Biomedical subjects

S Deguchi

Publications and source records attributed to S Deguchi.

At least 19 recordsLinked to original sources

PubMed2005

Intracellular stress transmission through actin stress fiber network in adherent vascular cells.

Intracellular stress transmission through subcellular structural components has been proposed to affect activation of localized mechano-sensing sites such as focal adhesions in adherent cells. Previous studies reported that physiological extracellular forces produced heterogeneous spatial distributions of cytoplasmic strain. However, mechanical signaling pathway involved in intracellular force transmission through basal actin stress fibers (SFs), a mechano-responsive cytoskeletal structure, remains elusive. In the present study, we investigated force balance within the basal SFs of cultured smooth muscle cells and endothelial cells by (i) removing the cell membrane and cytoplasmic constituents except for materials physically attaching to the substrate (i.e., SF-focal adhesion complexities) or (ii) dislodging either mechanically or chemically the cell processes of the cells expressing fluorescent proteins-labeled actin and focal adhesions in order, to examine stress-release-induced deformation of the basal SFs. The result showed that a removal of mechanical restrictions for SFs resulted in a decrease in the length of the remaining SFs, which means SFs bear tension. In addition, a release of the preexisting tension in a single SF was transmitted to another SF physically linked to the former, but not transmitted to the other ones physically independent of the former, suggesting that the prestress is balanced in tensed SF networks. These results support a hypothesis regarding cell structural architecture that physiological extracellular forces can produce in the basal SF network a directional intracellular stress or strain distribution. Therefore, consideration of the coexistence of the directional stretching strain along the axial direction of SFs and the heterogeneous strain in the other cytoplasmic region will be essential for understanding intracellular stress transmission in the adherent cells.

Actins↗

PubMed2005

Evaluation of tension in actin bundle of endothelial cells based on preexisting strain and tensile properties measurements.

Actin bundles in vascular endothelial cells (ECs) play a critical role in transmitting intracellular forces between separate focal adhesion sites. However, quantitative descriptions of tension level in single actin bundles in a physiological condition are still poorly studied. Here, we evaluated magnitude of preexisting tension in a single actin bundle of ECs on the basis of measurements of its preexisting stretching strain and tensile properties. Cultured ECs expressing fluorescently-labeled actin were treated with detergents to extract acin bundles. One end of an actin bundle was then dislodged from the substrate by using a microneedle, resulting in a shortening of the actin bundle due to a release of preexisting tension. Assuming the shortened actin bundle reached its non-stress state, preexisting stretching strain was determined to be 0.24 on average. A tensile test of the dislodged single acin bundle was conducted with a pair of cantilevers to measure the force required for stretching it up to the original length, yielding an estimate of preexisting tension in the actin bundle. The magnitude of the preexisting tension, 4 nN on average, was comparable to previously reported data of the traction force generated by adherent cells at single adhesion sites to keep cell integrity. The Young's modulus of the isolated actin bundle was estimated to be approximately 300 kPa from the tensile tests together with evaluation of average diameter of the isolated actin bundle based on transmission electron microscopy. These data will contribute to better understanding of intracellular stress transmission mechanism in ECs.

Actins↗

PubMed2001

Stable colloidal dispersions of fullerenes in polar organic solvents.

Colloidal dispersions of C60 and C70 were prepared by simply mixing a fullerene solution in a good solvent with a poor polar organic solvent for fullerenes. The process was very easy and fast and the formation of particles with average diameter in the colloidal range was detected immediately after the components were mixed. The formation and the properties of the fullerene particles were studied mainly with dynamic light scattering and high-resolution transmission electron microscopy. The most interesting findings are the long-term colloid stability of the samples in the absence of any stabilizers, the relatively narrow size distribution, and the different average sizes of the particles formed by C60, C70, and their mixtures. The influence of various factors such as fullerene concentration, mixing procedure, solvent properties, and C60/C70 ratio was investigated. It is shown that the smaller particles are formed when the total fullerene concentration in the good solvent is decreased and that the fullerene particles have crystalline structure. The measured negative values for the electrophoretic mobility of the particles suggest that fullerene dispersions in polar organic solvents are stabilized by repulsive electrostatic interactions.

Journal Article↗

PubMed2001

Characterization of 5' flanking region of alpha isoform of rat Ca2+/calmodulin-dependent protein kinase II gene and neuronal cell type specific promoter activity.

