Search PubMed⌕ Search

Biomedical subjects

M Monden

Publications and source records attributed to M Monden.

At least 307 records · Page 17Linked to original sources
PubMed1995

Shear stress induces expression of CNP gene in human endothelial cells.

To elucidate the effect of blood flow on gene transcription of C-type natriuretic peptide (CNP), human umbilical vein endothelial cells were exposed to shear stress in a cone-plate viscometer. Expression of CNP mRNA, evaluated by reverse transcription-polymerase chain reaction, was markedly increased by exposure to shear stress of 24 dyne/cm2 at 3 h. The CNP mRNA level was maintained until 12 h. Thus, the present study demonstrated for the first time that shear stress induces expression of CNP gene in human endothelial cells.

Atrial Natriuretic Factor↗
PubMed1995

Subcellular localization of the APC protein: immunoelectron microscopic study of the association of the APC protein with catenin.

Mutations in the APC gene are linked to the development of sporadic colorectal tumors as well as to familial adenomatous polyposis. Recently, the APC protein was reported to associated with catenins, proteins that bind to the cell adhesion molecule E-cadherin. In the present study, we examined the distribution and localization of the APC protein and alpha -catenin in the normal mouse intestine by light and immunoelectron microscopy using specific antibodies. The APC protein was found to be localized in microvilli and in the apical and lateral cytoplasm of the epithelial cells, whereas alpha-catenin was detected only in the lateral cytoplasm. Double-labeling immunoelectron microscopy showed colocalization of the APC protein with alpha-catenin in the lateral cytoplasm, especially along the lateral plasma membrane, although a certain portion of the APC protein in this region was distributed independently of alpha-catenin. These results suggest that a portion of the APC protein localized in the lateral cytoplasm of intestinal epithelial cells functions in cooperation with catenins, whereas the APC protein in microvilli and in the apical cytoplasm has other functions independent of catenins.

Adenomatous Polyposis Coli Protein↗
PubMed1995

Autocatalytic inactivation of lysosomal cathepsins is associated with inhibition of protein breakdown by insulin-like growth factor-1 (IGF-1) in myotubes.

Protein breakdown was monitored in C2C12 myotubes as the rate of release of radioactivity after prelabeling cell protein with [3H] tyrosine. IGF-1 (13 nM) and insulin (100 nM) prolonged the half-life of long-lived proteins. Enzymatic activities of cathepsins B and B+L were inhibited by the addition of IGF-1 or insulin. Immunoblotting of cathepsins B and L revealed extensive degradation of heavy chain forms by IGF-1. However, neither expression of cathepsins B and L genes nor expression of cystatin beta, an intrinsic inhibitor for cathepsins, was influenced. The addition of E-64, L-3-carboxy-trans-2,3-epoxypropionyl-leucylamide-(4-guanidin o) butane, a inhibitor of cathepsins B and L, increased protein contents of heavy chains of cathepsins B and L in the IGF-1 treated cells. Inhibition of protein breakdown by IGF-1 is mediated by autocatalytic inactivation of lysosomal cathepsins B and L.

Analysis of Variance↗
PubMed1995

Isolation of a candidate tumor suppressor gene on chromosome 8p21.3-p22 that is homologous to an extracellular domain of the PDGF receptor beta gene.

We have isolated a candidate tumor suppressor gene from a 600-kb region on chromosome 8p21.3-p22 that is commonly deleted in sporadic hepatocellular carcinomas (HCC), colorectal cancers (CRC), and non-small cell lung cancers (NSCLC). As this gene encodes a protein of 375 amino acids that bears significant sequence similarity to the extracellular (ligand-binding domain of platelet-derived growth factor receptor beta, we have designated it PRLTS (PDGF-receptor beta-like tumor suppressor). Structural rearrangement involving this gene was found in a sporadic NSCLC. In addition, somatic missense and frame-shift mutations were found in two HCCs and one CRC. These findings indicate that inactivation of the PRLTS gene may play a significant role in development of some carcinomas.

Amino Acid Sequence↗
PubMed1995

Muscle undergoes atrophy in association with increase of lysosomal cathepsin activity in interleukin-6 transgenic mouse.

Interleukin(IL)-6 transgenic mice were produced by microinjection of human IL-6 cDNA fused with H-2Ld promoter into the pronucleus of fertilized eggs from C57BL/6J mice. At 16 weeks old, the gastrocnemius muscles of the IL-6 transgenic mice became atrophic as compared to those of the normal mice, while the body weights increased significantly. The activities and mRNA levels of lysosomal cathepsins B and L were increased in the muscles of the transgenic mice. Immunohistochemical study on the muscles showed increased staining of both cathepsins B and L in the transgenic mice. IL-6 is responsible for enhanced muscle catabolism by activating the lysosomal cathepsin (B and L) system.

