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Biomedical subjects

H Mizuno

Publications and source records attributed to H Mizuno.

At least 37 records · Page 2Linked to original sources
PubMed2001

Interleukin-1beta induces the expression of lipocortin 1 mRNA in cultured rat cortical astrocytes.

Lipocortin 1 (LC1) has been shown to increase in neuronal damage and act as a neuroprotectant and a neurotrophic factor. IL-1beta acts as a mediator of inflammation and has been reported as a potent inducer of various neurotrophic factors including nerve growth factor and fibroblast growth factor. In this study, we investigated the relationship between LC1 and IL-1beta in cultured rat astrocytes. Time-and dose-dependent experiments of IL-1beta on rat cortical astrocytes in culture revealed that the expression of LC1 mRNA was significantly augmented by IL-1beta at 8 h, 10 ng/ml. In addition, IL-1beta evoked an extracellular secretion of LC1 without its cytotoxic effects. The effect of IL-1beta was completely abolished when we treated cells with inhibitor of mitogen-activated protein kinases (MAPKs) (PD98059) (25 microM), phospholipase A(2) inhibitor mepacrine (30 microM) and protein synthesis inhibitor cycloheximide (CHX) (10 microg/ml). This suggests that induction of LC1 by IL-1beta is through a MAPKs and phospholipaseA(2) pathway and requires protein synthesis. These results indicate that IL-1beta released in the central nervous system (CNS) injury can stimulate the transcription of the LC1 gene. Subsequent synthesis and release of LC1 may provide trophic support to neurons and modulate the action of IL-1beta in brain damage.

Animals↗
PubMed2001

Removal of mixtures of acetaldehyde and propionaldehyde from waste gas in packed column with immobilized activated sludge gel beads.

The removal of mixed acetaldehyde and propionaldehyde as a model of the binary contaminants in waste gas was studied in the packed column containing the immobilized activated sludge gel beads together with the hollow plastic balls developed for the removal of a single aldehyde in the previous work. The rate of each aldehyde biodegradation by the gel beads in the aldehydes mixture was expressed by the Michaelis-Menten type rate equation with an inhibitory term due to the other coexistent aldehyde. The kinetic parameters involved were found to be the same as those determined previously for biodegradation of a single aldehyde. A model for prediction of removal of each aldehyde in the packed column was developed assuming that each aldehyde dissolved in the aqueous phase within the gel bead was biodegraded according to the above rate equation with no mass transfer effect. The packed column was stable and efficient for removal of the binary aldehydes mixture with a very low pressure drop for gas flow due to a reduced gel beads bed compaction by the hollow plastic balls. Removal of each aldehyde decreased with increasing the inlet aldehyde concentrations since each biodegradation rate itself approached asymptotically the maximum one with increase in each aldehyde concentration. The observed removals for each aldehyde in the aldehydes mixture agreed well with those calculated from the design equations developed. The contact efficiency of gel beads with the waste gas stream was estimated to be the same value of 0.24 as in the previous work, supporting that the efficiency was specific to the geometrical and physical properties of the packed column used.

Journal Article↗
PubMed2001

FRET-based in vivo Ca2+ imaging by a new calmodulin-GFP fusion molecule.

Intracellular Ca2+ acts as a second messenger that regulates numerous physiological cellular phenomena including development, differentiation and apoptosis. Cameleons, a class of fluorescent indicators for Ca2+ based on green fluorescent proteins (GFPs) and calmodulin (CaM), have proven to be a useful tool in measuring free Ca2+ concentrations in living cells. Traditional cameleons, however, have a small dynamic range of fluorescence resonance energy transfer (FRET), making subtle changes in Ca2+ concentrations difficult to detect and study in some cells and organelles. Using the NMR structure of CaM bound to the CaM binding peptide derived from CaM-dependent kinase kinase (CKKp), we have rationally designed a new cameleon that displays a two-fold increase in the FRET dynamic range within the physiologically significant range of cytoplasmic Ca2+ concentration of 0.05-1 microM.

Animals↗
PubMed2001

The ERK MAP kinase pathway mediates induction of SGK (serum- and glucocorticoid-inducible kinase) by growth factors.

