source records attributed to Y Okawa.

At least 37 records · Page 2Linked to original sources
PubMed1997

Characterization of beta-1,2-mannosyltransferase in Candida guilliermondii and its utilization in the synthesis of novel oligosaccharides.

A particulate insoluble enzyme fraction containing mannosyltransferases from Candida guilliermondii IFO 10279 strain cells was obtained as the residue after extracting a 105,000 x g pellet of cell homogenate with 1% Triton X-100. Incubation of this fraction with a mannopentaose, Manalpha1-->3(Manalpha1-->6)Manalpha1-->2Manalpha1+ ++-->2Man, in the presence of GDP-mannose and Mn2+ ion at pH 6.0 gave a third type of beta-1,2 linkage-containing mannohexaose, Manbeta1-->2Manalpha1-->3(Manalpha1-->6)Manalpha1++ +-->2Manalpha1-->2Man , the structure of which was identified by means of a sequential NMR assignment. The results of a substrate specificity study indicated that the beta-1,2-mannosyltransferase requires a mannobiosyl unit, Manalpha1--> 3Manalpha1-->, at the nonreducing terminal site. We synthesized novel oligosaccharides using substrates possessing a nonreducing terminal alpha-1,3-linked mannose unit prepared from various yeast mannans. Further incubation of the enzymatically synthesized oligosaccharide with the enzyme fraction gave the following structure, Manbeta1-->2Manbeta1-->2Manalpha1-->3(Manalpha1- ->6)Manalpha1--> 2Manalpha1-->2Man, which has been found to correspond to antigenic factor 9. Incubation of Candida albicans serotype B mannan with the enzyme fraction gave significantly transformed mannan, which contains the third type of beta-1,2-linked mannose units.

Antigens, Fungal↗
PubMed1997

Demonstration of the presence of alpha-1,6-branched side chains in the mannan of Candida stellatoidea.

A mild acetolysis of the mannans of Candida stellatoidea was performed after acetylation to yielded an alpha-1,6-branched mannohexaose, the presence of which had been predicted from the appearance of a specific H1-H2-correlated cross-peak in two-dimensional homonuclear Hartmann-Hahn spectroscopy. In this study, we found that the de-O-acetylation of a 4-O-acetyl group at the branching point, the 3,6-di-O-substituted mannose unit, of an acetylated oligosaccharide by sodium methoxide is significantly slower than that of other acetyl groups. We could separate the 4-O-acetylated branching oligosaccharide from linear isomer using high-performance liquid chromatography. Before and after the de-O-acetylation of the purified branching oligosaccharide, their 1H-NMR signals were sequentially assigned by means of the nuclear Overhauser effect. In the sequential NMR assignment study, we showed that the alpha-1,6-linked mannose unit is attached to the 3-O-substituted unit based on the presence of NOE cross-peak between H1 of the branching mannose unit and H6 of the 3-O-substituted mannose unit. An enzyme-linked immunosorbent inhibition assay of the reactivity of factor 4 serum to C. stellatoidea mannan by several oligosaccharides indicated that the alpha-1,6-branched oligosaccharide and the beta-1,2 linkage-containing oligosaccharides showed inhibitory activity. This result indicates that factor 4 serum, as well as factor 5 and 6 sera, contains antibodies against beta-1,2-linked mannose units which have been reported to participate in pathogenicity via cytokine production and/or adherence. From the assignment results of H1-H2-correlated cross-peaks of oligosaccharides and mannans, the molar ratio of the mannan side chains was proposed. In this study, we demonstrated that the epitope structure of the C. stellatoidea type I strains was the same as that of the C. albicans NIH B-792 (serotype B) strain.

Acetates↗
PubMed1997

Structure of a cell wall mannan from the pathogenic yeast, Candida catenulata: assignment of 1H nuclear magnetic resonance chemical shifts of the inner alpha-1,6-linked mannose residues substituted by a side chain.