The 5' flanking region of the alpha isoform of the rat Ca2+/calmodulin-dependent protein kinase II (alpha CaM kinase II) gene was isolated in 2.3 kbp of genomic sequence. Functional analysis of alpha CaM kinase II promoter deletion mutants fused to a reporter gene in neuroblastoma, including N18TG2, NG108-15, and CAD cells revealed strong transcriptional activity localized 100-145 bp, and a potent silencer 199-275 bp upstream of the transcription start site. The promoter is inactive in non-neuronal cells including BALB/c 3T3, Chinese hamster ovary, HT1080, and C6 glioma cells. These results indicated that the alpha CaM kinase II gene is transcribed from a tissue-specific promoter which is under intense negative control.

Animals↗

PubMed2001

Impaired blood rheology by remnant-like lipoprotein particles: studies in patients with fatty liver disease.

Fatty liver disease (FLD) characterised by a high plasma levels of lipoproteins and remnant-like lipoproteins (RLP) is a risk factor for impaired microvascular blood flow, endothelial cell dysfunction and atherosclerosis. Using an immunoseparation technique with a gel mixture containing human monoclonal antibodies to apo A-I and apo B-100, we separated and measured RLP cholesterol (RLP-C) levels which reflect RLP in patients with FLD (n=20). Whole blood transit time (TT) was determined by a microchannel method (MC-FAN) which allows blood flow to be viewed via a microscope connected to an image display unit. RLP-C levels were higher (P<0.01) in FLD, 15.6 +/- 1.0 mg/dl compared with 4.8 +/- 0.5 mg/dl for controls (n=20). Similarly, TT was longer (P<0.01) in FLD, 284.5 +/- 26.1 sec/100 microl compared with 82.8 +/- 1.0 sec/100 microl for controls. Since the liver is a major site for RLP formation and degradation, it is affected to a greater extent in patients with FLD. It is likely that high levels of RLP can impair microvascular perfusion in the liver tissue and contribute to the development and progression of FLD.

2-Chloroadenosine↗

PubMed1999

Analyses of microsatellite instability and the transforming growth factor-beta receptor type II gene mutation in sporadic breast cancer and their correlation with clinicopathological features.

To determine the incidence of microsatellite instability (MSI) and its relationship with both clinicopathologic parameters and patient survival, 101 cases of breast cancer were investigated. In addition, transforming growth factor-beta (TGF-beta) receptor type II (RII) gene mutation was also examined to clarify the relation to MSI in breast cancer development. MSI and RII gene mutation were screened by single strand conformation polymorphism (SSCP). The mutations of the RII gene were confirmed by a direct sequence. An association between the MSI status and the clinicopathological features was examined to assess the potential of the MSI status as a prognostic indicator in sporadic breast cancer cases. MSI was detected in 12 of 101 (11.9%) breast cancer cases. The positive MSI breast cancer cases showed relatively more advanced disease than negative MSI cases, and also exhibited relatively poorer prognoses. No RII gene mutations were observed in any of the breast cancer cases. Our data suggest that the MSI status may thus be a useful indicator for the prognosis of sporadic breast cancer cases. However, the breast seems to be an infrequent target organ for cancer development through RII gene mutations. As a result, tumor progression through this pathway appears to be related to organ specificity. For positive MSI breast cancers, other target genes therefore still need to be identified.

Breast Neoplasms↗

PubMed1999

Successful treatment of advanced natural killer cell lymphoma with high-dose chemotherapy and syngeneic peripheral blood stem cell transplantation.

CD56+ angiocentric lymphoma has currently been recognized as a distinct clinical entity which is the prototype of the putative NK cell lymphomas. A 16-year-old Japanese girl with advanced CD56+ angiocentric lymphoma received high-dose chemotherapy supported with syngeneic peripheral blood stem cell transplantation (PBSCT). Prior to syngeneic PBSCT, she received six cycles of conventional chemotherapy before transplantation, resulting in a partial response. PBSC were mobilized with granulocyte colony-stimulating factor (G-CSF) and collected from her identical twin. High-dose cyclophosphamide, MCNU, etoposide, and carboplatin were used for pretransplant conditioning. Syngeneic PBSCT was well tolerated. She achieved complete remission and is now surviving in continuous complete remission for more than 30 months after syngeneic PBSCT. Thus, marrow-ablative chemotherapy facilitated by autologous or allogeneic PBSCT should be considered as part of the primary therapy for poor prognosis NK cell lymphomas.

Adolescent↗

PubMed1998

Phyllodes Tumor of the Breast with a Grossly Malignant Appearance: A Case Report.

