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Biomedical subjects

D Mizuno

Publications and source records attributed to D Mizuno.

At least 19 recordsLinked to original sources
PubMed2001

Electrophoretic microrheology in a dilute lamellar phase of a nonionic surfactant.

We measured the complex electrophoretic mobility mu(*)(omega) of nanometer-sized particles dispersed in a lyotropic lamellar phase, and observed two relaxation processes corresponding to the two characteristic lengths of lamellar structure. Faster relaxation is caused by the distortion field of lamellar phase induced by the colloidal particles, and slower relaxation is presumably due to the defects in lamellar structure. Since the dynamic transport property is strongly influenced by the microscopic circumstances as shown in this paper, this method is referred to as electrophoretic microrheology.

Journal Article↗
PubMed2001

Measurement of liquid surface properties by laser-induced surface deformation spectroscopy.

We developed a technique of picking up the liquid surface in a noncontact manner by a cw-laser radiation. The momentum change of light at the laser transmission through the air-liquid interface appears as the radiation pressure, which deforms the liquid surface into the shape determined by the balance between the Laplace force of the curved surface and the radiation pressure. The displacement of the liquid surface is inversely proportional to the surface tension, which was measured by an optical probe. The dynamic response of the liquid surface deformation was theoretically derived under the periodical modulation of the radiation pressure. The experimentally observed spectra were in good agreement with the theory giving the dynamic properties of the liquid surface. The technique of the laser induced surface deformation has potential as a measurement tool of the surface dynamic properties, such as the time-dependent surface tension and surface viscoelasticity.

Journal Article↗
PubMed2000

Chlorzoxazone: a probe drug whose metabolism can be used to monitor toluene exposure in rats.

In this study we investigated cytochrome P450 (CYP) 2E1 expression using a probe drug, chlorzoxazone (CZX), whose metabolism can be used to monitor toluene exposure in rats. The animals received an i.p. injection of toluene (0.25, 0.5 and 1 ml/kg) once a day for 3 days. The total CYP and CYP2E1 content and the aniline and CZX hydroxylase activity (Vmax and CL(int)) increased depending on the dose of toluene administered. At the highest concentration (128 mM) of diethyldithiocarbamate, a specific inhibitor of CYP2E1, the production of 6-hydroxychlorzoxazone (HCZX) in microsomes from toluene-treated rats was reduced by about 80%. The IC50 values in microsomes from toluene-treated rats were between 3 and 5 microM. The production of HCZX and the activity of aniline hydroxylase in toluene-treated rats were correlated with the amount of rat CYP2E1 protein (r = 0.88 and r = 0.88, respectively). The elimination of CZX by toluene-treated rats was increased and the HCXZ production in the toluene-treated group was greater than that in the olive oil control group. The correlations between intrinsic clearance (CL(int): Vmax/Km) in vitro and total body clearance (CL(tot)) of CZX hydroxylation and the elimination half-life (t1/2) of CZX in vivo in toluene-treated rats were high (r = 0.784, P < 0.001; r = -0.678, P < 0.001, respectively). In addition, the metabolic plasma HCZX/CZX ratio did not require multiple blood sampling and 2 h after CZX administration in vivo there was also a high correlation with CL(int) (Vmax/Km) in vitro (r = -0.729, P < 0.001). In conclusion, these results demonstrate that CZX is a very good probe for monitoring induction in toluene-treated rats.

Animals↗
PubMed1999

Age- and sex-related changes in toluene metabolism by rat hepatic microsomes in vitro.

Age- and sex-related changes in toluene metabolism by hepatic microsomes of male and female Sprague-Dawley (SD) rats (1 to 20 weeks) were investigated. A major metabolite of toluene, benzyl alcohol (BA), was measured by high-performance liquid chromatography (HPLC). At low substrate toluene concentrations (0.4 mM), in male rats, BA increased dramatically with development, reaching a peak at 5 weeks of age, rapidly decreasing thereafter. In female rats, BA increased dramatically with development at 3 to 5 weeks of age, and then declined gradually to a low level. Gender differences were obtained at 5 and 20 weeks of age, with BA products being higher in males than in females. At high substrate toluene concentrations (5.0 mM), in male rats, the BA formation pattern was similar to that at the low substrate concentration, although the rate of increase with age was slower. In female rats, a peak was obtained at 3 weeks of age, and then declined gradually to a low level. Gender differences were obtained at 5, 15 and 20 weeks of age, with BA products being higher in males than in females. These results indicate that toluene metabolism exhibits age and gender differences.