BACKGROUND: The ERK MAP kinase pathway plays a pivotal role in growth factor-induced gene expression. However, genes whose expression is induced by the ERK pathway are not fully defined. RESULTS: We have identified SGK (serum- and glucocorticoid-inducible kinase) as an ERK-inducible gene by the subtractive screening of Raf-inducible genes. SGK is known to be similar in primary structure to AKT/PKB, PKC and PKA. Treatment of quiescent NIH-3T3 cells with FGF, PDGF or TPA, which induced the sustained activation of ERKs, resulted in the strong induction of SGK, whereas treatment with EGF, which induced the transient activation of ERKs, did not induce a strong expression of SGK. The induction of SGK was blocked by pre-treatment with a specific MEK inhibitor U0126, and expression of constitutively active MEK was able to induce SGK. Treatment with cycloheximide or vanadate prolonged the increased expression of SGK by FGF, concomitant with a more prolonged activation of ERKs. CONCLUSION: Growth factor-induced activation of the ERK MAP kinase pathway is necessary and sufficient for the induction of SGK.

3T3 Cells↗
PubMed2001

Participation of ATP in cell volume regulation in the endothelium after hypotonic stress.

1. The role of ATP in the regulatory volume decrease (RVD) after hypotonic cell swelling was examined in cultured endothelial cells isolated from the rat caudal artery. 2. Hypotonic stress increased [Ca2+]i in addition to increasing the overflow of ATP and cell volume. The hypotonicity induced increase in [Ca2+]i was prevented by pyridoxalphosphate-6-azophenyl-1-2',4'-disulphonic acid (PPADS; a P2 purinoceptor antagonist), U-73122 (a phospholipase C inhibitor) and thapsigargin (a Ca2+ pump inhibitor). However, the hypotonicity induced increase in cell volume was potentiated by PPADS, U-73122 and thapsigargin. 3. Similar changes were observed in cells treated with 2-methylthioATP, a P2Y purinoceptor agonist, but not by alpha,beta-methylene ATP, a P2X purinoceptor agonist. Thus, it appears that the responses observed following hypotonic stress are mediated by activation of P2Y purinoceptors. 4. On the basis of these findings, it is suggested that ATP, which is released by hypotonicity, may participate in the RVD as a substantial regulator or initiator via P2 purinoceptor-induced increases in [Ca2+]i.

Adenosine Triphosphate↗
PubMed2001

The antioxidant effect of DL-alpha-lipoic acid on copper-induced acute hepatitis in Long-Evans Cinnamon (LEC) rats.

The Long-Evans Cinnamon (LEC) rats, due to a genetic defect, accumulate excess copper (Cu) in the liver in a manner similar to patients with Wilson's disease and spontaneously develop acute hepatitis with severe jaundice. In this study we examined the protective effect of DL-alpha-Lipoic acid (LA) against acute hepatitis in LEC rats. LA was administered to LEC rats by gavage in doses of 10, 30 and 100 mg/kg five times per week, starting at 8-weeks-old and continuing till 12-weeks-old. Although LA had little effect against the increases in serum transaminase activities, it suppressed the loss of body weight and prevented severe jaundice in a dose-dependent manner. Antioxidant system analyses in liver showed that LA treatment significantly suppressed the inactivations of catalase and glutathione peroxidase, and the induction of heme oxygenase-1, an enzyme which is inducible under oxidative stress. Furthermore, LA showed dose-dependent suppressive effect against increase in nonheme iron contents of both cytosolic and crude mitochondrial fractions in a dose-dependent manner. Although at the highest dose, LA slightly suppressed the accumulation of Cu in crude mitochondrial fraction, it had no effect on the accumulation of Cu in cytosolic fraction. While LA completely suppressed the increase in lipid peroxidation (LPO) in the microsomal fraction at the highest dose, the suppressive effect against LPO in crude mitochondrial fractions was slight. From these results, it is concluded that LA has antioxidant effects at the molecular level against the development of Cu-induced hepatitis in LEC rats. Moreover, mitochondrial oxidative damage might be involved in the development of acute hepatitis in LEC rats.

Acute Disease↗
PubMed2001

Multilineage cells from human adipose tissue: implications for cell-based therapies.

