Biomedical subjects

T Shibata

Publications and source records attributed to T Shibata.

At least 217 records · Page 12Linked to original sources

PubMed1999

Camelliols A-C, three novel incompletely cyclized triterpene alcohols from sasanqua oil (Camellia sasanqua)

Three novel triterpene alcohols, camelliols A (1), B (3), and C (5), possessing a mono-, bi-, and tricyclic ring system, respectively, have been isolated, along with achilleol A, a known monocyclic triterpene alcohol, from the nonsaponifiable lipids of sasanqua oil (Camellia sasanqua). The structures of these new alcohols were determined on the basis of spectroscopic methods.

Journal Article↗

PubMed1999

Inflammatory cell-mediated tumour progression and minisatellite mutation correlate with the decrease of antioxidative enzymes in murine fibrosarcoma cells.

We isolated six clones of weakly tumorigenic fibrosarcoma (QR) from the tumorigenic clone BMT-11 cl-9. The QR clones were unable to grow in normal C57BL/6 mice when injected s.c. (1x10(5) cells). However, they formed aggressive tumours upon co-implantation with a 'foreign body', i.e. a gelatin sponge, and the rate of tumour take ranged from 8% to 58% among QR clones. The enhanced tumorigenicity was due to host cell-mediated reaction to the gelatin sponge (inflammation). Immunoblot analysis and enzyme activity assay revealed a significant inverse correlation between the frequencies of tumour formation by QR clones and the levels of manganese superoxide dismutase (Mn-SOD, P<0.005) and glutathione peroxidase (GPchi, P<0.01) in the respective tumour clones. Electron spin resonance (ESR) revealed that superoxide-scavenging ability of cell lysates of the QR clone with high level of Mn-SOD was significantly higher than that with low level of the antioxidative enzyme in the presence of potassium cyanide, an inhibitor for copper-zinc superoxide dismutase (CuZn-SOD) (P<0.001). Minisatellite mutation (MSM) induced by the inflammatory cells in tumour cells were investigated by DNA fingerprint analysis after QR clones had been co-cultured with gelatin-sponge-reactive cells. The MSM rate was significantly higher in the subclones with low levels of Mn-SOD and GPchi (P<0.05) than in the subclones with high levels of both enzymes. The MSM of the subclones with low levels of both enzymes was inhibited in the presence of mannitol, a hydroxyl radical scavenger. The content of 8-hydroxydeoxyguanosine (8-OHdG) by which the cellular DNA damage caused by active oxygen species can be assessed was significantly low in the tumours arising from the QR clone with high levels of Mn-SOD and GPchi even if the clone had been co-implanted with gelatin sponge, compared with the arising tumour from the QR clone with low levels of those antioxidative enzymes (P<0.001). In contrast, CuZn-SOD and catalase levels in the six QR clones did not have any correlation with tumour progression parameters. These results suggest that tumour progression is accelerated by inflammation-induced active oxygen species particularly accompanied with declined levels of intracellular antioxidative enzymes in tumour cells.

Animals↗

PubMed1999

Depletion of Escherichia coli 4.5S RNA leads to an increase in the amount of protein elongation factor EF-G associated with ribosomes.

In Escherichia coli, 4.5S RNA is found in complexes with both protein translocation protein, Ffh (a bacterial homolog of mammalian SRP54) and protein synthesis elongation factor G (EF-G). To analyze the function of 4.5S RNA in translation, we initially assessed the sensitivity of the association of 4.5S RNA with the ribosome after treatment with antibiotics that affect various stages of protein synthesis. Fusidic acid and viomycin caused 4.5S RNA to cosediment with the 70S ribosomal fraction, indicating that 4.5S RNA enters the ribosome before ribosomal translocation and release of EF-G-GDP from the ribosome. On the other hand, depletion of 4.5S RNA led to the retention of a significant amount of EF-G on 70S ribosomes. In addition, 4.5S RNA shares a conserved decanucleotide sequence (58GAAGCAGCCA67) motif with the characterized EF-G-binding site at positions 1068-1077 on 23S RNA. We therefore examined by gel mobility-shift assay whether or not mutations in the domain-IV region of 4.5S RNA, including this conserved motif, disturb the binding of EF-G to 23S RNA. Any mutation at the C62, G64 or A67 residues within this motif abolished competition activity. Therefore, we propose that 4.5S RNA is concerned with the mode of association of EF-G with the ribosomes. Moreover, this function depends on the secondary structure of 4.5S RNA as well as a ten-base sequence conserved between the two RNAs.