A huge phyllodes tumor of the breast that appeared grossly malignant in a 43-year-old woman is described. The patient suffered from a large breast tumor thatsuddenly increased in size over 5 months to occupy the entire breast. The tumorwas hard, ulcerated and 20 cm in greatest diameter. Diagnostic imaging(US, CT and MRI)demonstrated a circumscribed mass with a large cystic cavity. She underwent total mastectomy under a diagnosis of malignant breast tumor. Grossly, the cut surface of the tumor showed a large cystic cavity surrounding a fleshy, hemorrhagic and necrotic mass with a lobulared or trabeculared appearance. Unexpectedly, benign phyllodes tumor(PT)without any stromal overgrowth was diagnosed histologically. She has been doing well since total mastectomy. In our case and in many other reported cases, PT does not show any distinctive correlation between pathologic findings and tumor behavior. Thus wide local excision is the preferred initial treatment for PT.

Journal Article↗

PubMed1998

Bone marrow necrosis in a patient with acute myeloblastic leukemia during administration of G-CSF and rapid hematologic recovery after allotransplantation of peripheral blood stem cells.

Allogeneic peripheral blood stem cell transplantation from an HLA-identical sibling was performed for a 38-year-old male with refractory acute myeloblastic leukemia. The patient was conditioned with total body irradiation (TBI) and high-dose cytosine arabinoside (Ara-C). G-CSF (300 microg/body) was started for priming of residual leukemic cells 24 hr before the beginning of TBI (day -9). However, intolerable generalized bone pain appeared shortly after the start of first dose of G-CSF, and persisted for 3 days in spite of the cessation of G-CSF. Posttransplant hematopoietic engraftment was very rapid. Bone marrow biopsy specimens on day 14 and 30 showed typical bone marrow necrosis histologically. This is the first case of bone marrow necrosis during administration of G-CSF, and our experience suggests that PBSC could repopulate hematopoiesis in spite of severe bone marrow necrosis.

Adult↗

PubMed1998

Graft rejection and recovery of host-derived hematopoiesis after allogeneic bone marrow transplantation: relation to conditioning with high dose etoposide and total body irradiation.

Engraftment failure following allogeneic bone marrow transplantation (BMT) is rare in patients with acute leukemia, after frequent conditioning with marrow-lethal chemoradiotherapy. We evaluated the efficacy of a preparatory regimen consisting of fractionated total body irradiation (TBI) (12 Gy in six fractions) and high dose etoposide (60 mg/kg) administered as an 8-h infusion for allogeneic BMT in 16 consecutive patients with acute leukemia. Although 14 patients showed complete and sustained engraftment, the remaining two patients rejected bone marrow grafts from HLA-identical sibling donors and showed subsequent recovery of host-derived hematopoiesis. Despite the limited number of patients, this observation suggests that the immunosuppressive potential of etoposide may be inferior to that of cyclophosphamide (CY) and that etoposide as an alternative to CY as an antileukemic and immunosuppressive agent in allogeneic BMT may increase the risk of graft rejection.

Acute Disease↗

PubMed1998

Time-Resolved High-Resolution Transmission Electron Microscopy Using a Piezo-Driving Specimen Holder for Atomic-Scale Mechanical Interaction.

: Time-resolved high-resolution transmission electron microscopy at a spatial resolution of 0.2 nm and a time resolution of 1/60 sec using a piezo-driving specimen holder is reported here. Various types of atomic processes in mechanical interaction, such as contact, bonding, deformation, and fracture, in nanometer-sized gold crystallites and carbon nanotubes are demonstrated.

Journal Article↗

PubMed1998

Phagocytic function of salivary PMN after smoking or secondary smoking.

Alterations in polymorphonuclear leukocyte (PMN) functions, such as phagocytosis, chemotaxis, and oxidative burst, play a pivotal role in periodontal pathogenesis. In addition, previous studies have demonstrated a strong relationship between smoking and periodontal disease. In the present study, the effect of cigarette smoking or passive smoking (secondary smoking) on the phagocytic function of salivary PMN (SPMN) was investigated. Twenty volunteers with clinically healthy gingiva (10 smokers, 10 non-smokers) participated in this study. In a small room, the smokers and passive smokers (non-smokers) were instructed to smoke and breathe, respectively, in an identical, specific way for about 4 minutes. SPMN was isolated immediately before and after smoking or passive smoking. PMN was then incubated with fluoresbrite beads for 45 minutes at 37 degrees C and the phagocytic status estimated by using a flow cytometer. Cell viability was determined by trypan blue exclusion (smokers before smoking: 88.3%: smokers after smoking: 89.6%: non-smokers before passive smoking: 89.0%; non-smokers after passive smoking: 89.4%). In both smokers and passive smokers, the proportion of phagocytic cells increased between before and after smoking (smokers before: 33.2%; after: 42.1%: passive smokers before: 36.2%: after: 44.1%). Both increases were statistically significant (P < 0.01). These results demonstrate that the phagocytic activity of SPMN intensifies after smoking and passive smoking. They also suggest that certain substances in cigarette smoke, perhaps nicotine, overstimulate the host response in the oral cavity.