Future cell-based therapies such as tissue engineering will benefit from a source of autologous pluripotent stem cells. For mesodermal tissue engineering, one such source of cells is the bone marrow stroma. The bone marrow compartment contains several cell populations, including mesenchymal stem cells (MSCs) that are capable of differentiating into adipogenic, osteogenic, chondrogenic, and myogenic cells. However, autologous bone marrow procurement has potential limitations. An alternate source of autologous adult stem cells that is obtainable in large quantities, under local anesthesia, with minimal discomfort would be advantageous. In this study, we determined if a population of stem cells could be isolated from human adipose tissue. Human adipose tissue, obtained by suction-assisted lipectomy (i.e., liposuction), was processed to obtain a fibroblast-like population of cells or a processed lipoaspirate (PLA). These PLA cells can be maintained in vitro for extended periods with stable population doubling and low levels of senescence. Immunofluorescence and flow cytometry show that the majority of PLA cells are of mesodermal or mesenchymal origin with low levels of contaminating pericytes, endothelial cells, and smooth muscle cells. Finally, PLA cells differentiate in vitro into adipogenic, chondrogenic, myogenic, and osteogenic cells in the presence of lineage-specific induction factors. In conclusion, the data support the hypothesis that a human lipoaspirate contains multipotent cells and may represent an alternative stem cell source to bone marrow-derived MSCs.

Adipocytes↗
PubMed2001

ORI-GENE: gene classification based on the evolutionary tree.

MOTIVATION: Genome projects have produced large amounts of data on the sequences of new genes whose functions are as yet unknown. The functions of new genes are usually inferred by comparing their sequences with those of known genes, but evaluation of the sequence homology of individual genes does not make the most of the available sequence information. Therefore, new methods and tools for extracting more biological information from homology searches would be advantageous. RESULTS: We have developed a computational tool, ORI-GENE, to analyze the results of sequence homology searches from the perspective of the evolution of selected sets of new genes. ORI-GENE has a graphical interface and accomplishes two important tasks: first, based on the output of homology searches, it identifies species with similar genes and displays their pattern of distribution on the phylogenetic tree. This function enables one to infer the way in which a given gene may have propagated among species over time. Second, from the distribution patterns, it predicts the point at which a given gene may have been first acquired (i.e. its 'origin'), then classifies the gene on that basis. Because it makes use of available evolutionary information to show the way in which genes cluster among species, ORI-GENE should be an effective tool for the screening and classification of new genes revealed by genome analysis. AVAILABILITY: ORI-GENE is retrievable via the Internet at: http://www.rtc.riken.go.jp/jouhou/ORI-GENE.

Animals↗
PubMed2001

Crystal structure of Bacillus stearothermophilus alpha-amylase: possible factors determining the thermostability.

The crystal structure of a thermostable alpha-amylase from Bacillus stearothermophilus (BSTA) has been determined at 2.0 A resolution. The main-chain fold is almost identical to that of the known crystal structure of Bacillus licheniformis alpha-amylase (BLA). BLA is known to be more stable than BSTA. A structural comparison between the crystal structures of BSTA and BLA showed significant differences that may account for the difference in their thermostabilities, as follows. (i) The two-residue insertion in BSTA, Ile181-Gly182, pushes away the spatially contacting region including Asp207, which corresponds to Ca(2+)-coordinating Asp204 in BLA. As a result, Asp207 cannot coordinate the Ca(2+). (ii) BSTA contains nine fewer hydrogen bonds than BLA, which costs about 12 kcal/mol. This tendency is prominent in the (beta/alpha)(8)-barrel, where 10 fewer hydrogen bonds were observed in BSTA. BLA forms a denser hydrogen bond network in the inter-helical region, which may stabilize alpha-helices in the barrel. (iii) A few small voids observed in the alpha-helical region of the (beta/alpha)(8)-barrel in BSTA decrease inter-helical compactness and hydrophobic interactions. (iv) The solvent-accessible surface area of charged residues in BLA is about two times larger than that in BSTA.

Amino Acid Sequence↗
PubMed2001

Effect of fudosteine, a new cysteine derivative, on mucociliary transport.

We examined the effect of fudosteine ((-)-(R)-2-amino-3-(3-hydroxypropylthio)propionic acid) on the mucociliary transport (MCT) rate in quails. The MCT rate was estimated by ash transport velocity on the tracheal mucosa of quails. Fudosteine (500 mg kg(-1), p.o.) did not affect the normal MCT rate. However, topical application of fudosteine to the tracheal mucosa dose-dependently protected the impairment of the MCT rate caused by exposure to cigarette smoke. The results suggest that fudosteine may participate in the defence mechanism in the respiratory tract against irritant gases.

Administration, Oral↗
PubMed2001

Enhanced signal transduction by a directly fused protein of interleukin-6 and its receptor.

