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T Okamoto

Publications and source records attributed to T Okamoto.

At least 271 records · Page 15Linked to original sources
PubMed1999

Genetic heterogeneity of the immunogenic viral capsid protein region of human parvovirus B19 isolates obtained from an outbreak in a pediatric ward.

Whereas human parvovirus B19 commonly infects children and causes erythema infectiosum, it causes more severe diseases when it infects adults. In order to examine whether different clinical outcomes of B19 infection can be ascribed to the viral genetic heterogeneity, we have determined the nucleotide sequence of highly immunogenic portions of the B19 genome obtained from six patients with various clinical manifestations in a single outbreak. Our observations demonstrated that although the B19 sequences showed a significant heterogeneity, it was not correlated with the clinical manifestation. It was thus suggested that the host immune response to B19 infection may be a major determinant of clinical presentations associated with acute B19 infection.

Adult↗
PubMed1999

The significance of microsatellite instability in predicting the development of metachronous multiple colorectal carcinomas in patients with nonfamilial colorectal carcinoma.

BACKGROUND: Patients with metachronous multiple colorectal carcinomas have been reported to have a higher frequency of a family history of colorectal carcinoma, associated colorectal adenomas, and extracolonic malignancies. These clinicopathologic factors also are considered to be related to the development of metachronous multiple colorectal carcinomas after surgery for colorectal carcinoma. In this article, the authors investigated whether genetic markers such as microsatellite instability (MSI) were helpful in predicting the development of metachronous multiple colorectal carcinomas. METHODS: Between 1990-1997, 312 colorectal carcinoma patients underwent yearly surveillance colonoscopy after surgery. Among these patients, there were 19 with nonfamilial colorectal carcinoma in whom metachronous multiple colorectal carcinomas were diagnosed during the yearly surveillance colonoscopy. A control group was comprised of 28 patients who did not demonstrate either synchronous or metachronous carcinomas over a period of > or =5 years. Six microsatellite markers (D2S123, D3S1029, D3S1611, TP53, Mfd26, and Mfd36) were used to determine MSI by polymerase chain reaction. RESULTS: The frequency of MSI positive cases was significantly higher in patients with sporadic metachronous multiple colorectal carcinomas than in those with a single carcinoma (17/19 [89%] vs. 4/28 [14%]; P<0.0001). In tumors occurring in the distal colon and rectum, the percentage of MSI positive carcinomas was significantly higher in the patients with metachronous multiple carcinomas than in those with a single carcinoma (13/15 [87%] vs. 0/19 [0%]; P<0.0001). No such difference was observed in the proximal colon. CONCLUSIONS: Based on the findings of the current study, the analysis of MSI in sporadic carcinomas of the distal colon and rectum may be helpful in predicting the development of metachronous multiple colorectal carcinomas.

Colonoscopy↗
PubMed1999

Flotillins/cavatellins are differentially expressed in cells and tissues and form a hetero-oligomeric complex with caveolins in vivo. Characterization and epitope-mapping of a novel flotillin-1 monoclonal antibody probe.

Caveolae are vesicular organelles that represent a subcompartment of the plasma membrane. Caveolins and flotillins are two families of mammalian caveolae-associated integral membrane proteins. However, it remains unknown whether flotillins interact with caveolin proteins to form a stable caveolar complex or if expression of flotillins can drive vesicle formation. Here, we examine the cell type and tissue-specific expression of the flotillin gene family. For this purpose, we generated a novel monoclonal antibody probe that recognizes only flotillin-1. A survey of cell and tissue types demonstrates that flotillins 1 and 2 have a complementary tissue distribution. At the cellular level, flotillin-2 was ubiquitously expressed, whereas flotillin-1 was most abundant in A498 kidney cells, muscle cell lines, and fibroblasts. Using three different models of cellular differentiation, we next examined the expression of flotillins 1 and 2. Taken together, our data suggest that the expression levels of flotillins 1 and 2 are independently regulated and does not strictly correlate with known expression patterns of caveolin family members. However, when caveolins and flotillins are co-expressed within the same cell, as in A498 cells, they form a stable hetero-oligomeric "caveolar complex." In support of these observations, we show that heterologous expression of murine flotillin-1 in Sf21 insect cells using baculovirus-based vectors is sufficient to drive the formation of caveolae-like vesicles. These results suggest that flotillins may participate functionally in the formation of caveolae or caveolae-like vesicles in vivo. Thus, flotillin-1 represents a new integral membrane protein marker for the slightly larger caveolae-related domains (50-200 nm) that are observed in cell types that fail to express caveolin-1. As a consequence of these findings, we propose the term "cavatellins" be used (instead of flotillins) to describe this gene family.

