Biomedical subjects

T Oda

Publications and source records attributed to T Oda.

At least 127 records · Page 7Linked to original sources

PubMed1999

The EAT/mcl-1 gene, an inhibitor of apoptosis, is up-regulated in the early stage of acute myocardial infarction.

EAT/mcl-1 (EAT), a bcl-2-related immediate early gene, is up-regulated at an early stage of differentiation of human embryonal carcinoma cells. Recent studies have revealed that EAT inhibits apoptosis both in vitro and in vivo. In the present study, we demonstrated that the EAT gene was up-regulated in the early stage of rat myocardial infarction. This pattern of up-regulation was apparently different from that of another immediate early gene, c-fos. EAT, an anti-apoptotic molecule, was strongly up-regulated in the non-ischemic region. In contrast, the expression of c-fos was induced in both ischemic and non-ischemic regions, and was higher in the ischemic region. Apoptosis of cardiomyocytes is currently thought to significantly contribute to acute myocardial infarction. We detected cardiomyocyte apoptosis by gel electrophoresis of genomic DNA and in situ nick end labeling in the ischemic region, but not in the non-ischemic region. As an inhibitor of apoptosis, EAT may play a role in the protection of cardiomyocytes in the early stage of acute myocardial infarction.

Animals↗

PubMed1999

Flux of the L-serine metabolism in rat liver. The predominant contribution of serine dehydratase.

L-Serine metabolism in rat liver was investigated, focusing on the relative contributions of the three pathways, one initiated by L-serine dehydratase (SDH), another by serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT), and the other involving serine hydroxymethyltransferase and the mitochondrial glycine cleavage enzyme system (GCS). Because serine hydroxymethyltransferase is responsible for the interconversion between serine and glycine, SDH, SPT/AGT, and GCS were considered to be the metabolic exits of the serine-glycine pool. In vitro, flux through SDH was predominant in both 24-h starved and glucagon-treated rats. Flux through SPT/AGT was enhanced by glucagon administration, but even after the induction, its contribution under quasi-physiological conditions (1 mM L-serine and 0.25 mM pyruvate) was about (1)/(10) of that through SDH. Flux through GCS accounted for only several percent of the amount of L-serine metabolized. Relative contributions of SDH and SPT/AGT to gluconeogenesis from L-serine were evaluated in vivo based on the principle that 3H at the 3 position of L-serine is mostly removed in the SDH pathway, whereas it is largely retained in the SPT/AGT pathway. The results showed that SPT/AGT contributed only 10-20% even after the enhancement of its activity by glucagon. These results suggested that SDH is the major metabolic exit of L-serine in rat liver.

Adenosine Triphosphate↗

PubMed1999

Synthesis of novel 2-benzothiopyran and 3-benzothiepin derivatives and their stimulatory effect on bone formation.

In a search for therapeutic agents for the treatment of osteoporosis and bone fracture, we found that 2-benzothiopyran-1-carboxamide derivatives 1, derived from ipriflavone as a lead compound, increase cellular alkaline phosphatase activity in cultures of rat bone marrow stromal cells. Further modification of 1 has led to the discovery of more potent 3-benzothiepin-2-carboxamide derivatives 2. Of these, 3-benzothiepin derivatives bearing a 4-(dialkoxyphosphorylmethyl)phenyl group on the 2-carboxamide moiety such as 2h and 2q exhibited significant improvement of activity compared to ipriflavone. Asymmetric synthesis of 2h and 2q revealed that the (-)-isomers possessed activities superior to those of the (+)-isomers. Further evaluation of these compounds using the mouse osteoblastic cell line MC3T3-E1 revealed that (-)-2q enhanced the effect of bone morphogenetic protein. In addition, application of a sustained-release agent containing 2q increased the area of newly formed bone in a rat skull defect model. Based on these findings, (-)-2q was selected for further investigation as a new drug stimulating bone formation. Synthesis and structure-activity relationships for this novel series of 2-benzothiopyran and 3-benzothiepin derivatives are detailed.

3T3 Cells↗

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

Acute portal hypertension increases ileal vulnerability to platelet-activating factor in rats.