In order to develop a new type of agonist for the interleukin 6 (IL-6) signal, the gene encoding a directly fused protein (DFP) was constructed by joining the N-terminal portion of IL-6 and the C-terminal (soluble) portion of IL-6R (sIL-6R) without using a flexible polypeptide linker. The biological activity if DFP from a recombinant Pichia pastoris was examined by growth stimulation of IL-6-dependent BAF130 cells expressing human gp130, a membrane receptor. The recombinant DFP exhibited a much stronger growth stimulation (10 times) than the independent IL-6 and sIL-6R (IL-6/sIL-6R), mainly because association of the IL-6 and IL-6R could be maintained even at lower concentrations of DFP. Surface plasmon resonance (SPR) analysis showed that DFP bound to the extracellular portion of gp130 in the biphasic mode, and the dissociation constants of DFP for two phases were the same as those of IL-6/sIL-6R. In cells treated with DFP, stimulation of Stat3 phosphorylation was maintained for a longer period (150 min) than in cells treated with IL6/Il-6R, suggesting that the signal mediated by the DFP was more durable than that mediated by IL-6/sIL-6R, although the signal transduction mechanisms are almost the same for both DFP and IL-6/IL-6R. Therefore, the stronger activity of DFP was attributed to the maintained association of its subunits and/or prolonged phosphorylation of Stat3.

Journal Article↗
PubMed2001

Restitutive response of Mini rat liver to injury induced by a single oral administration of thioacetamide.

Mini rats are a transgenic rat strain carrying antisense gene for rat growth hormone (GH), resulting in retarded growth and a lower blood GH level (136 +/- 42.0 ng/mL) compared with that of age-matched parental strain Wistar rats (329 +/- 337 ng/mL). Mini rats have been used by several investigators as a GH deficiency model. In this work, we gave a single oral administration of thioacetamide (TAA), a hepatotoxicant, to both Mini rats and Wistar rats to ascertain the influence of GH deficiency on liver response to chemically induced injury and subsequent regeneration. TAA administration caused liver injury in both strains, with a greater extent of injury in Mini rats. Proliferation of bile epithelial cells and so-called oval cells was prominent at Day 3 in Mini rats only, and this change correlated well with serum total bilirubin concentrations. Antibody against Ki-67 antigen revealed that cellular proliferation after TAA-induced liver injury was suppressed but prolonged in the Mini rat liver. Although hepatic stellate cells and Kupffer cells/macrophages were more abundant in the livers of TAA-treated Mini rats, the hepatic expression patterns of hepatocyte growth factor and transforming growth factor beta 1 were comparable to those of Wistar rats. Insulin-like growth factor-I gene expression was significantly reduced in the Mini rat liver. Our results imply that a lower GH level may exacerbate chemically induced liver injury, enhance infiltration/proliferation of non-parenchymal cells, suppress regeneration of hepatocytes, and induce proliferation of bile epithelial cells and oval cells when the liver is injured by TAA.

Administration, Oral↗
PubMed2001

[Biochemical markers in clinical trials for NDA of anti-osteoporotic drugs].

Alendronate expecting new drug registration soon is the first anti-osteoporotic drug fully utilizing biochemical markers in clinical trials for NDA. In clinical trials of anti-osteoporotic drugs being on the market in Japan only classical biochemical markers were measured. The effects to new biochemical markers should be checked in post-marketing studies. So far bone resorption markers have been extensively studied because present anti-osteoporotic drugs are anti-bone-resorption type. From now progress of bone formation markers is expected along with studies of bone forming type anti-osteoporotic drugs.

English Abstract↗
PubMed2000

Generation, characterization, and kinetics of triplet Di[1,2,3,4,5,6, 7,8-octahydro-1,4:5,8-di(ethano)anthryl]carbene.

The title carbene has been generated by photolysis of the corresponding diazo precursors and studied by spectroscopic means, i. e., electron paramagnetic resonance (EPR) and UV/vis spectroscopy in matrixes at low temperature and laser-flash photolysis in solution at room temperature, with the product analysis. The results are compared with triplet di(2,3,5,6-tetramethylphenyl)carbene, an open-chain counterpart, which revealed that bicycloalkyl groups are acting as a fairly good kinetic protector for the triplet carbene as opposed to the open-chain counterpart. The formation of all-hydrocarbon triplet carbenes having a half-life over a second under normal conditions was realized for the first time. Effects of para-substituents on the structure and reactivities of the carbene are also investigated and discussed in terms of polar and spin electronic effects.