Animals↗
PubMed1995

Deletion mapping of the long arm of chromosome 22 in human meningiomas.

Cytogenetic and molecular genetic analyses have shown that a tumor-suppressor gene for human meningioma is located on the long arm of chromosome 22. Recently, somatic mutations of the NF2 gene have been identified in sporadic meningiomas. However, tumorigenesis of certain cases of meningioma cannot be fully explained by inactivation of the NF2 gene alone. Thus, to obtain some indication as to the existence of another tumor-suppressor gene, it seemed important to re-examine the loss of heterozygosity (LOH) on 22q in sporadic meningioma. A total of 46 sporadic meningiomas was examined for LOH at 20 loci on 22q. LOH was observed in 29 tumors (63%), of which 13 (28%) showed different patterns of a partial loss of 22q. However, the NF2 locus was retained in one tumor that lost a more distal part of 22q. Moreover, 27 of the 28 tumors which showed LOH at the NF2 locus also lost alleles at more telomeric loci. These results raise the possibility that another tumor-suppressor gene for meningioma may exist on 22q and that its localization may be distal to the D22S102 locus.

Chromosome Deletion↗
PubMed1995

Involvement of protein phosphatase-1 in cytoskeletal organization of cultured endothelial cells.

The phosphorylation and dephosphorylation of cytoskeletal proteins regulate the shape of eukaryotic cells. To elucidate the role of serine/threonine protein phosphatases (PP) in this process, we studied the effects of calyculin A (CLA), a potent and specific inhibitor of protein phosphatases 1 (PP-1) and 2A (PP-2A) on the cytoskeletal structure of cultured human umbilical vein endothelial cells (HUVECs). The addition of CLA (5 min) caused marked alterations in cell morphology, such as cell constriction and bleb formation. Microtubules and F-actin were reorganized, becoming markedly condensed around the nucleus. Although the fluorescence intensity of phosphoamino acids was not significantly different according to immunocytochemistry between cells with and without CLA, polypeptides of 135, 140, 158, and 175 kDa were specifically phosphorylated on serine and/or threonine residues. There was no significant effect on tyrosine residues. The effects of CLA on cytoskeletal changes and protein phosphorylation were almost completely inhibited by the non-selective kinase inhibitor, K-252a. The effect of CLA on cell morphology was at least 100 times more potent than that of okadaic acid, consistent with the inhibitory potency against PP-1. The catalytic subunit of PP-1 was also identified in HUVECs by Western blotting with its monoclonal antibody antibody. These results suggest that PP-1 is closely involved in sustaining the normal structure of the cytoskeleton.

Actins↗
PubMed1995

PGI2 analogue, sodium beraprost, suppresses superoxide generation in human neutrophils by inhibiting p47phox phosphorylation.

Sodium beraprost, a newly synthesized PGI2 analogue inhibited in a dose-dependent manner formyl-methionyl-leucyl-phenylalanine (fMLP) induced superoxide generation of human neutrophils, but it had no effect on the superoxide synthesis by phorbol myristate acetate (PMA) or A23187. Sodium beraprost inhibited Ca2+ influx in fMLP stimulated neutrophils employing fluorometry and confocal microscopy. These findings suggested that the inhibitory effect of sodium beraprost on fMLP induced superoxide generation was due to suppression of Ca2+ influx. To examine the relationship between the effect of sodium beraprost and phosphorylation of p47phox (the 47kDa cytosolic phagocyte oxidase factor), immuno-precipitation of p47phox and western blotting for phospho-amino acids were performed. Phosphorylation of serine residues of p47phox induced by fMLP was reduced in the presence of sodium beraprost in a dose-dependent manner. The reduction in phosphorylation was accompanied by a reduction in p47phox and p67phox translocation to the plasma membrane and superoxide generation. These findings suggested that p47phox phosphorylation was necessary for translocation and superoxide generation in fMLP activated neutrophils, and that p47phox phosphorylation was regulated by a Ca2+ dependent mechanism. These observations suggested that sodium beraprost inhibited fMLP induced superoxide generation of human neutrophils by the inhibition of p47phox phosphorylation and translocation by a Ca2+ dependent mechanism.

Calcimycin↗
PubMed1995

Role of micro-chimerism in inducing immunological tolerance by intraportal injection of donor spleen cells in rats.