Bacterial Proteins↗

PubMed1999

Subcellular localization of glucocorticoid receptor protein in the human kidney glomerulus.

BACKGROUND: The detailed mechanisms of glucocorticoid action in idiopathic nephrotic syndrome and progressive glomerulonephritides have not been clearly elucidated. The pharmacological actions of glucocorticoids are mediated by their binding to an intracellular protein, the glucocorticoid receptor (GR). The determination of GR localization in normal glomerular cells is essential to elucidate the mechanisms of glucocorticoid action in various glomerular diseases. METHODS: We carried out an immunoblot examination using antihuman GR-specific antibody and homogenates of isolated normal human glomeruli and mesangial cells in culture. Immunohistochemical examinations were also performed on normal human kidney specimens at light and electron microscopic levels. The nuclear translocation of GRs elicited by ligand binding was further investigated by confocal laser-scanning microscopic inspection of freshly isolated glomeruli and mesangial cells cultured with dexamethasone. RESULTS: An immunoblot examination demonstrated the presence of a 94 kDa protein, a molecular weight consistent with that of GRs, in the homogenates of glomeruli and cultured mesangial cells. By light microscopic examination, GRs were strongly detected in the nucleus and moderately in the cytoplasm of all glomerular cells, parietal and visceral epithelial cells, endothelial cells, and mesangial cells. By electron microscopic examination, the nuclear GRs of all glomerular cells were found to be diffusely distributed in the euchromatin. Additionally, the immunofluorescence intensities of nuclear GRs in isolated glomeruli and mesangial cells in culture became more intense by the addition of dexamethasone. CONCLUSIONS: Our findings suggest that all subsets of human glomerular cells definitely express the GR protein, which potentially undergoes translocation by glucocorticoids.

Cell Nucleus↗

PubMed1999

Role of preoperative midsagittal magnetic resonance imaging in endoscopic third ventriculostomy.

We measured the distance between the infundibular recess and the tip of the basilar artery (BA) on midsagittal magnetic resonance (MR) images in 217 subjects (mean age, 54.7 years) without intracranial disorders and 8 patients with hydrocephalus treated neuroendoscopically. The mean distance measured in the 217 subjects without intracranial disorders was 10.5 +/- 2.3 mm. There were no significant differences in this distance among age groups. In 28 of these 217 subjects (12.9%), the tip of the BA had shifted anterior to the mamillary bodies on MR images. Twenty-six of these 28 subjects (93%) were 60 years of age or older. The mean distance between the infundibular recess and the tip of the BA was 12 +/- 3.7 mm in 8 patients with hydrocephalus. There was no significant difference between the subjects without intracranial disorders and the patients with hydrocephalus in this distance. In an elderly patient with aqueductal stenosis for whom the distance between the infundibular recess and the tip of the BA was 6 mm, the tip of the BA had shifted anterior to the mamillary bodies and indented the floor of the third ventricle on preoperative midsagittal MR images, and perforation of the floor of the third ventricle therefore had to be carefully performed in order to avoid injury of the BA. Preoperative midsagittal MR images can clearly reveal neurovascular structures beneath the floor of the third ventricle and increase the safety of endoscopic third ventriculostomy.

Adolescent↗

PubMed1999

Neurosurgical simulation and navigation with three-dimensional computer graphics.

We developed a pre-operative simulation and intra-operative navigation system with three-dimensional computer graphics (3D-CG). Because the 3D-CG created by the present system enables visualization of lesions via semitransparent imaging of the scalp surface and brain, the expected operative field could be visualized on the computer display pre-operatively. We used two different configurative navigators. One is assembled by an arciform arm and a laser pointer. The arciform arm consists of 3 joints mounted with rotary encoders forming an iso-center system. The distal end of the arm has a laser pointer, which has a CCD for measurement of the distance between the outlet of the laser beam, and the position illuminated by the laser pointer. Using this navigator, surgeons could accurately estimate the trajectory to the target lesion, and the boundaries of the lesion. Because the other navigator has six degrees of freedom and an interchangeable probe shaped like a bayonet on its tip, it can be used in deep structures through narrow openings. Our system proved efficient and yielded an unobstructed view of deep structures during microscopic neurosurgical procedures.

