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T Muramatsu

Publications and source records attributed to T Muramatsu.

At least 145 records · Page 8Linked to original sources
PubMed2000

Isolated ricin B-chain-mediated apoptosis in U937 cells.

We have previously reported that ricin, a toxic lectin that inhibits protein synthesis induced apoptotic cell death. In this study, we have found that isolated ricin CM-B-chain, which has no effect on cellular protein synthesis, induced DNA fragmentation in U937 cells in a dose- and time-dependent manner, albeit it required a longer incubation time and higher concentration than those of holotoxin ricin. Z-Asp-CH2-DCB, a caspase family inhibitor and serine protease inhibitor, 3,4-dichloroisocoumarine (DCI) effectively inhibited the CM-B-chain-mediated DNA fragmentation as well as in ricin. Thus, like ricin, multiple proteases with different substrate specificity may also be involved in the CM-B-chain-mediated apoptotic pathway. Furthermore, BFA inhibited both ricin- and CM-B-chain-mediated DNA fragmentation, suggesting an intracellular vesicle transport system through the Golgi complex may be involved in the apoptotic induction by these proteins as a common feature. On the other hand, cycloheximide (CHA) strongly increased the CM-B-chain-mediated DNA fragmentation, but inhibited ricin-mediated DNA fragmentation. The opposite effects of CHA may reflect the difference in the apoptotic mechanism between ricin and CM-B-chain. In conclusion, our results suggest that ricin-B-chain can induce apoptosis through its lectin activity, but the underlying mechanism may be distinct from that of ricin in which the A-chain contributes profoundly to the apoptotic induction.

Apoptosis↗
PubMed2000

Concanavalin A-induced discharge of glycocalyx of raphidophycean flagellates, Chattonella marina and Heterosigma akashiwo.

Chattonella marina and Heterosigma akashiwo, known as red tide phytoplankton, are naturally wall-less and have quite fragile cell structures. In this study, we found that an equilibrium dialysis technique allowed the study of lectin binding to these flagellates. The results suggested that concanavalin A (Con A) binds to these flagellate cells through the specific carbohydrate moieties on the cell surface. Interestingly, the binding of an excess of Con A on the cell surface caused morphological changes concomitant with discharge of glycocalyx, a polysaccharide-containing common structure on the external cell surface of these flagellates. Fluorescent microscopic observation using FITC-labeled Con A (F-Con A) confirmed that F-Con A molecules are localized on the discharged glycocalyx.

Animals↗
PubMed2000

Effects of glutathione-related compounds on increased caspase-3 and caspase-6-like activities in ricin-treated U937 cells.

Both caspase-3 and -6-like activities increased in the cytosolic extract from ricin-treated U937 cells that were inhibited by glutathione disulfide (GSSG) in a dose-dependent manner, but reduced glutathione (GSH) had no effect. Interestingly, caspase-6 like activity was more sensitive to GSSG than caspase-3 like activity. The IC50 of GSSG against caspase-3 and caspase-6 like activities were estimated to be 2.8 mM and 0.8 mM, respectively. Cystine but not cysteine also showed similar inhibitory effect on caspase-3-like activity. The inhibitory effect of GSSG on these caspase-like activities was prevented by the addition of DTT to the assay mixture. These results suggest that an intact disulfide portion of GSSG is required for the effective inhibition of caspase activity.

Apoptosis↗
PubMed2000

Some molecular and inhibitory specifications of a dipeptidyl carboxypeptidase from the polychaete Neanthes virens resembling angiotensin I converting enzyme.

Dipeptidyl carboxypeptidase (DCP) from the polychaete Neanthes virens, resembling mammalian angiotensin I converting enzyme (ACE), was studied to discover some of its molecular and inhibitory properties, as the first evidence of these in a marine invertebrate. Amino acid and carbohydrate contents were analyzed. The N-terminal amino acid sequence of N. virens DCP was (NH2)D-E-E-A-G-R-Q-W-L-A-E-Y-D-L-R-N-Q-T-V-L-. Peptide maps of N. virens DCP from lysyl endopeptidase digestion were different from rabbit p-ACE. The far-ultraviolet circular dichroic spectra of N. virens DCP indicated that the secondary structure of this enzyme seemed to be an alpha-helical structure and was similar to that of rabbit p-ACE, but the near-ultraviolet circular dichroic spectra of N. virens DCP indicated that the aromatic amino acid residue circumambience of this enzyme was different from rabbit p-ACE. The effects of several reagents for chemical modification of amino acids on the activity of N. virens DCP were tested. Arg, Tyr, Glu, and/or Asp, His, Trp, and Met caused loss of the activity. In addition, the IC50 and Ki values for a well-known ACE inhibitor, Val-Tyr, which was a competitive inhibitor of N. virens DCP, were 263 and 20 microM, respectively. These results suggested that N. virens DCP is different from mammalian ACE in the molecular and inhibitory properties, although the same substrate specificity was demonstrated in a previous paper.