Recently, we reported that intraportal (IP) injection of donor spleen cells (SPCs) prevented liver allograft rejection. Moreover, we developed a new method using polymerase chain reaction (PCR)-mediated restriction fragment length polymorphism (RFLP) analysis, and demonstrated micro-chimerism (MC) at the DNA level in the spleen 14 days after IP injection. In the present study, the long-term presence of injected allogeneic SPCs was investigated at the cellular level by immunofluorescence staining as well as the DNA level using RFLP analysis. Male ACI (RT1a) rats were used as the donors and Lewis (RT1(1)) rats as the recipients. After DNA preparation from the lymphoid organs, RT1B beta domain 1 region was amplified by PCR, and RFLP analysis was performed with PvuII restriction enzyme. In the immunofluorescence staining, the monoclonal antibody, MN4-91-6, was used to detect the injected donor ACI SPCs in a frozen specimen. We did not detect MC in Lewis rats intravenously injected with 5 x 10(7) ACI SPCs on day 14. On the other hand, stable chimerism in the spleen was observed in intraportally injected rats up to 28 days after injection at not only the DNA level but also the cellular level. No chimerism was detected in other organs (including the thymus, lymph nodes, and liver). In conclusion, the long-term presence of injected allogeneic SPCs in the spleen was demonstrated after IP injection but not after IV injection, and this phenomenon may be one of the mechanisms involved in portal venous immunosuppression.

Animals↗
PubMed1995

A protocol with FK 506 for inducing unresponsiveness to murine islet allografts.

BACKGROUND: The most favorable protocol for transplantation is inducing unresponsiveness before operation by means of nondangerous modalities. This would permit discontinuance of long-term use of immunosuppressants. In this study we developed a potential protocol for inducing unresponsiveness to islet allografts by preoperative donor spleen cell inoculation (DSI) and a single injection of FK 506. METHODS: BALB/c (H-2d) and C57BL/6 (H-2b) mice were used as islet donors and recipients, respectively. The streptozocin-induced diabetic mice that had been given DSI at a dose of 1 x 10(7) or 1 x 10(4) and a single injection of FK 506 (10 mg/kg intramuscularly) at different schedules (on day 1, 3, 5, or 7 relative to DSI on day 0) were subjected to islet allografting on day 10. RESULTS: All islet recipients returned to normoglycemia within a few days with no toxic effect of FK 506 treatment. DSI at a dose of 1 x 10(7) alone led to shortening of the mean survival time to 10.1 +/- 4.1 days, as compared with 13.5 +/- 6.3 days for the untreated animals. In contrast, marked prolongation of graft survival was induced when FK 506 was given on day 3 (> 84 +/- 27.3 days, p < 0.0001) or on day 5 after DSI (> 50.9 +/- 46.0 days, p < 0.05). Five of seven allografts given FK 506 on day 3 and three of seven allografts given FK 506 on day 5 survived indefinitely. Other time schedules of DSI and FK 506 treatment (on day 1 or 7 after DSI) or FK 506 treatment alone had no significant effect on mean survival time. With the same protocol, third-party islet allografts (C3H) were immediately rejected (10.6 +/- 2.6 days). CONCLUSIONS: Prolongation of islet allograft survival was induced by certain doses of DSI and preoperative FK 506 treatment. This modality prevents an adverse effect of FK 506 on grafted islets and can induce unresponsiveness to islet allografts, offering a protocol for successful clinical islet transplantation.

Animals↗
PubMed1995

Coexpression of cdk2/cdc2 and retinoblastoma gene products in colorectal cancer.

The retinoblastoma gene (Rb gene) is a tumour-suppressor gene and its product (pRB) is known to act as a negative regulator of the cell cycle. Although lack of pRB expression resulting from gene alterations is considered to be responsible for the genesis of several human malignancies, increased expression of pRB has been demonstrated in a majority of colorectal cancer cases. In the present study, we investigated the expression of pRB as well as that of its related kinases, cdk2 and cdc2, in colorectal cancer, since these kinases have been reported to phosphorylate and inactivate pRB. Western blot analysis revealed that colorectal cancer expressed higher levels of cdk2 and cdc2 than did normal mucosa and that the ratio of the hyperphosphorylated form of pRB was higher in colorectal cancer. Furthermore, immunohistochemical studies showed that cdk2/cdc2 was expressed exclusively in the cancer cells positive for pRB. These results suggest that an increase in the expression of cdk2/cdc2 in colorectal cancer may have prevented pRB from braking the cell cycle through phosphorylation.

Blotting, Western↗
PubMed1995

Interleukin-6 induces proteolysis by activating intracellular proteases (cathepsins B and L, proteasome) in C2C12 myotubes.