Adult↗

PubMed1998

[Hypoplastic myelodysplastic syndrome progressing to acute myelocytic leukemia (M2) after treatment with G-CSF and immunosuppressants].

A 34-year-old woman was admitted to our hospital because of pancytopenia. She had been given a diagnosis of idiopathic thrombocytopenic purpura during her first pregnancy about 7 years earlier. The patient received a diagnosis of severe aplastic anemia (AA) and was treated with methylprednisolone, cyclosporin A, and granulocyte colony-stimulating factor (G-CSF), but no hematological improvement was observed. Six months later, myeloblasts appeared in the patient's peripheral blood, and she was given a diagnosis of acute myelocytic leukemia AML (FAB : M2). No chromosomal abnormalities were found. As some dyshematopoietic features had been observed in the bone marrow when the patient was first given a diagnosis of AA, it is conceivable that she already had hypoplastic myelodysplastic syndrome (MDS) then. She was treated according to the JALSG-AML92 protocol and achieved complete remission (CR). In this case, the long-term administration of G-CSF may have played an important role in the transformation of MDS into AML. It may be difficult to strictly distinguish AA from hypoplastic MDS with slight dysplastic features, as in this case, because we have no established criteria. Recently the incidence of MDS/AML in AA patients undergoing G-CSF treatment has become a concern. We should be careful about ruling out hypoplastic MDS when diagnosing a condition as AA, especially when therapy includes G-CSF. The patient is still in CR 26 months after intensive combination chemotherapy.

Adult↗

PubMed1998

Protective effect of FK409, a spontaneous nitric oxide releaser, on ischemic acute renal failure in rats.

The contribution of nitric oxide (NO) to ischemic acute renal failure (ARF) is controversial. In the present study, we investigated the effect of FK409 ((+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexanamide ), a spontaneous NO donor, on ischemic ARF in rats. Ischemic ARF was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal functional parameters such as blood urea nitrogen, plasma creatinine, creatinine clearance, urine flow, urinary osmolality and fractional excretion of sodium were measured to test the effectiveness of the drug. Renal function in untreated ARF rats markedly decreased at 24 hr after reperfusion and thereafter tended to recover gradually. Intravenous bolus injection of FK409 at a dose of 1 mg/kg before the occlusion markedly attenuated the ischemic ARF-induced decreases in renal function, to the same extent as verapamil (1 mg/kg i.v.). The protective effect of FK409, at a dose of 3 mg/kg, was much more potent than that of the lower dose. Histopathological examination of the kidney of untreated ARF rats revealed severe renal damages, such as tubular necrosis, proteinaceous casts in tubuli and medullary congestion. These renal damages were significantly attenuated by treatment with FK409, at each dose given and this attenuation exceeded that seen with verapamil treatment. FK 409 administration led to a dose-dependent increase in NO metabolites concentration in renal venous blood immediately after the reperfusion. These findings suggest that NO has a crucial role in the pathogenesis of ischemic ARF. Spontaneous NO donors may be clinically effective in cases of ischemic ARF.

Acute Kidney Injury↗

PubMed1997

G-CSF-induced mobilization of peripheral blood stem cells for allografting: comparative study of daily single versus divided dose of G-CSF.

We conducted a comparative study on a daily single versus a divided dose of G-CSF for G-CSF-induced mobilization of peripheral blood stem cells (PBSC) in eleven HLA-identical sibling donors of allogeneic PBSC transplantation (PBSCT). Six donors received double subcutaneous injections of G-CSF at a dose of 5 micrograms/kg x 2/day for 5 days (Group A), while the remaining five received single subcutaneous injection at a dose of 10 micrograms/kg/day for 5 days (Group B). The numbers of circulating CD34+ cells, myeloid progenitors (CFU-GM) and erythroid progenitors (BFU-E) reached peak values at day 5 of G-CSF administration in both groups. The mean number of CD34+ cells harvested per apheresis was 4.4 x 10(6)/kg (cells/body weight of each donor, range: 0.8-7.9 x 10(6)/kg) in Group A and 5.1 x 10(6)/kg (range: 3.0-9.0 x 10(6)/kg) in Group B. There were no significant differences between these two groups in total numbers of CFU-GM, BFU-E, or T-lymphocytes harvested. Adverse effects including mild to moderate bone pain and thrombocytopenia were transient and well tolerated. No difference was observed in the incidence of adverse effects between the two groups. These observations suggest that there is no difference in G-CSF-induced mobilization of PBSC between daily single and divided dose of G-CSF to collect a sufficient number of PBSC for engraftment after allo-PBSCT.