We performed an enzyme-linked immunosorbent assay of the cell wall mannan purified from the pathogenic yeast, Candida catenulata, using antisera to factors of the genus Candida. The results suggest that mannan possesses a linear backbone consisting of alpha-1, 6-linked mannose residues and side chains possessing nonreducing terminal alpha-1,2- and alpha-1,3-linked mannose residues. The chemical structure of the mannan was analyzed by two-dimensional homonuclear Hartmann-Hahn and two-dimensional nuclear Overhauser enhancement and exchange spectroscopy. The sequential assignments of the cross-peaks caused by J-coupling and the nuclear Overhauser effect from these terminal mannose residues demonstrate that the H1 signal of an inner alpha-1,6-linked mannose residue substituted by an alpha-oligomannosyl side chain or a single mannose through the C-2 position in an alpha-anomer configuration undergoes a significant downfield shift (delta delta = 0.16 or 0.19 ppm, respectively) compared with that of unsubstituted residues. We therefore propose the exact overall structure of the antigenic mannan obtained from C. catenulata. The assignment data in the present study are useful for the determination of the exact overall structure of various yeast mannans using the two-dimensional nuclear magnetic resonance analysis without the need for harsh procedures.

Antigens, Fungal↗
PubMed1997

NMR study of the galactomannans of Trichophyton mentagrophytes and Trichophyton rubrum.

Around 90% of chronic dermatophyte infections are caused by the fungi Trichophyton mentagrophytes and Trichophyton rubrum. One of the causes of the chronic infection resides in the immunosuppressive effects of the cell-wall components of these organisms. Therefore we have attempted to identify the chemical structure of galactomannan, one of the major cell-wall components. The cell-wall polysaccharides secreted by T. mentagrophytes and T. rubrum were isolated from the culture medium and fractionated into three subfractions by DEAE-Sephadex chromatography. Analysis of each subfraction by NMR indicated that there are two kinds of polysaccharides present, i.e. mannan and galactomannan. The mannan has a linear backbone consisting of alpha1,6-linked mannose units, with alpha1,2-linked mannose units as side chains. The core mannan moiety of the galactomannan was analysed by a sequential NMR assignment method after removing the galactofuranose units by acid treatment. The result indicates that the mannan moiety has a linear repeating structure of alpha1,2-linked mannotetraose units connected by an alpha1,6 linkage. The H-1 signals of the two intermediary alpha1, 2-linked mannoses of the tetraose unit showed a significant upfield shift (Deltadelta=0.05-0.08 p.p.m.), due to the steric effect of an alpha1,6-linked mannose unit. The attachment point of the galactofuranose units was determined at C-3 of the core mannan by the assignment of the downfield-shifted 13C signals of the galactomannan compared with those of the acid-modified product. In these galactomannans there were no polygalactofuranosyl chains which have been found in Penicillium charlesii and Aspergillus fumigatus.

Carbohydrate Conformation↗
PubMed1997

Association between frequency of amino acid changes in core region of hepatitis B virus (HBV) and the presence of precore mutation in Japanese HBV carriers.

To elucidate the relationship between the frequency of core mutations and precore mutation of hepatitis B virus (HBV) in Japanese HBV carriers, we investigated the nucleotide sequence of the precore/core region of HBV in 26 Japanese HBV carriers [15 who were HBe antigen-negative (HBeAg-) and 11 who were HBeAg-positive (HBeAg+)]. The number of amino acid changes (5.9 +/- 3.8) in the core region of HBV in HBeAg-carriers was significantly greater than that in the HBeAg+ carriers (1.5 +/- 1.0; P < 0.005). The precore stop codon mutation was found in 93.3% of HBeAg-negative HBV carriers, while no precore mutation was found in the HBeAg-positive HBV carriers, suggesting that the frequency of core mutations may be associated with the presence of the precore stop codon mutation. However, there was no significant difference in the frequency of amino acid changes among HBeAg-HBV carriers. The mean number of core amino acid changes of liver cirrhosis patients, chronic active hepatitis patients, chronic persistent hepatitis patients, and asymptomatic carriers were 2.7 +/- 1.5, 6.0 +/- 2.2, 4.7 +/- 1.2, and 8.4 +/- 5.3, respectively. We detected hot spots for core mutations, which showed characteristic localizations and specific substitutions: Gly-87, Leu-97, and Thr-130 were detected exclusively in patients with chronic liver disease with or without HBeAg. To address further the relationship between frequency of core mutations and the presence of the precore stop codon mutation, we investigated the precore/core nucleotide sequence serially along with seroconversion in three patients with chronic hepatitis B in whom the hepatitis either became inactive or remained active after the seroconversion. Emergence of the precore stop codon mutation and a significant increase in core amino-acid changes after seroconversion were noted in all three patients. Our results suggest a close association between the frequency of core amino acid changes and the presence of the precore stop codon mutation; some characteristic core mutations may be associated with the clinical course of chronic hepatitis B in Japanese patients.