BACKGROUND: Patients with portal hypertension can easily develop sepsis of enteric origin after suffering severe trauma and hemorrhagic shock. Platelet-activating factor (PAF) is one of the key mediators of such stress. The aim of this study was to investigate whether portal hypertension increases the vulnerability of the ileum to PAF. MATERIALS AND METHODS: Seven days after surgery, PAF (1.5 microg/kg) was intravenously injected into portal stenosis (PS) rats and sham-operated rats. The levels of tumor necrosis factor-alpha (TNF-alpha), cytokine-induced neutrophil chemoattractant (CINC), and endotoxin in portal plasma were determined. The levels of PAF receptor (PAFR), TNF-alpha, and CINC mRNA in the ileum were also investigated. RESULTS: After PAF administration, PS rats showed (1) significantly higher portal plasma levels of TNF-alpha, CINC, and endotoxin; (2) higher histological damage scores in the ileum; (3) more infiltrating neutrophils in the ileum; and (4) a significantly higher mortality rate than sham-operated rats (P < 0.01). However, PAFR mRNA levels were similar in the two groups. The CINC mRNA level in the ileum of PS rats was increased from 1 to 4 h after PAF administration, while that of the sham-operated rats was transiently increased at 1 h. CONCLUSIONS: Portal hypertension increases the vulnerability of the ileum to PAF. These findings suggest that conditions which causes PAF production may be dangerous in patients with portal hypertension.

Acute Disease↗

PubMed1999

Inhibitory effect of milrinone on cytokine production after cardiopulmonary bypass.

BACKGROUND: It has been suggested that cyclic adenosine monophosphate-elevating agents suppress cytokine production. To evaluate the effects of milrinone, a phosphodiesterase III inhibitor, on cytokine production after cardiopulmonary bypass, we conducted a prospective randomized study. METHODS: Twenty-four patients undergoing coronary artery bypass grafting were randomized to receive either milrinone treatment (milrinone, n = 12) or no milrinone treatment (control, n = 12). Administration of milrinone (0.5 microg x kg(-1) x min(-1)) was started after induction of anesthesia and was continued for 24 hours. Blood samples for determination of plasma cyclic adenosine monophosphate, tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, and interleukin-8 levels were collected perioperatively. RESULTS: No significant differences were observed in tumor necrosis factor-alpha and interleukin-8 levels between the groups. Interleukin-1beta and interleukin-6 levels after cardiopulmonary bypass were significantly (p < 0.05) lower in the milrinone group than in the control group. Plasma levels of cyclic adenosine monophosphate increased significantly (p < 0.05) after the administration of milrinone and the levels correlated inversely (r = -0.55, p < 0.01) with interleukin-6 levels. CONCLUSIONS: The results indicate that milrinone suppresses cytokine production by elevating cyclic adenosine monophosphate levels in patients undergoing cardiopulmonary bypass. With its positive inotropic and vasodilator activities, milrinone may have antiinflammatory effects.

Aged↗

PubMed1999

Spinal intramedullary ependymal cyst: a case report.

BACKGROUND: Spinal intramedullary ependymal cysts are extremely rare. Only seven pathologically proven cases have been reported in the literature. METHOD: We present an 18-month-old female with thoracic spinal intramedullary ependymal cyst that was diagnosed pathologically. RESULTS: Histological diagnosis was made by light microscopy after immunostaining. After partially removing the cyst wall and establishing communication between the cyst and the subarachnoid space, the patient improved neurologically. CONCLUSIONS: For spinal intramedullary ependymal cyst we recommend diagnosis by MR imaging without myelography, then enucleation of the cyst, if possible. Otherwise, we remove the cyst wall as much as possible and create adequate communication between the cyst and the subarachnoid space.

Cysts↗

PubMed1999

Malignant fibrous histiocytoma of the spermatic cord: a case report.

We present a case of malignant fibrous histiocytoma of the spermatic cord. An 86-year-old man was admitted to the hospital with a right painless scrotal mass. Under the diagnosis of a testicular tumor, right radical orchiectomy was performed. Grossly, the tumor firmly adhered to the spermatic cord. The right testis and epididymis were normal. The histologic diagnosis was malignant fibrous histiocytoma. There was local recurrence 2 months after surgery. The recurrent tumor was resected with the surrounding soft tissue, but the patient died 5 months after the initial operation.

Aged↗

PubMed1999

Recovery from lymphocytopenia following extracorporeal circulation: simple indicator to assess surgical stress.