1. A cell culture system of C2C12 myotubes was established as a model of the muscle. With the aid of this model, the half-lives of intracellular proteins as well as the activities and mRNA levels of proteasomes (26S and 20S) and cathepsins (B, L, and H) were examined in the presence of various amounts of cytokines. 2. It was found that 100 units/ml recombinant human interleukin-6 somewhat shortened the half-life of long-lived proteins to 23.79 +/- 1.55 h (control: 25.60 +/- 1.87 h). When 1% fetal bovine serum contained in the culture medium was replaced by 0.5 mg/ml bovine serum albumin, interleukin-6 was more effective since 10 units/ml of interleukin-6 shortened the half-life to 19.09 +/- 2.87 h (control: 22.26 +/- 321 h). Interleukin-6 (100 units/ml) increased the activity of 26S proteasome by 31.5%, of cathepsin B by 53.5% and of cathepsin B+L by 21.3%. These increases occurred in association with an increase in their transcription. 3. On the other hand, 1000 units/ml of recombinant human tumour necrosis factor alpha prolonged the half-life of long-lived proteins while reducing the protease activities of 20S proteasome (-27.1%), cathepsins B (-64.6%) and B+L (-54.9%). 4. These results suggest that interleukin-6 induces degradation of long-lived intracellular proteins by activating both the non-lysosomal (proteasomes) and lysosomal (cathepsins) proteolytic pathways. It is therefore concluded that interleukin-6 is a candidate for a proteolysis-inducing factor in myotubes and may play an important role in the progression of muscle degradation in systemic inflammatory responses induced by sepsis or severe injury.

Animals↗
PubMed1995

Changes of proteasomes and cathepsins activities and their expression during differentiation of C2C12 myoblasts.

C2C12 myoblasts fuse to form multinucleated myotubes and express muscle specific proteins during differentiation. To elucidate developmental regulation of intracellular proteolytic systems, enzymatic activities, protein and mRNA levels of proteasomes (20S and 26S) and lysosomal cathepsins (B, L, and H) were examined. Myoblasts were differentiated fully to myotubes 6 days after starting differentiation. In this developmental process, the 26S proteasome activity decreased, while the 20S proteasome activity increased. Expression of proteasome subunits of 20S (RC2, RC8) and regulatory components of 26S (S4, S7) was down-regulated, though total protein levels of proteasomes showed no remarkable changes. On the other hand, enzymatic activities of cathepsins B and B + L increased in association with an increase of their transcriptional and translational levels. Expression of their specific endogenous inhibitor, cystatin beta, also increased. Maturation of the lysosomal proteolytic system was tightly linked to the differentiation process. These results suggested that signals for differentiation of myoblasts mediate a change of intracellular proteolytic systems, involving up-regulation of lysosomal cathepsins and down-regulation of proteasomes.

Animals↗
PubMed1995

Interleukin 10 reduces mortality from severe peritonitis in mice.

Interleukin 10 (IL-10) is known to suppress the induction of proinflammatory cytokines such as tumor necrosis factor (TNF) and IL-1 and is itself induced by monocytes and macrophages during sepsis. We studied the therapeutic efficacy of IL-10 by testing its effect on the survival rate in the murine cecal ligation-and-puncture (CLP) model. Administration of 1 microgram or more of recombinant murine IL-10 6 h after induction of sepsis decreased lethality in septic mice significantly and also suppressed the elevation of circulating TNF after sepsis. However, treatment with the same dose of IL-10 simultaneously or 6 h before induction of CLP had no effect on survival, and treatment with anti-TNF antibody after induction of CLP had no effect on the survival rate. These data suggest that cytokine modulation with IL-10 is a potential candidate for the treatment of sepsis and sepsis-related multiple organ failure.

Animals↗
PubMed1995

Healing of polytetrafluoroethylene vascular grafts analyzed by anti-smooth muscle myosin heavy chain isoforms.

The purpose of this study was to characterize the cellular contributions to the formation of the pseudointima (PI) using immuno-histochemistry with antibodies to specific smooth muscle myosin isoforms, SM1, SM2, SMemb, and to alpha-smooth muscle actin. The outer wall of polytetrafluoroethylene tube grafts were coated with a 10-microns silicon film except for 5 mm of the midportion and the grafts were implanted into the inferior vena cava of rabbits. The PI in the anastomotic area was mainly formed by dedifferentiation and redifferentiation of medial smooth muscle cells of the host vessel, while PI in the midgraft was formed by differentiation of myofibroblasts into smooth muscle cells in the internodal space.

Animals↗
PubMed1995

Changes in serum granulocyte colony-stimulating factor (G-CSF) and interleukin 6 (IL-6) after surgical intervention.

To evaluate the physiological role of G-CSF following surgery, we measured the serum levels of immunoreactive IL-6 and G-CSF sequentially in nine patients after major elective thoracoabdominal surgery for esophageal carcinoma. Both G-CSF and IL-6 levels reached their maxima at the first postoperative day and decreased thereafter. There was a significant correlation between serum G-CSF (y) and IL-6 (x) levels (y = 3.273x + 3.991; r = 0.787, n = 78, p < 0.001). In the case that developed aspiration pneumonia and ARDS at the second postoperative day, the measured G-CSF level was less than half the predicted value. The relationship between serum G-CSF and IL-6 levels supports the central role of G-CSF as the host defense response modifier and, thus, low G-CSF levels in the circulation is one reason for the immunodeficient state after major surgery.

Aged↗