Adult↗
PubMed1997

Production of monoclonal antibody discriminating serological difference in Escherichia coli O9 and O9a polysaccharides.

A monoclonal antibody (mAb) with a unique antigenic specificity against Escherichia coli O9 was produced. The O9a mAb was reactive with a part of the strains in E. coli O9. The O9a mAb did not react with LPS from the E. coli O9 test strain Bi316-42. The distribution of the antigen defined by the O9a mAb in E. coli O9 was consistent with that of E. coli O9a present in E. coli O9 strains. The chemical structure of the repeating unit of the O-specific polysaccharide detected by the mAb was demonstrated to be a mannotetraose by two-dimensional nuclear magnetic resonance spectroscopy. It was confirmed that the mAb recognized E. coli O9a serotype in E. coli O9 serotype strains, suggesting that E. coli O9a serotype might be a dominant strain in E. coli O9.

Animals↗
PubMed1997

Urgent liver transplantation for biliary atresia: the experience in Bicêtre.

According to French rules for cadaver organ sharing, children with biliary atresia (BA) complicated with acute necrosis (ALN) can be registered on the waiting list for liver transplantation (LT) in a special intermediate grade urgent code. Over a 7 years period, 100 children have been submitted to elective LT for BA and 15 to urgent LT. Urgent procedures accounted for 25% of LT for BA in patients aged 0-2 years and 67% (8/12) in patients under 1 year of age. Children actuarial survival at 1, 12 and 48 months was respectively 66%, 60% and 60% versus 92%, 86% and 85%, deaths occurring earlier in the urgent group. Graft actuarial survival at 1, 12 and 48 months were 60%, 53% and 53% versus 85%, 77% and 76% (p < 0.05), respectively. Outcome of children and grafts after LT is not significantly different in BA cases and in other urgent indications, excluding retransplantations. In a LT program based on cadaver organ donation, allocation of in an urgent registration code to children with BA and ALN offers them more than 50% chance to escape death and does not result in wasting of grafts.

Actuarial Analysis↗
PubMed1997

[The causes and management of ischemic mitral regurgitation].

Ischemic mitral regurgitation (IMR) is recognized as one of the complications of coronary artery disease. The aim of this study is to evaluate the causes and surgical management of IMR. From October 1986 to March 1995, 443 of patients underwent isolated coronary artery bypass grafting (CABG). In forty-four of the patients (9.9%) who underwent isolated CABG, the severity of postoperative IMR was reduced by two or more grades by the Sellers index. Hemodynamic parameters of these patients included: left ventricle ejection fraction, left ventricle end-diastolic volume index and left ventricle regional wall motion. They were assessed by left ventriculography (LVG). In addition, cardiac index and pulmonary artery wedge pressure were assessed by S-G catheterization and mitral annulus diameter by ultrasonic echocardiography. Twenty-nine patients experienced an increase in IMR severity after CABG, one of whom required mitral valve replacement for cardiac failure, and later died due to low output syndrome postoperative. On the other hand, fifteen patients experience a reduction in IMR severity after CABG. We conclude that the causes of IMR were regional asynergy at the site of papillary muscle, mitral annulus dilation and left ventricle dilation. Our findings suggest that severe IMR patients required concomitant mitral valve surgery with CABG. Patients with mild or moderate IMR patients with mitral annulus dilation or regional asynergy at the site of mitral papillary muscle may require the same surgery.