This study investigated whether the lymphocyte count is a useful indicator to assess surgical damage following extracorporeal bypass. In Study 1, to investigate the correlation between extracorporeal circulating time (ECCT) and lymphocyte counts, 40 elective CABG patients were studied retrospectively. The lymphocyte recovery ratio (LRR), which represented the actual lymphocyte count divided by the preoperative lymphocyte count, was determined preoperatively, and on postoperative day (POD) 1, POD 3, and POD 5. In Study 2, the correlation between the interleukin-8 (IL-8) level and LRR was examined prospectively in elective CABG patients (n = 20). We measured the LRR and serum IL-8 levels preoperatively and during extracorporeal circulation (ECC) at 5 min, at the end of ECC, and 1, 3, and 12 h following ECC termination. Study 1 showed that the LRR decreased until POD 1 and gradually increased thereafter. The LRR had a negative correlation with the ECCT. In Study 2, the IL-8 level demonstrated a time course opposite to that of the LRR; it increased until 3 h after ECC termination and declined thereafter. There was a significant negative correlation between the LRR on POD 3 and the IL-8 level at 3 h after ECC termination. In summary, long-term ECC induced significant and prolonged lymphocytopenia. The LRR had a negative correlation with IL-8. These results indicated that the LRR may represent the degree of surgical stress following ECC; therefore, the counting of lymphocytes can be a quite useful bedside monitor to assess surgical damage and prognosis.

Coronary Artery Bypass↗

PubMed1999

Analysis of p53 gene mutations in Helicobacter pylori-associated gastritis mucosa in endoscopic biopsy specimens.

BACKGROUND: No previous report has shown the relationship between Helicobacter pylori infection and a direct sequence analysis of p53 gene mutation in a biopsy sample of human gastric mucosa. METHODS: A total of 60 endoscopic biopsies samples (21 patients with H. pylori-positive gastritis and 9 patients with H. pylori-negative gastritis), including antral mucosa and corpus mucosa, were used in this study. Direct DNA sequencing of exons 5, 6, 7, and 8 of the p53 gene was performed by the dyedeoxy terminator method. RESULTS: Mutations in the p53 gene were identified in non-hot spot codons in exon 7 and 8 in 11 of 21 samples (52.4%) from H. pylori-positive gastritis patients. There was no mutation in H. pylori-negative gastritis patients. CONCLUSIONS: This finding shows that H. pylori infection can induce p53 point mutations and appears to be involved in the pathway leading to dysplasia or carcinoma.

Adult↗

PubMed1999

Effect of the hemolytic lectin CEL-III from Holothuroidea Cucumaria echinata on the ANS fluorescence responses in sensitive MDCK and resistant CHO cells.

The addition of CEL-III to sensitive MDCK cells preincubated with 8-anilino-1-naphthalenesulfonate (ANS) caused an increase in the fluorescence intensity of the probe. The increase in the ANS fluorescence caused by CEL-III was Ca2+-dependent and strongly inhibited by 0.1 M lactose, indicating that Ca2+-dependent binding of CEL-III to specific carbohydrate receptors on the plasma membrane is responsible for this phenomenon. In contrast, no significant effect of CEL-III on the ANS fluorescence was observed in CHO cells, which are highly resistant to CEL-III cytotoxicity. In MDCK cells, energy transfer from tryptophan residues to bound ANS molecules was observed in the presence of CEL-III, but not in CHO cells. Furthermore, the amount of ANS bound to MDCK cells increased as the concentration of CEL-III increased. Therefore, a simple interpretation is that the CEL-III-induced increase in ANS fluorescence is attributable to an increase of the hydrophobic region in the plasma membrane where ANS could bind. Immunoblotting analysis of proteins from cells treated with CEL-III indicated that CEL-III oligomers were irreversibly bound to the cells, and the amount of oligomer bound to MDCK cells was much greater than that bound to CHO cells under any conditions tested. The oligomerization may be accompanied by an enhancement of the hydrophobicity of CEL-III molecules, which in turn provides new ANS-binding sites. The difference in susceptibility of MDCK and CHO cells to CEL-III cytotoxicity may be due to a difference in oligomerization of bound CEL-III.

Anilino Naphthalenesulfonates↗

PubMed1999

Specific efflux of glutathione from the basolateral membrane domain in polarized MDCK cells during ricin-induced apoptosis.