Amino Acid Sequence↗
PubMed2000

Specific toxic effect of dinoflagellate Heterocapsa circularisquama on the rotifer Brachionus plicatilis.

Heterocapsa circularisquama (Dinophyceae), a noxious red tide dinoflagellate, is known to have a specifically lethal effect on shellfish, especially bivalves such as pearl oyster (Pinctada fucata), but no detrimental effects of this alga on fishes have not been observed so far. In this study, we found that H. circularisquama was toxic to a microzooplankton, a rotifer (Brachionus plicatilis) in a cell concentration-dependent manner, while the cultured supernatant or ultrasonic ruptured H. circularisquama had no significant toxic effect on the rotifer. Since no such toxic effects on the rotifer were observed in Chattonella marina, Heterosigma akashiwo, or Cochlodinium polykrikoides, other species of harmful red tide plankton, H. circularisquama may have a strictly specific toxic mechanism against the rotifer as well as bivalves.

Animals↗
PubMed2000

Galacturonic-acid-induced increase of superoxide production in red tide phytoplankton Chattonella marina and Heterosigma akashiwo.

Red tide phytoplankton, Chattonella marina and Heterosigma akashiwo, are known to generate superoxide anion (O2-). We found that galacturonic acid (GaLUA) stimulated C. marina and H. akashiwo to generate increased amounts of O2-. Since such effect was not observed in any other monosaccharides tested, our results suggest that the binding of GalUA to specific sites on the flagellate cell surface may induce the increase of 02- production.

Culture Media↗
PubMed2000

Midkine expression in Reed-Sternberg cells of Hodgkin's disease.

Midkine (MK) was originally cloned as a product of a retinoic acid-responsive gene. The rationale for studying MK expression is based on previous reports showing that it transforms 3T3 cells, and that it acts as an autocrine growth factor in Wilm's tumors, and that its overexpression has been associated with worse outcome in bladder carcinoma. Besides bladder carcinoma, its expression was reported in various solid tumors. We investigated the expression of MK protein and/or MK gene in biopsied specimens from 40 patients with primary malignant lymphoma, 21 with Hodgkin's disease (HD) and 19 with non-Hodgkin's lymphoma (NHL). Reed-Sternberg (R-S) cells were stained positive in 10 of 16 HD cases evaluated by immunohistochemical method, whereas 18 of 19 NHL cases did not stain, and one B-cell NHL stained weakly positive. Immunostaining analysis was extended to established cell lines and to normal lymphocytes with or without lectin stimulation or with EB virus transformation. Among hematopoietic cells examined, erythro- or megakaryoblastic leukemia cell lines (K562, MEG-01 and UT7) were positive, while normal lymphocytes (except the EB virus-transformed one) and most myeloid and lymphoid cell lines (except Raji cells) were negative. On the contrary, solid tumor cell lines showed high and strongly positive staining including cell lines derived from of lung gastric, colon, and a pancreatic cancer. Using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), which is suitable for the detection of weakly expressed mRNA, the relative ratio of MK mRNA to beta-actin mRNA of samples was measured and compared in cases where RNA was available. The mean values of relative ratio (MK/beta-actin) of HD were almost twice as those of NHL samples, peripheral blood T cells, and spleen B cells. Our findings showed that MK is expressed in Reed-Sternberg cells of HD, and that MK might play a role in the pathogenesis of HD.

Animals↗
PubMed2000

Alcohol and aldehyde dehydrogenase genotypes in Korsakoff syndrome.