Aging↗
PubMed1998

Involvement of 26-kDa membrane-bound tumour necrosis factor precursor in bidirectional feedback regulation on 17-kDa tumour necrosis factor production after stimulation by lipopolysaccharide.

The authors have previously shown that 26-kDa membrane-bound tumour necrosis factor precursor (proTNF) on the cell-surface of primed human monocytic cell line THP-1 is involved in positive feedback regulation of lipopolysaccharide (LPS)-dependent TNF-production. Here, we provide direct evidence for modulation of responsiveness of the THP-1 cells against LPS by membrane-bound pro-TNF. When THP-1 cells were cocultivated with a heterogeneous cell line (proTNF/3T3 cells) which constitutively expressed membrane-bound proTNF, LPS-dependent TNF-production by THP-1 cells was significantly suppressed and the normal level was restored by the presence of anti-TNF antibody during cocultivation. The proTNF-3T3-induced decline of TNF-production of THP-1 was observed primarily at the mRNA level, although no difference was observed in the mRNA level of interleukin 1 beta, another LPS-inducible cytokine. These results suggest that proTNF could also be involved in the negative feedback regulation of LPS-dependent TNF-production through cell-to-cell contact. The augmentation of LPS-dependent TNF-production accompanied by the production of endogenous proTNF induced by exogenous agent was inhibited by protein kinase C inhibitor, whereas proTNF/3T3-induced suppression of TNF-production could not be restored to the normal level. It thus seems possible that proTNF might act on macrophages as a bidirectional regulator of its production by THP-1 cells depending on co-induced signals.

3T3 Cells↗
PubMed1997

Structural characterization of lipid A obtained from Pantoea agglomerans lipopolysaccharide.

Lipopolysaccharide isolated from Pantoea agglomerans showed higher priming and triggering activities for macrophages in terms of tumor necrosis factor production than other lipopolysaccharides. To identify the difference in biological activities of lipopolysaccharide of Pantoea agglomerans from other lipopolysaccharides on the basis of structure, we determined the structure of the lipid A part, which is the biological center of lipopolysaccharides, by quantitative analysis, nuclear magnetic resonance spectroscopy and mass spectrometry. Lipopolysaccharide of Pantoea agglomerans is constructed with at least two kinds of lipid A of different levels of acylation. One is of the same type as that of Escherichia coli with hexa-acyl lipid A and the other is the Salmonella minnesota type with hepta-acyl lipid A.

Bacterial Proteins↗
PubMed1995

Molecular cloning of a cDNA that encodes the precursor to several exogastrula-inducing peptides, epidermal-growth-factor-related polypeptides of the sea urchin Anthocidaris crassispina.

Complementary DNA clones for exogastrula-inducing peptides (EGIPs) of the sea urchin Anthocidaris crassispina, which are related to epidermal growth factor (EGF), were obtained from a cDNA library of late gastrula embryos using, as probe, the partial cDNA for one of the EGIP (EGIP-D) obtained by the reverse-transcription PCR method. The longest cDNA was composed of 1662 bp, and encoded a protein of approximately 36 kDa with a region that resembled a signal sequence. The deduced protein contains the sequences of EGIP-C, EGIP-D, and EGIP-A in that order, followed by the sequence for an unidentified EGIP-like polypeptide. When expressed in Escherichia coli as a fusion protein with beta-galactosidase, the product for the cDNA was specifically recognized by a rabbit antibody raised against EGIP-D that had been purified from embryos. Characteristic amino acid residues were found around the N-terminus and the C-terminus of each EGIP sequence, suggesting a specific processing mechanism for the generation of the individual EGIPs from the precursor. RNA-blot analysis revealed the presence of EGIP mRNA in unfertilized eggs. The level of this mRNA decreased gradually after fertilization, began to increase dramatically after the onset of gastrulation, and continued to increase through the pluteus stage. Genomic Southern-blot analysis suggested that this gene is present as a single copy. A homology search showed that the EGIP cDNA has a similarity to the cDNA for SpEGF2 which was cloned as a gastrula-specific gene in another sea urchin, Strongylocentrotus purpuratus.

Amino Acid Sequence↗
PubMed1994

Antinociceptive effect of lipopolysaccharide from Pantoea agglomerans on streptozotocin-induced diabetic mice.