Although the depletion of reduced glutathione (GSH) has been observed in a variety of apoptotic systems, little is known about the mechanism of GSH depletion. In this study we used polarized MDCK cells to study the GSH flux during ricin-induced apoptosis. Here we report that the specific accumulation of GSH occurred in the basolateral medium during ricin treatment with similar kinetics to in apoptotic changes such as an increase in caspase-3 like activity and DNA fragmentation, while there was no significant increase in the GSH level in apical medium. These results suggest that GSH efflux occurred through a GSH-specific channel or transporter located in the basolateral membrane domain of polarized MDCK cells undergoing apoptosis. Treatment with other protein toxins such as modeccin, Pseudomonas toxin, and diphtheria toxin, which can induce apoptotic cell death, also resulted in selective GSH efflux from the basolateral side. Thus, GSH efflux through a specific transporter may be a common step of apoptosis induced by these toxins, while these toxins have different intoxication mechanisms leading to protein synthesis inhibition. Pretreatment of cells with Z-Asp-CH(2)-DCB, a caspase family inhibitor, inhibited ricin-induced basolateral GSH efflux as well as DNA fragmentation, suggesting that the activation of caspases, i.e. those that are inhibited by Z-Asp-CH(2)-DCB, is implicated in the opening of the GSH transporter.

Animals↗

PubMed1999

Effects of OK-432 on the proliferation and cytotoxicity of lymphokine-activated killer (LAK) cells.

We studied the effect of a streptococcal preparation, OK-432, on the cytotoxicity and the proliferation of lymphokine-activated killer (LAK) cells for use in adoptive immunotherapy. Peripheral blood mononuclear cells (PBMC) were derived from healthy donors and patients with malignant brain tumors. We divided PBMC into two groups; these cells then were stimulated with interleukin-2 in the presence or absence of OK-432. OK-432 was added only in the initial 3 days during the 3-week midterm culture period. Then, we compared OK-432-stimulated LAK (OK-LAK) cells with standard LAK (sLAK) cells in terms of their rate of proliferation and cytotoxicity. OK-LAK cells proliferated more rapidly than sLAK cells. The cytotoxicity of OK-LAK cells increased, whereas that of sLAK cells decreased. We also investigated the phenotypic differences between these two types of LAK cells and found that, on day 21, the OK-LAK cells consisted mostly of CD3-CD56+ NK cells, whereas the sLAK cells consisted mostly of CD3+CD56- T cells. The difference in their level of cytotoxic potential might be explained by the difference of predominant phenotype.

Antigens, CD↗

PubMed1999

Viral hepatitis and hepatocellular carcinoma prevention strategy in Japan.

The study of human hepatitis, particularly in Asia, where the incidence rate has been the highest in the world, has contributed greatly to the understanding of carcinogenesis of the liver and related diseases. In this article, the history of research on hepatitis viruses and hepatocellular carcinoma (HCC) and the successful prevention of vertical transmission of hepatitis B virus (HBV) in Japan are reviewed, focusing on the studies that resulted in the identification of vertical transmission of HBV infection and the association of HBV-sustained infection and HCC. The vaccination trials for preventing HBV vertical transmission and the fruitful outcome of the nationwide vaccination strategy in Japan, on the basis of "selective" immunization by using anti-HBs immunoglobulin (HBIG) and HB vaccine, are highlighted. Ongoing studies on the mechanisms underlying hepatocarcinogenesis induced by viruses, e.g., the roles of viral proteins and inflammation, are also reviewed, and prospects for the control of HCC are discussed.

Carcinoma, Hepatocellular↗

PubMed1999

Oncogenic role of Epstein-Barr virus-encoded RNAs in Burkitt's lymphoma cell line Akata.

Our previous reports indicated that Epstein-Barr virus (EBV) contributes to the malignant phenotype and resistance to apoptosis in Burkitt's lymphoma (BL) cell line Akata (N. Shimizu, A. Tanabe-Tochikura, Y. Kuroiwa, and K. Takada, J. Virol. 68:6069-6073, 1994; J. Komano, M. Sugiura, and K. Takada, J. Virol. 72:9150-9156, 1998). Here we report that the EBV-encoded small RNAs (EBERs) are responsible for these phenotypes. Transfection of the EBER genes into EBV-negative Akata clones restored the capacity for growth in soft agar, tumorigenicity in SCID mice, resistance to apoptotic inducers, and upregulated expression of bcl-2 oncoprotein that were originally retained in parental EBV-positive Akata cells and lost in EBV-negative subclones. This is the first report which provides evidence that virus-encoded RNAs (EBERs) have oncogenic functions in BL cells.

Animals↗

PubMed1999

Epstein-Barr virus promotes epithelial cell growth in the absence of EBNA2 and LMP1 expression.