Amino Acid Sequence↗
PubMed1999

Posttranslational removal of the carboxyl-terminal KDEL of the cysteine protease SH-EP occurs prior to maturation of the enzyme.

SH-EP is a cysteine protease from germinating mung bean (Vigna mungo) that possesses a carboxyl-terminal endoplasmic reticulum (ER) retention sequence, KDEL. In order to examine the function of the ER retention sequence, we expressed a full-length cDNA of SH-EP and a minus-KDEL control in insect Sf-9 cells using the baculovirus system. Our observations on the synthesis, processing, and trafficking of SH-EP in Sf-9 cells suggest that the KDEL ER-retention sequence is posttranslationally removed either while the protein is still in the ER or immediately after its exit from the ER, resulting in the accumulation of proSH-EP minus its KDEL signal. It is this intermediate form that appears to progress through the endomembrane system and is subsequently processed to form mature active SH-EP. The removal of an ER retention may regulate protein delivery to a functional site and present an alternative role for ER retention sequences in addition to their well established role in maintaining the protein composition of the ER lumen.

Animals↗
PubMed1999

Protective effect of gamma-glutamylcysteinylethyl ester on dysfunction of the selenium-deficient rat heart.

We investigated the protective effect of intracellular GSH against cardiac dysfunction in selenium (Se)-deficient neonatal rats and cultured fetal rat myocytes. A Se-deficient diet with or without daily subcutaneous injections of gamma-glutamylcysteinylethyl ester (gammay-GCE) (a membrane-permeating GSH precursor) was given to rats from gestation day 4 via the dam to postnatal day 14. Se deficiency induced a 62% incidence of electrocardiographic abnormalities such as sinus arrhythmias or extrasystole, a 63% reduction in dP/dt in the left ventricle, and an increase in thiobarbituric acid reacting substances (TBARS), but no ultrastructural cardiac lesions were observed. Administration of gamma-GCE increased the intracellular GSH concentration ([GSH]i) of both neonatal rat hearts and cultured fetal rat cardiac myocytes. gamma-GCE-like sodium selenite prevented the cardiac dysfunction and the TBARS increment. gamma-GCE also prevented H2O2 toxicity in the cultured myocytes. The Vmax, but not the Km, for GSH of Se-dependent GSH peroxidase (Se-Gpx) activity in Se-deficient rat heart homogenates was one-third that of normal rat heart homogenates. Although gamma-GCE did not affect the Se-Gpx Vmax and Km for GSH, it did induce a substantial and significant increase in [GSH]i, which was postulated to increase the velocity of H2O2 decomposition by Se-Gpx activity 1.6-fold. These data suggest that the increase in [GSH]i may have played a role in preventing the TBARS increase and cardiac dysfunction in Se-deficient rats.

Analysis of Variance↗
PubMed1999

Isolation and characterization of new limonoid glycosides from Citrus unshiu peels.

Three limonoid glycosides were isolated from Citrus unshiu peels, and their structures were determined based on MS and NMR spectroscopic data as nomilinic acid 17-O-beta-D-glucopyranoside (1), methyl nomilinate 17-O-beta-D-glucopyranoside (2), and obacunone 17-O-beta-D-glucopyranoside (3). In particular, the location of the sugar moiety was clearly determined by the B/E constant linked scan FABMS method. No limonoid glycosides obtained here were found to have antitumor activity in NCI-H292 and EL-4 cell lines.

Animals↗
PubMed1999

Transcription factor Y-box binding protein 1 binds preferentially to cisplatin-modified DNA and interacts with proliferating cell nuclear antigen.

The Y-box binding protein (YB-1) binds to inverted CCAAT box sequences that are present in the promoter region of many genes. We previously showed that YB-1 is overexpressed in human cancer cell lines that are resistant to cisplatin and that the depletion of YB-1 by transfection of a vector expressing YB-1 antisense RNA increases the sensitivity of human cancer cells to cisplatin. To determine whether YB-1 can bind to cisplatin-modified DNA, we fused YB-1 cDNA to glutathione S-transferase (GST) cDNA and purified the resulting GST fusion protein. When we tested the fusion protein with unmodified or cisplatin-modified oligonucleotides, we found that GST-YB-1 bound more strongly to cisplatin-modified oligonucleotides, as did GST fusion proteins of high mobility group 1 (HMG1), HMG2, and xeroderma pigmentosum group A protein. When we assayed the ability of proliferating cell nuclear antigen (PCNA) to interact with the GST fusion proteins, we observed binding to YB-1 but not to HMG1, HMG2, or xeroderma pigmentosum group A. Subsequent experiments demonstrated that YB-1 and PCNA interact directly via the COOH-terminal region of YB-1. Using immunochemical coprecipitation methods, we observed binding of YB-1 and PCNA in vivo. These results suggest that YB-1 can function as a recognition protein for cisplatin-damaged DNA and that it may be important in DNA repair or in directing the cellular response to DNA damage.