Computer Graphics↗

PubMed1999

Inhibitory effect of glyburide on thrombin-induced platelet aggregation and phosphoinositide metabolism in normal human platelets.

We previously reported the effects of diet, sulphonylureas or insulin on thrombin-induced platelet aggregation, phosphoinositide metabolism and protein phosphorylation in non-insulin-dependent diabetes mellitus (NIDDM) patients. To clarify the mechanism of glyburide and insulin on platelet function, here we studied the in vitro effects of glyburide and insulin on thrombin-induced metabolic changes using normal human platelets. Platelet aggregation stimulated with <0.5 U/ml thrombin, 0.75-3 microM adenosine diphosphate (ADP) or 1 microg/ml collagen was significantly lower in glyburide-treated platelets, but not in insulin-treated platelets, than in untreated ones (control). Thrombin-induced incorporation of 32P radioactivity into phosphatidic acid (PA) in glyburide-treated platelets was lower than that in control but not in insulin-treated platelets. Phosphorylated proteins of platelets induced by thrombin and 12- O -tetradecanoylphorbol 13-acetate (TPA) in glyburide-treated platelets were suppressed, but not in insulin-treated platelets, compared with control. These results suggest that glyburide induces suppression of thrombin-induced activation of phospholipase C, which mediates hydrolysis of PIP and PIP(2) and production of PA, and subsequently inhibits platelet aggregation.

Journal Article↗

PubMed1999

A significant correlation between clonogenic radiosensitivity and the simultaneous assessment of micronucleus and apoptotic cell frequencies.

PURPOSE: To study the relationship between clonogenic radiosensitivity and a simultaneous assessment of the percentages of radiation-induced micronuclei (MN) and apoptotic cells. MATERIALS AND METHODS: Five mammalian cell lines were studied. Following irradiation, measurements were made of the percentages of MN, apoptotic cells and floating cells. Each factor was compared, both alone and as the simple sum of the factors, with cell survival. The factors were also evaluated using a multiple linear regression analysis. RESULTS: The simple sum of the MN and apoptotic cell percentages, the sum of the MN and floating cell percentages, and the sum of all three factors correlated with cell survival. However, the multiple linear regression analysis was the best method of predicting cell survival. CONCLUSIONS: These results suggest the usefulness of the simultaneous assessment of the MN frequency and the detection of floating cells in culture medium or apoptotic cells among attached cells to predict cellular intrinsic radiosensitivity. In order to predict cell survival after irradiation from these factors, the use of multivariate analyses is more useful than simple summation.

Animals↗

PubMed1999

Fecal steroid excretion is increased in rats by oral administration of gymnemic acids contained in Gymnema sylvestre leaves.

Gymnemic acids are the saponins with a triterpenoid structure contained in Gymnema sylvestre leaves and have the hypoglycemic effects. In spite of the cholesterol-binding properties of saponins, the effect of gymnemic acids on cholesterol metabolism has not been elucidated to date. We investigated the effects of gymnemic acids on fecal steroid excretion in rats. Three kinds of extracts from Gymnema sylvestre leaves, extract (GSE), acid precipitate (GSA) and column fractionate (GSF), of which the gymnemagenin (an aglycone of gymnemic acids) concentrations are 58.87, 161.6, and 363.3 mg/g respectively, were used for the experiments. These were administered to rats orally at the dose of 0.05-1.0 g/kg for 22 d. Rats were given free access to water and nonpurified diet without cholesterol, and the differences in fecal excretion of steroids and gymnemic acids were investigated. Although there were no significant effects of GSE, GSA and GSF decreased body weight gain and food intakes in a dose-dependent manner (P < 0.01). GSF (1.0 g/kg) significantly increased fecal excretion of neutral steroids and bile acids in a dose-dependent manner (P < 0.05), especially those of cholesterol and cholic acid (CA)-derived bile acids. The increases in fecal steroid excretion of cholesterol, total neutral steroids, total bile acids and CA-related bile acids were acute and significantly correlated with fecal gymnemagenin levels (r2 = 0.2316-0.9861, P < 0. 05). These results demonstrated for the first time that a high dose of gymnemic acids increases fecal cholesterol and CA-derived bile acid excretion. Further studies are needed to clarify the effect of gymnemic acids on cholesterol metabolism.

Administration, Oral↗

PubMed1999

Imaging the RecA-DNA complex by atomic force microscopy.