BACKGROUND: Previous studies have suggested a genetic predisposition to the development of Wernicke-Korsakoff syndrome (WKS), a neuropsychiatric syndrome commonly associated with alcoholism; however, little is known about this genetic risk factor. METHODS: To test the hypothesis that altered alcohol or aldehyde regulation is related to the development of WKS, the genetic polymorphisms of aldehyde dehydrogenase-2 (ALDH2) and alcohol dehydrogenase-2 (ADH2) were examined in 47 alcoholic subjects with WKS and compared with those of 342 alcoholic subjects without any WKS symptoms and 175 nonalcoholic controls. RESULTS: Although the frequencies of the ALDH2 genotypes and alleles did not differ significantly between alcoholic subjects with WKS and alcoholics without WKS, the ADH2*1/2*1 genotype and ADH2*1 allele were significantly increased in WKS. CONCLUSIONS: These findings suggest that the ADH2*1/2*1 genotype is a risk factor for the development of WKS in alcoholic patients.

Aged↗
PubMed2000

Inactive aldehyde dehydrogenase 2 worsens glycemic control in patients with type 2 diabetes mellitus who drink low to moderate amounts of alcohol.

BACKGROUND: Alcohol intake can have hypoglycemic or hyperglycemic effects in patients with type 2 diabetes mellitus. The present study was designed to investigate the glycemic control of male patients with diabetes mellitus from the aspect of the genetic status of alcohol metabolism. METHODS: One hundred sixty-three men with type 2 diabetes mellitus were enrolled in the present study. They were all outpatients at the Diabetes Center of Saiseikai Central Hospital. The genotype of the aldehyde dehydrogenase 2 (ALDH2) gene of each patient was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and the patients were divided into those with active or inactive ALDH2 phenotype. We compared the amount of habitual alcohol intake and clinical data that included physical findings and blood chemistry of the patients in the active and inactive ALDH2 groups. The glycemic control of each patient was evaluated by the serum level of HbAlc. RESULTS: Of the 163 patients with type 2 diabetes mellitus, 90 patients had the active ALDH2 phenotype and 73 patients had the inactive ALDH2 phenotype. The mean HbA1c level of the active ALDH2 group was nearly the same as that of the inactive ALDH2 group. However, the HbA1c level of the light-to-moderate drinkers (1-400 g/week) in the inactive ALDH2 group was highest and was significantly higher than the HbA1c level of the light-to-moderate drinkers of the active ALDH2 group. The HbA1c of the patients with diabetic complications was higher than the HbAlc of those without diabetic complications in both the active and inactive ALDH2 groups. However, the HbA1c level of the light-to-moderate drinkers without diabetic complications in the inactive ALDH2 group was significantly higher and the incidence of 24 hr urinary C-peptide was higher than the respective level of the light-to-moderate drinkers without diabetic complications in the active ALDH2 group. CONCLUSIONS: Habitual light-to-moderate alcohol intake worsens glycemic control in diabetic patients who have the inactive ALDH2 phenotype. The data on 24 hr urinary C-peptide level suggested that increased acetaldehyde after light-to-moderate drinking by inactive ALDH2 diabetic patients may increase the HbA1c value by the insulin-resistant condition that resulted in hyperinsulinemia.

Adult↗
PubMed2000

Effect of epinephrine and combination treatment of epinephrine and heat on melanoma cell lines. Study of cytotoxicity and kinetics of 72-kD stress protein.

To elucidate the effect of epinephrine and the combination with heat on malignant cells, using two melanoma cell lines, HM6KO and G361, we have examined the cytotoxicity and induction of 72-kD stress protein (HSP72) after the treatments. After epinephrine treatment, in both cell lines, cell survival rates decreased gradually in a concentration-dependent manner. After the combination treatment, cell survival rates decreased more than those when two treatments were done separately. The cytotoxicity of epinephrine was more enhanced in G361 than in HM6KO by heat. After epinephrine treatment, in both cell lines, the level of HSP72 did not elevate. After combination treatment, in HM6KO, the level of HSP72 were higher than those of heat alone. In G361, the kinetics of HSP72 level was similar to that of heat alone. These results suggest that epinephrine has a cytotoxicity to melanoma cells and the cytotoxicity is enhanced by the combination. In addition, it is probable that epinephrine does not have HSP72 inducibility in HM6KO and G361, and the different kinetics of HSP72 between the cell lines in the combination treatment may play an important role to determine the degree of enhancement.

Adrenergic Agonists↗
PubMed2000

Retinal dysfunction in basigin deficiency.