Adolescent↗

PubMed1997

The effects of a simplified method for cryopreservation and thawing procedures on peripheral blood stem cells.

A simplified method for cryopreservation at -80 degrees C of peripheral blood stem cells (PBSC) has been increasingly used for autologous PBSC transplantation in Japan. Although this method, using 6% hydroxyethyl starch (HES) and 5% dimethyl sulfoxide (DMSO) as a cryoprotectant without rate-controlled freezing, has several advantages over the conventional method using 10% DMSO with rate-controlled freezing, little is known about effects of long-term cryopreservation for years and thawing process on hematopoietic progenitors. We examined the recovery rates of BFU-E and CFU-GM in sample tubes cryopreserved by the simplified method under various conditions as follows: (1) long-term storage for 1-5 years; (2) DMSO exposure for 1 h after rapid thawing; and (3) thawing at a lower temperature other than 37 degrees C. In our study, we found that the recovery rates of BFU-E and CFU-GM were not affected by the length of cryopreservation period; they remained at more than 70% on average for 16-61 months. In our hands, a 1-h exposure to DMSO after rapid thawing was not toxic for hematopoietic progenitors. Furthermore, there was no significant difference in the recovery rates of BFU-E and CFU-GM between thawing at 37 degrees C and 20 degrees C. These observations indicate that PBSC cryopreserved for at least 5 years by the simplified method can be used clinically without losing hematopoietic activity, and suggest that hematopoietic activity of the thawed PBSC may be unaffected when PBSC are infused slowly within 60 min or even when PBSC are thawed gradually at room temperature.

Blood Preservation↗

PubMed1997

Common clonal origin of lymphocytes and plasma cells in splenic lymphoma with villous lymphocytes.

In two-thirds of patients with splenic lymphoma with villous lymphocytes (SLVL) a small amount of M-protein can be detected in association with the presence of plasma cells in the peripheral blood (PB) and/or bone marrow (BM). However, it is not known whether lymphoma cells and plasma cells originate from the same clone. In this report we describe a case of SLVL which was characterized by the presence of marked monoclonal gammopathy (IgG-kappa 90 g/l) and increased plasma cells in the BM. In an attempt to elucidate the origin of lymphoma cells and plasma cells, we performed morphological, cytogenetic and molecular studies on PB mononuclear cells (PBMNC) without plasma cells and BMMNC containing 10% plasma cells from this patient. Immunofluorescence showed that lymphoma cells and plasma cells were positive for cytoplasmic gamma heavy and kappa light chains. Well-developed endoplasmic reticulum was observed in the cytoplasmic organelles of PBMNC using an electron microscope. The mean IgG concentration in the 3 d supernatant cultures of PBMNC was 374 +/- 24 microg/l. More than 50% PBMNC differentiated into plasmacytoid cells in 6 d of liquid culture with IL-3 and IL-6. Analysis by two-colour FISH revealed that karyotypic abnormalities of monosomy X and trisomy 17 existed simultaneously in both lymphoma cells and plasma cells. JH gene rearranged bands from PBMNC and BMMNC by Southern blot hybridization were identical, whereas DNAs from PBMNC failed to hybridize with the Cmu probe. These observations strongly suggest that lymphoma cells and plasma cells originate from the same clone, and that plasma cells, as well as lymphoma cells, which have undergone class switch recombination, could produce IgG type M-protein in this case.

Aged↗

PubMed1996

Aspartate aminotransferase (AST) levels in human periodontium-derived cells.

The ability to objectively assess periodontal disease activity can significantly affect periodontal therapy. Aspartate aminotransferase (AST) is released extracellularly upon tissue destruction which suggests its potential as a key index in a quantitative assay for evaluating periodontal disease activity. The purpose of the present research was to assess the origin of AST in gingival crevicular fluid (GCF) in vitro. An experimental kit was used for the measurement of AST level in human gingival epithelial cells (HGEs), human gingival fibroblasts (HGFs), human periodontal ligament fibroblasts (HPLFs), polymorphonuclear leukocytes (PMNs), and plasma in peripheral blood. AST activity levels were observed in all of the periodontally derived cells, PMNs, and plasma. A significantly high level of AST activity was observed in HGEs (104.93 +/- 8.13 KU/1000 cells). The level of AST activity in HPLFs was 18.09 +/- 3.73 KU/1000 cells. AST activity in PMNs was significantly low, approximately 2% of that observed in HPLFs. These findings may suggest that AST level in GCF is correlated with the destruction of periodontal tissue.

Adult↗