Coronary Artery Bypass↗
PubMed1996

Structure and antigenicity of the mannans of Candida famata and Candida saitoana: comparative study with the mannan of Candida guilliermondii.

The chemical structure of the mannans of antigenic factor 9-expressing yeast, Candida famata and Candida saitoana, was analyzed by acetolysis and NMR. The structural study of the oligosaccharides and mannans using one- and two-dimensional NMR indicated that the mannan of C. saitoana contains a third type of beta-1,2-linked mannose unit. On the other hand, the mannan of C. famata does not contain any beta-1,2-linked mannose units. The mannan of C. saitoana gave two groups of beta-1,2 linkage-containing oligosaccharides by acetolysis. One contains one beta-1,2-linked mannose unit and the other contains two consecutive beta-1,2-linked mannose units at the nonreducing terminal. The inhibition of the reactivity of factor 9 serum on an enzyme-linked immunosorbent assay (ELISA) with these oligosaccharides indicated that the inhibition activity of the former oligosaccharide is 1/20 of that of the latter ones. The ELISA of the mannans of Candida guilliermondii, C. saitoana, and Saccharomyces kluyveri, all of which contain the third type of beta-1,2-linked mannose unit, indicated that Man(beta)1--> 2Man(beta)1-->2Man(alpha)1-->3Man(alpha)1-->works as the antigenic factor 9 but Man(beta)1-->2Man(alpha)1-->3Man(alpha)1--> weakly behaves as both antigenic factors 6 and 9. The epitope structures of the side chain oligosaccharides agreed well with that proposed from the 2D-HOHAHA spectra of the mannans. This result demonstrates the usefulness of the H-1 - H-2-correlated cross-peak pattern, which was reported in a preceding paper (Shibata, N., Akagi, R., Hosoya, T., Kawahara, K., Suzuki, A., Ikuta, K., Kobayashi, H., Hisamichi, K., Okawa, Y., and Suzuki, S. (1996) J. Biol. Chem. 271, 9259-9266) for the determination of the epitope structure of Candida mannans without any chemical fragmentation.

Acetic Acid↗
PubMed1996

Identification of the antigenic determinants of factors 8, 9, and 34 of genus Candida.

We investigated the antigenic determinants of factors 8, 9, and 34 of the genus Candida among pathogenic yeasts by enzyme-linked immunosorbent assay (ELISA) using mannans of Saccharomyces cerevisiae wild type and mutant types, mnn 1-mnn 4 and mnn 2. Results of ELISA including antisera against the antigenic factors of genus Candida (Candida Check, latron; FAbs) indicated that these three types of mannan distinctly react with FAbs 34, 8 and 9, respectively. To identify the recognition sites of these FAbs, we compared the ability of various oligosaccharides to inhibit the binding of the mannans to FAbs. The results indicated that FAb 34 preferentially recognizes linear side chains containing a non-reducing terminal alpha-1,3-linked mannose residue, Man(alpha)1 --> 3Man(alpha)1 --> (2Man(alpha)1 --> )n(2Man) (n > or = 0), and that one of the recognition sites of FAb 9 is linear alpha-1,6-linked oligomannosyl series, Man(alpha)1 --> (6Man(alpha)1 --> )n(6Man) (n > or = 2). On the other hand, the recognition site of FAb 8 apparently consisted of two alpha-1,2-linked oligomannosyl side chains and an alpha-1,6-linked mannose residue that originated from the mannan backbone, Man(alpha)1 --> 2Man(alpha)1 --> 2(Man(alpha)1 -->2Man(alpha)1 --> 6)Man.

Antigens, Fungal↗
PubMed1996

Characterization of alpha-1,6-mannosyltransferase responsible for the synthesis of branched side chains in Candida albicans mannan.