PURPOSE: To examine the retina of basigin (Bsg) knockout mice by electrophysiological and histologic methods and thereby to determine the possible function of Bsg in phototransduction and retinal development. METHODS: Scotopic and photopic electroretinograms (ERGs) were recorded from 11 wild-type, 12 heterozygous, and 8 homozygous Bsg gene knockout mice of different ages. The retinas were also examined by histologic and immunolabeling methods. RESULTS: Bsg knockout mice of 5 to 41 weeks of age showed a decrease in the amplitude of all components of both the photopic and scotopic ERGs. In contrast, the fundus and the fluorescein fundus angiography and morphology of the retina at the light microscopic level appeared to be normal until 8 weeks of age in Bsg knockout mice. Thereafter, the length of outer segment and outer nuclear layers decreased with increasing age. Immunohistochemical analysis localized Bsg protein in a variety of cells in the retina, especially in the pigment epithelium, the upper outer plexiform layer and the inner segments of photoreceptor cells. CONCLUSIONS: The results demonstrated that both rod and cone function were severely affected from an early age by the targeted disruption of the Bsg gene. In spite of abnormal ERGs, the photoreceptor cells maintained normal morphology up to 8 weeks. Thereafter, the photoreceptor cells degenerated gradually and were almost ablated by 41 weeks.

Animals↗
PubMed2000

Efficacy of directional coronary atherectomy before stent implantation for coronary ostial lesions.

We evaluated stent implantation following directional coronary atherectomy (DCA) for coronary ostial lesions. The subjects were 27 patients (27 lesions) who underwent stent deployment after DCA, and 47 patients (47 lesions) who underwent stent deployment alone as the control group. There were no differences in numbers of lesions with multi-vessel disease, left anterior descending artery lesions, de novo lesions or reference vessel diameters in the two groups. The percent diameter stenosis after stent implantation was lower in the DCA-stent group than in the stent-alone group (9 +/- 10% versus 17 +/- 14%, respectively; p < 0.01). The initial procedural success rate was 92.6% in the DCA-stent group and 91.4% in the stent-alone group. The initial clinical success rate was 100% in the DCA-stent group and 95.7% in the stent-alone group. The restenosis rate was lower in the DCA-stent group (20% versus 43% in the stent-alone group). This study showed that debulking by DCA before stenting is more effective compared to stenting alone.

Aged↗
PubMed1999

Genomic organization and promoter activity of embigin, a member of the immunoglobulin superfamily.

Embigin is a transmembrane glycoprotein belonging to the immunoglobulin superfamily, which is preferentially expressed in early stages of mouse embryogenesis and enhances integrin-mediated cell-substratum adhesion. The mouse embigin gene, which we cloned, spanned more than 50kb, in which nine exons were present. All exons contained protein-coding sequences. Each of the two immunoglobulin domains was encoded by two exons, and the C-proximal half of the second immunoglobulin domain and the transmembrane domain were in the same exon. These features are shared by the basigin gene; together with protein sequence homology, our results defined a family in the immunoglobulin superfamily, to which embigin and basigin both belong. The major transcriptional initiation site of embigin gene was 103 bases upstream from the translation initiation site, as determined by 5' rapid amplification of cDNA ends. A 3kb DNA fragment upstream from the transcriptional initiation site contained three Sp1 binding sites and had a promoter sequence capable of expressing the downstream gene not only in F9 embryonal carcinoma cells which express the gene, but also in L and G401 cells which do not, indicating the presence of a regulatory region outside the 3kb DNA region. Deletion analysis of the 3.5kb DNA fragment revealed that the region between -125 to +1, containing a single Sp1 binding site, is essential for transcription of the embigin gene.

Amino Acid Sequence↗
PubMed1999

Genomic analysis of a murine cell-surface sialomucin, MGC-24/CD164.

MGC-24 is a sialomucin originally found in human gastric carcinoma cells, and in human hematopoietic progenitor cells. In the human, soluble and transmembrane forms of MGC-24 are present, and the transmembrane form has been implicated in adhesion of hematopoietic progenitor cells to marrow stroma cells. In the mouse, we found that only the transmembrane form was expressed in many organs. Northern blotting and in situ hybridization analysis showed that MGC-24 mRNA was widely expressed in various adult and embryonic tissues. The mouse MGC-24 gene, which we isolated, spanned about 12 kb and was comprised of six exons. The transmembrane domain and the cytoplasmic domain were encoded by a single exon; the finding agrees with the absence of an alternatively spliced product of mouse MGC-24. The minimal promoter of mouse MGC-24 was embedded in GC-rich sequences, in which two Sp1 binding motifs were found, but it lacked TATA and CAAT boxes. That the promoter resembles that of house-keeping genes is consistent with the broad expression of mouse MGC-24 mRNA.