CCAAT-Enhancer-Binding Proteins↗
PubMed1999

Expression of the thioredoxin-thioredoxin reductase system in the inflamed joints of patients with rheumatoid arthritis.

OBJECTIVE: To examine the expression of the thioredoxin (TRX)-thioredoxin reductase (TR) system in patients with rheumatoid arthritis (RA) and patients with other rheumatic diseases. METHODS: Levels of TRX in plasma and synovial fluid (SF) were measured using enzyme-linked immunosorbent assay. Cellular distribution of TRX was determined by flow cytometry and histochemistry. Cellular expression of TR was studied by in situ messenger RNA (mRNA) hybridization. The effect of oxidative stress and tumor necrosis factor alpha (TNF alpha) on TRX expression by cultured rheumatoid fibroblast-like synoviocytes was studied. RESULTS: Significantly increased TRX levels were found in the SF from 22 patients with RA, when compared with plasma levels in the same patients (P < 0.001) and compared with SF TRX levels in 15 patients with osteoarthritis (P < 0.001), 13 patients with gout (P < 0.05), and 9 patients with reactive arthritis (P < 0.0001). The presence of TRX could be demonstrated within the SF-derived mononuclear cells and synovial tissue (ST) of RA patients. Concordantly, expression of TR mRNA was observed in the ST of these patients. Stimulation of synovial fibroblast-like synoviocytes with either H2O2 or TNF alpha induced an increase in the production of TRX. CONCLUSION: The data demonstrate significantly increased concentrations of TRX in the SF and ST of RA patients when compared with the levels in patients with other joint diseases. Evidence is presented that the local environment in the rheumatic joint contributes to increased TRX production. Based on its growth-promoting and cytokine-like properties, it is proposed that increased expression of TRX contributes to the disease activity in RA.

Aged↗
PubMed1999

Cytosolic NADPH-UQ reductase, the enzyme responsible for cellular ubiquinone redox cycle as an endogenous antioxidant in the rat liver.

Cellular ubiquinone (UQ) is expected to act as an endogenous antioxidant against oxidative stress. To confirm this, UQ-reductases which are necessary to regenerate ubiquinol (UQH2) were investigated in rat tissue, and a novel NADPH-dependent UQ (NADPH-UQ) reductase was found in cytosol. The cytosolic NADPH-UQ reductase activity accounted for more than 80% of UQ-10 reduction by the rat liver homogenate in the presence of NADPH. Furthermore, the NADPH-UQ reductase activities in various tissues were correlated to the redox states of UQ in the corresponding tissues. Rat liver cytosol with NADPH protected lecithin liposomes containing UQ-10, as well as UQH2-10 from AMVN (2,2'-azobis(2,4-dimethylvaleronitrile))-induced lipid peroxidation. The enzyme purified from rat liver cytosol, reduced UQ-10 in lecithin liposomes at approximately the same rate as did cytosol. These results supported that cytosolic NADPH-UQ reductase is the enzyme responsible for nonmitochondrial UQ reduction acting as an endogenous antioxidant against oxidative stress. The antioxidant role of the UQ redox cycle and NADPH-UQ reductase was discussed in relation to other cellular NADPH-dependent antioxidant enzymes.

Animals↗
PubMed1999

Ubiquinone redox cycle as a cellular antioxidant defense system.

Ubiquinone (UQ) reductase responsible for reduction of non-mitochondrial UQ was investigated in rats toward demonstrating an antioxidant role of UQ. In the liver, most of cellular UQ-10 reductase activity was attributable to a novel NADPH-UQ reductase in cytosol. The enzyme was not inhibited by dicumarol and rotenone, and had a Km of 19 microM for NADPH and 307 microM for NADH at the optimum pH 7.4. The enzyme was purified 300-fold to apparent homogeneity from the liver cytosol by an affinity chromatographic method. The purified enzyme reduced UQ-10 in lecithin liposomes, and protected the liposomes from lipid peroxidation. Furthermore, supplementation of rats with UQ-10 was observed to increase the enzyme level in their livers without affecting levels of other antioxidant factors. The observations suggested that cytosolic NADPH-UQ reductase is responsible for cellular UQ redox cycle as an endogenous antioxidant.