A particulate insoluble fraction from Candida albicans NIH B-792 (serotype B) strain cells was obtained as the residue after extracting a 105000 x g pellet of cell homogenate with 1% Triton X-100. Incubation of this fraction with a mannopentaose, Man alpha 1-->3Man alpha 1-->2Man alpha 1-->Man alpha 1-->2Man, in the presence of GDP-mannose and Mn2+ at pH 6.0 gave a branched mannohexaose, [sequence: see text] 6 the structure of which was identified by means of sequential off assignment. However, the enzyme fraction obtained from Candida parapsilosis gave Man alpha 1-->2Man alpha 1-->3Man alpha 1-->2Man alpha 1-->2 Man alpha 1-->2Man under the same conditions. These results demonstrate the finding that the structural difference in the mannans of these two species is due to the presence of alpha-1.6-linked branching mannose units in the C. albicans mannan [Shibata, N., Ikuta, K., Imai, T., Satoh, Y., Satoh, R., Suzuki, A., Kojima, C., Kobayashi, H., Hisamichi, K. & Suzuki, S. (1995) J. Biol. Chem. 270, 1113-1122]. The substrate-specificity study of the enzyme indicated that the structural requirement of the alpha-1,6-mannosyltransferase is Man alpha 1-->3Man alpha 1-->. The alpha-1,6-mannosyltransferase also transferred the alpha-1,6-linked branching mannose unit to the mannan of Saccharomyces cerevisiae. The transformation of the mannan was detected by the appearance of antigenic factor 4 using an enzyme-linked immunosorbent assay and two-dimensional homonuclear Hartmann-Hahn spectroscopy.

Candida↗
PubMed1996

Existence of novel branched side chains containing beta-1,2 and alpha-1,6 linkages corresponding to antigenic factor 9 in the mannan of Candida guilliermondii.

Isolation of beta-linkage-containing side chain oligosaccharides from the mannan of Candida guilliermondii IFO 10279 strain has been conducted by acetolysis under mild conditions. A structural study of these oligosaccharides by one- and two-dimensional NMR and methylation analyses indicated the presence of extended oligosaccharide side chains with two consecutive beta-1,2-linked mannose units at the nonreducing terminal of alpha-linked oligosaccharides. The linkage sequence present in this mannan, Man beta 1-->2Man alpha 1-->3Man alpha-->, has also been found in the mannan of Saccharomyces kluyveri but not in the mannan of Candida species. Furthermore, these oligosaccharides are branched at position 6 of the 3-O-substituted mannose units as follows. (Carbohydrate sequence in text) Structure 1 and (Carbohydrate sequence in text) Structure 2 The H-1 signals of the mannose units substituted by a 3,6-di-O-substituted unit showed a significant upfield shift (delta delta = 0.04-0.08 ppm) due to a steric effect. The inhibition of an enzyme-linked immunosorbent assay between the mannan of C. guilliermondii and factor 9 serum with oligosaccharides obtained from several mannans indicated that only the oligosaccharides with the above structure were active, suggesting that these correspond to the epitope of antigenic factor 9.

Antigens, Fungal↗
PubMed1996

Preoperative diagnosis of intratemporal facial nerve tumor: high-resolution CT and otoscopic findings in 4 cases.

Four cases of facial nerve tumor were treated in our clinic during the past 16 years, one of which was a recurrence 12 years after the resection. Another case presented with relapsing facial palsy of sudden onset. The others presented with slowly progressive facial palsy. In each of the four cases, the horizontal and vertical portions were included in the tumor extension, and a mass was revealed in the posterior tympanic cavity by use of otoscopy. High-resolution CT, performed in all but the earliest case, proved to be the most valuable diagnostic tool, indicating the anatomical correlation of the tumor with the facial canal. With the diagnosis preoperatively established, facial reanimation procedure could be applied immediately after the tumor resection except in the recurrent case.