Animals↗
PubMed1999

Pattern of expression of beta-defensins in oral squamous cell carcinoma.

Human beta-defensin (hBD)-1 and hBD-2 are antimicrobial peptides that have been detected in certain types of epithelia, including the skin and oral epithelia. It has been suggested that bacterial infection is an important factor in the process of carcinogenesis. The expression of hBDs in oral squamous cell carcinoma (SCC) may be down-regulated. We studied the pattern of expression of hBD-1 and hBD-2 mRNA in oral (SCC) cell lines and in tumor samples obtained from four patients with oral SCC who underwent surgical resection, by reverse transcription-polymerase chain reaction (RT-PCR). Human gingival epithelial (HGE) cells were used as the control. The effect of various inflammatory cytokines on hBD-1 and hBD-2 expression in the HGE cells and SCC cell lines, was also studied. hBD-1 mRNA was detected in the Ca-9, SCC-9 and HSC-4 cell lines, but not in the SAS and KB cell lines. hBD-2 mRNA was detected in all five cell lines. All four tumor samples expressed both hBD-1 and hBD-2 mRNA, although the mRNA level of each protein varied. These results indicate that SCCs in which hBD expression is downregulated, may be susceptible to bacterial infection.

Aged↗
PubMed1999

Physical and functional interactions between Pim-1 kinase and Cdc25A phosphatase. Implications for the Pim-1-mediated activation of the c-Myc signaling pathway.

The pim-1 oncogene encodes a serine/threonine kinase (Pim-1) involved in the transduction of cytokine-triggered mitogenic signals. Pim-1 is unique in that it closely cooperates with c-Myc not only in oncogenesis, but also in apoptosis induction. However, the molecular basis of Pim-1 function remains poorly understood, largely because the downstream effector molecule(s) for Pim-1 kinase has not been identified. Here we provide several lines of evidence that Cdc25A cell cycle phosphatase, a direct transcriptional target for c-Myc, is a substrate for Pim-1 kinase and functions as an effector for Pim-1. We found that Pim-1 physically interacts with Cdc25A both in vitro and in vivo and phosphorylates Cdc25A. We also observed that Pim-1-mediated phosphorylation of Cdc25A increases its phosphatase activity. In addition, wild-type Pim-1, but not kinase-inactive Pim-1, enhanced Cdc25A-mediated cellular transformation and apoptosis. Our results indicate that Cdc25A might be a key molecule that links Pim-1 and c-Myc and that also ties Pim-1-mediated mitogenic signals to cell cycle machinery.

Animals↗
PubMed1999

A receptor-like protein-tyrosine phosphatase PTPzeta/RPTPbeta binds a heparin-binding growth factor midkine. Involvement of arginine 78 of midkine in the high affinity binding to PTPzeta.

Midkine is a 13-kDa heparin-binding growth factor with 45% sequence identity to pleiotrophin. Pleiotrophin has been demonstrated to bind to protein-tyrosine phosphatase zeta (PTPzeta) with high affinity. In this study, we examined the binding of midkine to PTPzeta by solid-phase binding assay. Midkine and pleiotrophin binding to PTPzeta were equally inhibited by soluble pleiotrophin and also by some specific glycosaminoglycans. For both bindings, Scatchard analysis revealed low (3.0 nM) and high (0.58 nM) affinity binding sites. These results suggested that PTPzeta is a common receptor for midkine and pleiotrophin. Midkine is structurally divided into the N- and C-terminal halves, and the latter exhibited full activity for PTPzeta binding and neuronal migration induction. The C-terminal half contains two heparin-binding sites consisting of clusters of basic amino acids, Clusters I and II. A mutation at Arg78 in Cluster I resulted in loss of the high affinity binding and reduced neuronal migration-inducing activity, while mutations at Lys83 and Lys84 in Cluster II showed almost no effect on either activity. Chondroitinase ABC-treated PTPzeta exhibited similar low affinity binding both to the native midkine and midkine mutants at Arg78. These results suggested that Arg78 in midkine plays an essential role in high affinity binding to PTPzeta by interacting with the chondroitin sulfate portion of this receptor.

Animals↗