Journal Article↗
PubMed2000

Therapeutic effect of 1 M tegafur-0.4 M 5-chloro-2, 4-dihydroxypridine-1 M potassium oxonate (S-1) on head and neck squamous carcinoma cells.

1 M Tegafur (FT)-0.4 M 5-chloro-2,4-dihydroxypridine (CHDP)-1 M potassium oxonate (Oxo) (S-1), was developed as a new oral antineoplastic agent based on biochemical modulation of fluorouracil (5-FU) by CHDP and Oxo. The antitumor effect of S-1 on human head and neck squamous carcinoma cells was evaluated in xenografts and a metastasis model, in comparison with combined drug of 1 M FT and 4 M uracil (UFT). Mice treatment with S-1 showed a significant higher concentration of 5-FU in the tumor and the serum than UFT treated mice. S-1 showed higher tumor growth inhibition and metastasis inhibition than UFT. The mice in which metastasis was inhibited lived more than twice as long as the control mice. These results suggest that S-1 will have a higher clinical therapeutic effect against advanced squamous cell carcinoma of the head and neck in humans.

Administration, Oral↗
PubMed2000

Novel sugar-binding specificity of the type XIII xylan-binding domain of a family F/10 xylanase from Streptomyces olivaceoviridis E-86.

The type XIII xylan-binding domain (XBD) of a family F/10 xylanase (FXYN) from Streptomyces olivaceoviridis E-86 was found to be structurally similar to the ricin B chain which recognizes the non-reducing end of galactose and specifically binds to galactose containing sugars. The crystal structure of XBD [Fujimoto, Z. et al. (2000) J. Mol. Biol. 300, 575-585] indicated that the whole structure of XBD is very similar to the ricin B chain and the amino acids which form the galactose-binding sites are highly conserved between the XBD and the ricin B chain. However, our investigation of the binding abilities of wt FXYN and its truncated mutants towards xylan demonstrated that the XBD bound xylose-based polysaccharides. Moreover, it was found that the sugar-binding unit of the XBD was a trimer, which was demonstrated in a releasing assay using sugar ranging in size from xylose to xyloheptaose. These results indicated that the binding specificity of the XBD was different from those of the same family lectins such as the ricin B chain. Somewhat surprisingly, it was found that lactose could release the XBD from insoluble xylan to a level half of that observed for xylobiose, indicating that the XBD also possessed the same galactose recognition site as the ricin B chain. It appears that the sugar-binding pocket of the XBD has evolved from the ancient ricin super family lectins to bind additional sugar targets, resulting in the differences observed in the sugar-binding specificities between the lectin group (containing the ricin B chain) and the enzyme group.

Binding Sites↗
PubMed2000

Crystal structure of Streptomyces olivaceoviridis E-86 beta-xylanase containing xylan-binding domain.

Xylanases hydrolyse the beta-1,4-glycosidic bonds within the xylan backbone and belong to either family 10 or 11 of the glycoside hydrolases, on the basis of the amino acid sequence similarities of their catalytic domains. Generally, xylanases have a core catalytic domain, an N and/or C-terminal substrate-binding domain and a linker region. Until now, X-ray structural analyses of family 10 xylanases have been reported only for their catalytic domains and do not contain substrate-binding domains. We have determined the crystal structure of a family 10 xylanase containing the xylan-binding domain (XBD) from Streptomyces olivaceoviridis E-86 at 1.9 A resolution. The catalytic domain comprises a (beta/alpha)(8)-barrel topologically identical to other family 10 xylanases. XBD has three similar subdomains, as suggested from a triple-repeat sequence, which are assembled against one another around a pseudo-3-fold axis, forming a galactose-binding lectin fold similar to ricin B-chain. The Gly/Pro-rich linker region connecting the catalytic domain and XBD is not visible in the electron density map, probably because of its flexibility. The interface of the two domains in the crystal is hydrophilic, where five direct hydrogen bonds and water-mediated hydrogen bonds exist. The sugar-binding residues seen in ricin/lactose complex are spatially conserved among the three subdomains in XBD, suggesting that all of the subdomains in XBD have the capacity to bind sugars. The flexible linker region enables the two domains to move independently and may provide a triple chance of substrate capturing and catalysis. The structure reported here represents an example where the metabolic enzyme uses a ricin-type lectin motif for capturing the insoluble substrate and promoting catalysis.

Amino Acid Motifs↗