Atomic force microscopy (AFM) was applied to study the RecA protein and its complexes with DNA in air and in aqueous solution. RecA and DNA were reacted under several conditions, and deposited onto a mica substrate pre-treated in various ways. We found that the structure of the RecA and RecA-DNA complexes, especially the height of the molecules, was affected by the sample preparation method such as gel filtration, and environment during imaging.

Bacteriophage M13↗

PubMed1999

Novel DNA-binding ligands with sequence selectivity based on hydrophobic structure.

We have developed diamino-bistetrahydrofuran compounds (diamino-bisTHF) as new DNA binding molecules. Diamino-bisTHF (3:RR8) stabilized GC-rich duplex DNA with sequence specificity. DNA binding affinity increased as the alkyl chain was lengthened, indicating that the hydrophobic interaction is essential for DNA binding. It was also found that DNA binding affinity of the ligands depends on the stereochemistry of the amino group. In thermodynamic evaluation, diamino-bisTHF (3:RR8) showed a high affinity to the 12 bp duplex at a molar ratio of 1:1.

Base Sequence↗

PubMed1999

A method to detect low-level 63Ni activity for estimating fast neutron fluence from the Hiroshima atomic bomb.

The Hiroshima and Nagasaki atomic bombs resulted in the worst reported exposure of radiation to the human body. The data of survivors have provided the basis for the risk estimation for ionizing radiation, and thus are widely used as the basis of radiation safety. In this report we have studied a new method to detect the low-level 63Ni activity in copper samples in order to estimate the fast neutron fluence from the Hiroshima atomic bomb. Only 0.8 x 10(-3) Bq g(-1) of 63Ni is expected to be produced by the atomic bomb in a copper sample with the 63Cu(n, p)63Ni reaction at a distance of 500 m from the hypocenter. Our method has the required level of sensitivity for determination of the fast neutron fluence out to distances of at least 500 m, and perhaps as far as 1,000 m. We have already investigated and collected some bomb-irradiated copper samples for further study.

Beta Particles↗

PubMed1999

Posttreatment M-protein nadir level is a significant prognostic factor associated with survival in multiple myeloma. Nagoya Myeloma Cooperative Study Group.

In the present study 142 patients with myeloma (102 with IgG M-protein and 40 with IgA) treated with either VMCP (65 patients) or MMCP (77 patients) as remission induction therapy were retrospectively analyzed. Response to treatment was evaluated in terms of a more-than-50% fall of pretreatment M-protein and the posttreatment M-protein nadir. Though significantly more patients treated with MMCP achieved partial response (PR) as compared with those treated with VMCP (P=0.019) and though patients achieving PR showed a significantly longer survival than those with less responsiveness (P=0.0091), the difference in survival curves between the two treatment groups was not significant (P=0.1871). The difference in response between the treatment groups evaluated in terms of posttreatment nadir was not significant (P=0.507). Multivariate analysis identified posttreatment M-protein nadir as a significant prognostic factor associated with survival, along with 3 other factors: sex, performance status, and hemoglobin. The lack of difference between the survival curves for patients treated with the 2 regimens despite the significantly different response rates evaluated in terms of percent fall of pretreatment M-protein levels was considered to be due to the lack of a difference in the ability to induce a deep posttreatment nadir between the regimens. Posttreatment M-protein nadir is an important prognostic factor associated with survival and should be included in the evaluation of the efficacy of chemotherapy.

Aged↗

PubMed1999

Detection of hypoxic cells in murine tumors using the comet assay: comparison with a conventional radiobiological assay.

The comet (single-cell electrophoresis) assay has been developed as a method for measuring DNA damage in single cells after irradiation. We have developed our own methods and image analysis system for the comet assay to identify hypoxic fractions. In vitro, we tested our system using a cultured tumor cell line (SCCVII). In vivo, we compared the hypoxic fractions detected by this assay with those determined by the in vivo-in vitro clonogenic assay using two rodent tumors (SCCVII/ C3H, EMT6/KU/balb/c), which exhibit different types of hypoxia: acute and chronic. In vitro, our method could differentiate hypoxic cells from oxic cells, using the parameter of tail moment. In vivo, there were good correlations between the hypoxic fractions determined by the comet assay and by the clonogenic assay, in SCCVII/C3H (r=0.85) and in EMT6/KU/balb/c (r=0.75) tumors. By comparison of the two methods in chronically hypoxic and acutely hypoxic tumors, we further confirmed that the comet assay is clinically useful for estimating hypoxic fractions of solid tumors.