We attempted to infect primary gastric epithelia (PGE) with recombinant Epstein-Barr virus (EBV) carrying a selectable marker that made it possible to select EBV-infected cells. Cells dually positive for EBV-determined nuclear antigen (EBNA) and cytokeratin were detected in 3 of 21 primary cultures after 3 days of EBV inoculation. From one culture, EBV-infected cell clones were repeatedly obtained at a frequency of 3 to 5 cell clones per 10(6) cells. EBV-infected clones had enhanced population doubling and grew to attain a highly increased saturation density, together with acquisition of marked anchorage independence. The infected clones retained the ultrastructural morphology characteristic of gastric mucosal epithelium and have been growing stably for more than 18 months (corresponding to at least 300 generations) so far, in clear contrast to the parental PGE cells, which ceased growth after 60 generations. The p53 gene of the parental PGE cells was found to be overexpressed, perhaps thereby conferring the basal potential for long-term survival in vitro. Moreover, EBV infection accelerated, to a significant extent, the growth rate and agar clonability of NU-GC-3 cells, an established EBV-negative but EBV-susceptible human gastric carcinoma cell line. Both EBV-converted PGE and NU-GC-3 clones, like EBV-positive gastric carcinoma biopsy specimens, expressed a restricted set of EBV latent infection genes characterized by the absence of EBNA2 and latent membrane protein 1 (LMP1) expression. These results indicate that EBV infection causes a transformed phenotype on PGE in the setting of possible unregulated cell cycling and renders even established gastric carcinoma cells more malignant via a limited spectrum of viral latent-gene expression. This study may reflect an in vivo scenario illustrating multiphasic involvement of EBV in carcinogenesis of gastric or other epithelial cancers.

Cell Division↗

PubMed1999

Degradation of overexpressed wild-type and mutant uricase proteins in cultured cells.

Wild-type and mutated urate oxidase (UO) proteins were overexpressed in Cos-1 and HEK293 cells and were analyzed by Western blotting and several morphological methods. By immunoelectron microscopy, wild-type UO formed large aggregates in the cytoplasm and nucleoplasm and exhibited a crystalloid structure. Mutated UO (UOdC), from which 28 amino acids, including peroxisomal targeting signal at the C-terminus, were deleted, formed dispersed aggregates in the cytoplasm and nucleus. Chimeric UO (MUOdC), which was made by addition of the mitochondrial targeting signal of serine:pyruvate/glyoxylate aminotransferase to the N-terminus of UOdC, attached to ER to form a complicated MUOdC-ER complex. These three structures were immunostained for ubiquitin- and p32-subunits of proteasomes. Western blotting showed strong signal for UO and UOdC but very weak signal for MUOdC. The results suggest that overexpressed UO and UOdC accumulate in the cells because their synthesis rate is higher than the degradation rate, whereas MUOdC forming a complex with ER is degraded very rapidly. The ubiquitin-proteasome pathway may be involved in the degradation of these proteins.

Animals↗

PubMed1999

A one-step enzyme-linked immunosorbent assay for a novel osteoblast differentiation-promoting compound, TAK-778 in serum.

TAK-778, ((2R,4S)-(-)-N-[(4-diethoxyphosphorylmethyl)phenyl]- 1,2,4,5-tetrahydro-4-methyl-7,8-methylenedioxy-5-oxo-3-benzothiepin-2- carboxamide), is a novel osteoblast differentiation-promoting compound, and its sustained-release formulation is expected to be clinically used for the enhancement of fracture healing. To date, TAK-778 levels in serum have been measured using conventional reverse-phase HPLC with inferior sensitivity and time-consuming procedures. We have produced polyclonal antibodies against TAK-778 by using one of its derivatives coupled with a carrier protein, and developed a one-step ELISA for the determination of TAK-778 in serum. The antibodies had minimal cross-reactivities to the biologically inactive metabolites including the oxidized-form (0.36%) and the cleavaged-form (0.00083%). The competitive ELISA was accomplished within three hours with a detection limit of 0.5 ng/ml serum, and the coefficients of variations for samples ranging from 1 ng/ml to 80 ng/ml were 1.1-4.4% in an intra-assay and 3.1-9.6% in an inter-assay. The present ELISA is so rapid, sensitive and selective for TAK-778 that it could be conveniently used in a clinical field for the determination of many serum specimens.

Animals↗