Animals↗
PubMed1999

Participation of platelet-activating factor in the lipopolysaccharide-induced liver injury in partially hepatectomized rats.

Platelet-activating factor (PAF) has been shown to be an important mediator in the pathogenesis of lipopolysaccharide (LPS)-induced liver injury in regenerating rat livers. Both LPS and PAF activate nuclear factor-kappa B (NF-kappaB), a key transcription factor for tumor necrosis factor-alpha (TNF-alpha) and cytokine-induced neutrophil chemoattractant (CINC). The aim of this study is to investigate how PAF participates in the LPS-induced and NF-kappaB-mediated regulation of TNF-alpha and CINC in regenerating rat livers. LPS (1.5 mg/kg) was intravenously administered into 70% hepatectomized rats and sham-operated rats 48 hours postoperatively. LPS administration caused a high mortality rate, scattered necrosis in the liver with infiltration of CINC-positive neutrophils, and a continuous CINC messenger RNA up-regulation and activation of NF-kappaB in the liver only in hepatectomized rats. These phenomena were all effectively prevented by pretreatment and posttreatment with a PAF receptor antagonist, TCV-309. Hepatectomized rats showed NF-kappaB staining in hepatocytes, Kupffer cells, and neutrophils around necrosis 4 hours after the LPS injection, representing the activation of this factor in these cells. Based on these results, we propose that PAF contributes to continuous CINC up-regulation and NF-kappaB activation via accumulation and activation of neutrophils, and thereby is involved in LPS-induced liver injury in regenerating rat livers.

Alanine Transaminase↗
PubMed1999

Intra-arterial vein bypass using a vein-loaded stent system to occlude wide-necked aneurysms: an experimental study in dogs.

We treated 13 experimental wide-necked aneurysms of lateral type produced in dog carotid arteries with a vein-loaded stent system consisting of an autologous vein graft, a vein-carrier stent, and two other self-expanding Z-shaped stents. The vein-loaded stent, made by connecting the autologous vein graft to the vein-carrier stent, was implanted in the common carotid artery to seal the aneurysm's orifice, after which two booster stents were deployed. The distal stent was placed to fix the distal end of the vein graft, and the proximal stent was placed at the proximal venous portion of the vein-loaded stent to reinforce its proximal end. In this manner an intra-arterial bypass was established across the aneurysm. Of 13 aneurysms seven were completely occluded, preserving the parent artery. The remaining six procedures resulted in parent artery occlusion because of failures in stent deployment. Angiograms performed in within 1 week six successfully treated dogs revealed the parent artery to be patent in four but thrombosed in two. Histological study of successful cases showed as smooth intima with slight endothelial hypertrophy and partially organised thrombus. The intraluminal features were also observed with a vascular endoscope at the time of treatment in four dogs and at the time of follow-up angiography in two. The appearances corresponded well to the macroscopic findings in the specimens. Our vein-loaded stent system offers complete closure of the orifice, which does not occur with conventional stent placement. The method is believed to show clinical promise for treating wide-necked aneurysms not curable by embolisation of the sac.

Aneurysm↗
PubMed1999

Synthesis and degradation of a 28-kDa pod storage protein in french bean (Phaseolus vulgaris) plants

Pod storage protein (PSP) accumulated in developing pods of French bean (Phaseolus vulgaris L.) plants, and increasing the PSP mRNA level by pod removal resulted in the enhancement of PSP accumulation in pods that formed later. Pod storage protein was detected in flowers, young leaves and young stem internodes in addition to pods. Accumulation of PSP and its mRNA was induced by sink-removal in an organ-specific manner. In addition, wounding induced PSP accumulation systemically in leaves. Methyl jasmonate did not induce PSP synthesis but enhanced the synthesis that was induced by wounding. In senescing pods, PSP was degraded, and degradation products with molecular masses of 20 and 17 kDa were detected in the pods. The amount of 20-kDa degradation product was greater than that of the 17 kDa product.

Journal Article↗
PubMed1999

Alteration of the cellular response to interleukin-1 beta by SV40 large T antigen in rheumatoid synovial fibroblasts.