The antinociceptive effect of lipopolysaccharide from Pantoea agglomerans (LPSp) in streptozotocin-induced diabetic mice was examined. Although subcutaneous (s.c.) administration of LPSp produced a dose-dependent inhibition of the tail-flick response in both non-diabetic and diabetic mice, the antinociceptive response was greater in diabetic mice than in non-diabetic mice. The antinociceptive effects of LPSp in both diabetic and non-diabetic mice were significantly antagonized by s.c. administration of naltrindole, a selective delta-opioid receptor antagonist or nor-binaltorphimine, a selective kappa-opioid receptor antagonist, but not by beta-funaltrexamine, a selective mu-opioid receptor antagonist. These results suggest that LPSp produces a marked antinociceptive effect in diabetic mice through the activation of delta- and kappa-opioid receptors.

Analgesics↗
PubMed1994

Constitutive expression of TNF-alpha and -beta genes in mouse embryo: roles of cytokines as regulator and effector on development.

1. Using the RT/PCR method, we examined mRNA expression of several inflammatory factors in mouse embryos during mid-late embryonal development. mRNAs of tumor necrosis factor (TNF)-alpha, TNF-beta, their receptors (TNF-RI, TNF-RII), transforming growth factor (TGF)-beta, were expressed constitutively in most of the embryonic tissues. 2. While mRNAs of other factors, interleukin (IL)-1 alpha, IL-1 beta, IL-3, IL-6, granurocyte-colony stimulating factor (G-CSF), leukaemia inhibitory factor (LIF), and interferon (IFN)-gamma were only limitedly expressed. 3. The mRNAs of several complement components (C2, C3, C4, C5) and receptors (CR1, CR2) were also detected. Among them, the expression of C3 and CR1 were prominent. These results strongly support our idea that inflammation-like system play an important role to regulate embryogenesis.

Animals↗
PubMed1994

Effects of a lipopolysaccharide from Pantoea agglomerans on the cocaine-induced place preference.

A lipopolysaccharide from Pantoea agglomerans (LPSp) was purified, and its effect on the cocaine-induced place preference was examined in rats. Cocaine (4 mg/kg, i.p.) produced a significant place preference. Administration of LPSp (5-1000 micrograms/kg, i.p.) alone resulted in neither preference nor aversion for either the drug- or saline-associated place. However, pretreatment with LPSp (500 and 1000 micrograms/kg, i.p.) abolished the place preference that had been induced by cocaine. Furthermore, treatment with LPSp (500 micrograms/kg, i.p.) abolished cocaine (20 mg/kg, i.p.)-induced locomotor enhancement in mice. These results suggest that while LPSp itself may possess neither reinforcing nor locomotor enhancing effects, it blocks both the reinforcing and the locomotor enhancing effects of cocaine. Therefore, LPSp might be useful in pharmacotherapy for prevention of recurrent cocaine abuse.

Animals↗
PubMed1994

Enhanced production of tumour necrosis factor alpha (TNF-alpha) by its precursor on the cell surface of primed THP-1 cells.

To clarify the biological significance of tumour necrosis factor alpha (TNF-alpha) precursor, we analysed its expression at the primed and triggered stages using human monocyte-like cell line THP-1. To prime them, THP-1 cells were treated with either recombinant human interferon gamma (rIFN-gamma) or recombinant human tumour necrosis factor alpha (rTNF-alpha). At the primed stage, transient accumulation of TNF-alpha, mRNA and a small amount of 26-KDa TNF-alpha precursor was observed, and the precursor molecule was located on the cell surface. Following treatment of the primed cells with bacterial lipopolysaccharide (LPS), augmentation of transcription of TNF-alpha mRNA and production of a larger amount of TNF-alpha precursor were observed followed by secretion of a larger amount of mature TNF-alpha (17-KDa) than secreted by the unprimed cells (triggered stage). This suggests that with priming THP-1 cells might be changed to a stage where they are ready for production of a larger amount of TNF-alpha at the triggered stage. When either primed or unprimed THP-1 cells were pretreated with anti-TNF-alpha antibody, augmentation of TNF-alpha production by primed THP-1 cells was specifically suppressed, suggesting that TNF-alpha precursor itself may play an important role in the enhancement of TNF-alpha production by the primed macrophages after treatment with LPS.

Cell Line↗
PubMed1994

Suppression of hyperalgesia in streptozotocin-induced diabetic mice by a lipopolysaccharide from Pantoea agglomerans.