Cranial Nerve Neoplasms↗
PubMed1996

Antigenicity of cell wall mannans of Candida albicans NIH B-792 (serotype B) strain cells cultured at high temperature in yeast extract-containing sabouraud liquid medium.

Cultivation of Candida albicans NIH B-792 (serotype B) at high temperature (37 degrees C) for 48 h in yeast extract-containing Sabouraud liquid medium (YSLM) provided the following findings in comparison with the findings obtained after incubation at 27 degrees C. Growth of the blastoconidia of this strain was decreased, with a dry weight of 9%, and the cells were deficient in cytokinesis. The cells did not undergo agglutination with serum factor 5 from a commercially available serum factor kit (Candida Check). Mannan (B-37-M) obtained from the cells cultured at 37 degrees C had partially lost its reactivity against serum factor 4 and lost most of its reactivity against serum factor 5 in an enzyme-linked immunosorbent assay (ELISA) in contrast to that (B-27-M) at 27 degrees C. Both cells and mannan prepared by cultivation first at 37 degrees C and then at 27 degrees C entirely recovered their reactivities with serum factors 4 and 5. 1H-nuclear magnetic resonance analysis also revealed that B-37-M had lost a beta-1,2-linked mannopyranose unit and retained a phosphate group. Similar changes were observed in the three other serotype B strains used in the study. The beta-1,2-linked mannooligosaccharides longer than mannotetraose were not included among the products released from B-37-M by mild acid treatment. The results of the inhibition ELISA with a series of beta-1,2-linked mannooligosaccharides from biose to octaose (M2 to M8, respectively) showed that the reactivity against serum factor 4 was inhibited most strongly by the oligosaccharides M4 to M8 and that the reactivity against serum factor 5 was inhibited completely by relatively longer oligosaccharides, M5 to M8, indicating their participation as the antigenic factor 5 epitopes.

Agglutination Tests↗
PubMed1996

[Influence of total parenteral nutrition in immature rats: effect of glutamine infusion on bowel integrity].

Total parenteral nutrition (TPN) is accepted important therapeutic adjunct in spite of many complications for management of pediatric patients who aren't allowed to eat. Recently, bacterial translocation was added to the complications of TPN. The purpose of this study was to examine the influence of TPN on the gut in immature rats. 65g rats were randomized to one of four groups: Group C (control) received food and water ad libitum. Group P (TPN) received standard TPN solution. Group G (TPN+GLT) received glutamine (7g/400ml of TPN). Group E (TPN with enhanced protein) received TPN solution with enhanced protein (18.5g/400ml), without GLT. CFU of E. coli in mesenteric lymphnodes was significantly higher in group P than in other 3 groups at 5 days. Hepatic glutathione was significantly higher in group G than in group P and group E at 7 days. Weight of wet intestine was the highest in group C in all groups, and significantly higher in group G than in group P and group E at 3 and 7 days. Mucosal protein of group C was the highest of those of 4 groups. That of group G was significantly higher than those of group P and G in 5 and 7 days. Mucosal thickness and villous height were the highest in group C in 4 groups. Mucosal thickness was significantly higher in group G than in group P and group E at 5 and 7 days. Villous height was significantly higher in group G P and group E at all days. These results suggest that TPN promotes intestinal atrophy from early days after TPN in immature rats, that glutamine might play a role in maintenance of structural integrity of intestine, and that glutamine would prevent the bacterial translocation.

Animals↗
PubMed1996

[A case of coronary perforation after directional coronary atherectomy].

Directional coronary atherectomy was performed on a 69-year-old female with angina pectoris. She suffered from coronary perforation as a result of cardiac tamponade and shock. Pericardial drainage and hemostasis were performed immediately using a perfusion catheter. The patient was transferred to the operating room for perforation repair and coronary artery bypass grafting to the distal portion of the left anterior descending artery. The procedure was performed successfully. Although acute coronary perforation associated with directional coronary atherectomy is rare, it can be managed temporarily by a perfusion catheter and we successfully performed coronary artery bypass grafting.

Aged↗