The large T antigen of SV40 (LT) has been widely used to immortalize primary cells for various studies. In this study, synovial fibroblasts of a patient from rheumatoid arthritis (RA) were transformed with LT gene to analyze the effect of SV40-mediated transformation on the production of cytokines, such as IL-6, IL-8, and GM-CSF, that are under the control of interleukin-1 beta (IL-1 beta), a physiological inducer of nuclear factor kappa B (NF-kappa B). It was noted that the basal levels of GM-CSF and IL-8 were upregulated, whereas that of IL-6 was downregulated. Moreover, the extents of induction of these cytokines in response to IL-1 beta were markedly downregulated in synovial fibroblasts transformed by LT as compared from parental cells. Although IL-1 beta could translocate NF-kappa B to the nucleus in all cells, some of the transformed cells exhibited nuclear translocation of NF-kappa B even before the stimulation with IL-1 beta, suggesting that transformation of LT resulted in the constitutive activation of NF-kappa B, either directly or indirectly. In order to examine whether LT downregulate the kappa B-dependent gene expression, we performed the transient luciferase gene expression assay. We found that cotransfection of LT did not downregulate the kappa B-dependent gene expression that was stimulated with L-1 beta. These observations suggest that the apparent inhibitory effect of LT on the IL-1-induced expression of cytokines may not be through its direct action on the NF-kappa B transactivation.

Antigens, Polyomavirus Transforming↗
PubMed1999

Effects of hepatocyte growth factor (HGF) and activin A on the morphogenesis of rat submandibular gland-derived epithelial cells in serum-free collagen gel culture.

To study the mechanisms of morphogenesis in salivary gland regeneration, we have established the RSMG-1 cell line derived from submandibular gland (SMG) of 10-wk-old Wistar female rats in serum-free culture. Our finding that RSMG-1 cells originated from duct cells was based on morphology and immunohistochemical results. In three-dimensional serum-free collagen gel culture, HGF induced branching morphogenesis of RSMG-1 cells. Histological examination revealed that HGF-induced branching structure exhibited well-formed lumina. This morphology closely resembles that found in vivo. The cells also expressed activin A. Exogenously added activin A at a high concentration reduced HGF-induced branching morphogenesis. These findings suggest that the morphogenesis of the salivary gland is modulated by HGF and activin A. Our results show that the RSMG-1 cell line may be useful in studies of salivary gland regeneration.

Activins↗
PubMed1999

Central nervous system symptoms in patients with Behçet disease receiving cyclosporine therapy.

OBJECTIVE: To investigate the association between the development of central nervous system (CNS) symptoms in patients with Behçet disease and medical therapy. DESIGN: Retrospective cohort study. PARTICIPANTS: A total of 317 patients with Behçet disease with ocular complications who visited Hokkaido University Hospital, Sapporo, Japan, between 1978 and 1994. MAIN OUTCOME MEASURES: The incidence of CNS symptoms in different medical therapies. RESULTS: Twenty-one (6.6%) of the 317 patients developed CNS symptoms, namely neuro-Behçet disease. Of the 21 patients, 12 were undergoing cyclosporine therapy. Of the 47 patients who underwent cyclosporine therapy, 12 (25.5%) developed CNS symptoms, whereas only 9 (3.3%) of 270 patients who did not undergo cyclosporine therapy developed CNS symptoms. CONCLUSIONS: Cyclosporine in the treatment of Behçet disease appears to cause neurotoxicity or to accelerate the development of CNS symptoms. Thus, neurologic complications appear to represent a major side effect of cyclosporine in the treatment of patients with Behçet disease.

Adult↗
PubMed1999

Kallikrein-kinin in infection and cancer.

This review article describes the mechanism of enhancement of vascular permeability in infectious disease and cancer. This phenomenon is primarily mediated by bradykinin, nitric oxide and other unique vascular mediators. They are highly intermingled with each other in these disease states. Furthermore, these mediators are elicited in various in vivo settings most frequently induced by bacterial proteases, and indirect or direct activation of kallikrein-kinin cascade at one or more steps. The key steps involve bacterial proteases or cellular components including lipopolysaccharides. Thus, the use of appropriate protease inhibitors or antagonists, or scavengers in the case of nitric oxide, superoxide or peroxynitrite, are anticipated to attenuate the clinical manifestation induced by such mediators. It also explained that fluid accumulation in ascitic or pleural compartments in the case of carcinomatosis in terminal cancer patients can be largely attributed to bradykinin or related mechanism. Systemic bacterial dissemination is also facilitated by bradykinin, or suppressed by kinin antagonists as well as by the inhibition of kinin production, respectively. Thus, control of the level of such vascular mediators appears important both in infectious disease and in cancer. alpha1-Protease inhibitor, which inhibits neutrophil elastase, is inactivated by oxidative metabolites such as superoxide and peroxynitrite, and this effect activates matrix metalloproteinases. This indicates that oxidative stress activates proteolytic potential, and thus accelerates the degenerative process upon infection.

Animals↗