Animals↗

PubMed1999

Bilirubin pigmentation of human teeth caused by hyperbilirubinemia.

This study was conducted to identify bilirubin in deciduous teeth obtained from two patients with a history of severe liver dysfunction. Teeth were histologically analyzed and bilirubin was extracted and quantified spectrophotometrically. Histological analysis revealed a green line in the dentine running parallel to the incremental lines. A chloroform/methanol/acetic acid (30:10:0.5, v/v) extract of the teeth was evaporated and the residue dissolved in chloroform. Absorption spectra were prepared before and after the diazo reaction. The absorption maximum shifted from 450 nm before to 540 nm after the diazo reaction and was higher than that of normal deciduous teeth. These results indicate that the discolouration of teeth in patients with severe liver dysfunction is due to bilirubin deposition.

Bilirubin↗

PubMed1999

A case of primary antiphospholipid antibody syndrome with acute renal failure showing thrombotic microangiopathy.

An 18-year-old woman complained of fever and edema and was admitted to Showa University Hospital for treatment of thrombocytopenia and deteriorating renal function. Laboratory studies demonstrated the presence of lupus anticoagulant (LA), prolongation of prothrombin time, hemolytic anemia, a negative Coombs' test, the absence of antinuclear antibodies, and a normal fibrinogen level. Renal biopsy revealed mesangial hypercellularity, severe endocapillary cell damage, and double contour of the basement membrane walls. Immunofluorescence studies demonstrated focal, peripheral, and finely granular deposits for IgG, IgM, and IgA but were negative for fibrinogen. Electron microscopy showed glomerular capillary loops with subendothelial widening and subendothelial deposits, mesangiolysis, mesangial interposition, and marked luminal narrowing. Biopsy findings were consistent with thrombotic microangiopathy. The patient was treated with hemodialysis, methylprednisolone pulse therapy, and dipyridamole. After treatment, LA disappeared, the prothrombin time became normal, and renal function improved. The renal lesions in this patient were caused by primary antiphospholipid antibody syndrome. This case strongly suggests an important causal relationship between LA and renal lesions in thrombotic microangiopathy. We present this case to promote understanding of the pathogenesis of primary antiphospholipid antibody syndrome.

Acute Kidney Injury↗

PubMed1999

Effect of wood creosote and loperamide on propulsive motility of mouse colon and small intestine.

To elucidate a mechanism of the antidiarrheal activity of wood creosote, its effect on the propulsive motility of mouse colon and small intestine was studied using a charcoal meal test and a colonic bead expulsion test. The effect was compared with that of loperamide. At an ordinary therapeutic dose, wood creosote inhibited the propulsive motility of colon, but not of small intestine. On the other hand, loperamide inhibited the propulsive motility of small intestine, but not of colon. The results indicate that at least a part of the antidiarrheal activity of wood creosote and loperamide is attributable to their antikinetic effect predominantly on colon of the former and predominantly on small intestine of the latter.

Animals↗

PubMed1999

A new family of growth factors produced by the fat body and active on Drosophila imaginal disc cells.

By fractionating conditioned medium (CM) from Drosophila imaginal disc cell cultures, we have identified a family of Imaginal Disc Growth Factors (IDGFs), which are the first polypeptide growth factors to be reported from invertebrates. The active fraction from CM, as well as recombinant IDGFs, cooperate with insulin to stimulate the proliferation, polarization and motility of imaginal disc cells. The IDGF family in Drosophila includes at least five members, three of which are encoded by three genes in a tight cluster. The proteins are structurally related to chitinases, but they show an amino acid substitution that is known to abrogate catalytic activity. It therefore seems likely that they have evolved from chitinases but acquired a new growth-promoting function. The IDGF genes are expressed most strongly in the embryonic yolk cells and in the fat body of the embryo and larva. The predicted molecular structure, expression patterns, and mitogenic activity of these proteins suggest that they are secreted and transported to target tissues via the hemolymph. However, the genes are also expressed in embryonic epithelia in association with invagination movements, so the proteins may have local as well as systemic functions. Similar proteins are found in mammals and may constitute a novel class of growth factors.

Amino Acid Sequence↗