The ability of a lipopolysaccharide from Pantoea agglomerans (LPSp) to relieve hyperalgesia was examined by observing its inhibition of the decrease in the threshold for nociceptive perception, as determined by the tail-pinch test, in streptozotocin-induced diabetic mice. Subcutaneous injection of LPSp suppressed hyperalgesia in streptozotocin-induced diabetic mice and also exerted a therapeutic effect on hyperalgesia in these animals. The present data suggest that LPSp may be effective in relieving the pain associated with diabetic neuropathy.

Animals↗
PubMed1994

Heterogeneity in lysosomal fusion with phagocytic vesicles and cell membrane in non-phagocytosing guinea-pig polymorphonuclear leukocyte.

The fusion of lysosomes and other granules with phagocytic vesicles (endo-fusion) and cell membrane (exocytosis) was simultaneously examined in non-phagocytosing guinea-pig polymorphonuclear leukocytes (PMNs). beta-Glucuronidase as a typical lysosomal enzyme, acid phosphatase as another lysosomal enzyme, and alkaline phosphatase as a specific granule enzyme were assayed. PMNs released these three enzymes in the presence of serum but the extents of exocytosis differed considerably: release of beta-glucuronidase, alkaline phosphatase and acid phosphatase was 6.9, 4.3 and 3.3%, respectively. Acid phosphatase was released even in the absence of serum, whereas the other two enzymes were not. These three enzymes showed also different responses in endofusion: the preformed phagocytic vesicles fused with the granules containing beta-glucuronidase and acid phosphatase, but scarcely fused with those containing alkaline phosphatase, although all these enzymes were recovered in increasing amounts in the phagolysosome fraction when the cells were allowed to phagocytose continuously. These results suggest that fusion of these three types of granules with phagocytic vesicles (endo-fusion) and plasma membrane (exocytosis) is heterogeneous and regulated by different mechanisms in guinea-pig PMNs.

Animals↗
PubMed1993

Gangliosides can activate human alternative complement pathway.

The alternative complement pathway (ACP) in vertebrates is known to be important in inflammatory reactions, and to be activated by foreign substances such as bacterial lipopolysaccharide (LPS) and zymosan, although to date no intrinsic activators have been identified except complement receptor type 2. From the point of the structural similarity of LPS to ganglioside, we have investigated gangliosides which are abundantly present in animal cells for their activity on the human ACP. All of seven gangliosides tested were found to activate this pathway in a manner depending on the number of sialic acids and neutral sugars contained in the molecules. A dose-response study suggested a correlation of the threshold in ganglioside concentration with its critical micelle concentration. Gangliosides may thus serve as an intrinsic activator for ACP in animals, thereby leading to inflammation. The possibility of the participation of sialidase in complement activation is also discussed.

Complement Pathway, Alternative↗
PubMed1992

Expression of transcripts of complement components and their receptors during differentiation of embryonal carcinoma cell lines.

Based on our previous finding that TNF-alpha and TNF-beta can be expressed constitutively during early embryonal development [1], we extended our work to identify factors which are generally known to take part in inducing inflammation in adults. They can be regarded as candidate molecules involved in ontogenic inflammation during embryonal development. In this study, we chose the factors which are constituents of either a classical or an alternative pathway of a complement system and found that mRNAs corresponding to those of C2, C3, C4, C5 and to those of receptors CR1 and CR2 were expressed. Among them, mRNA expression of C3, C4, and CR1 was especially constitutive. Contrary to these observations, expression of two kinds of scavenger receptors (SR-I, SR-II) proved to be negative. In this report, the framework of ontogenic inflammation as a regulatory mechanism in embryonal development at the molecular level is discussed.

Animals↗
PubMed1992

BRM activities of low-toxic Bordetella pertussis lipopolysaccharides.

A low-toxic lipopolysaccharide (BP-LPS) was isolated from killed Bordetella pertussis (Tohama strain). LD50 of BP-LPS was about 0.8 mg/mouse which was about 10-fold higher than the LD50 of E. coli-LPS(80 micrograms/mouse). Toxicity measured by decrease in body weight of BP-LPS-injected mice was similarly low. BP-LPS had strong antitumor activities against various murine syngeneic tumors, and its systemic administration caused clear regression of such as MM46 mammary carcinoma and Meth A fibrosarcoma. It is noteworthy that a tolerable dosage of BP-LPS (375 micrograms/mouse) showed clear antitumor activity against MH134 hepatoma, which is known to be insusceptible to usual types of BRM including bacterial LPS. These findings suggest that BP-LPS is a promising candidate as an antitumor agent for clinical use. Biological activities of BP-LPS were examined and compared with those of toxic LPS extracted from Escherichia coli and other enterobacteria. Activation or stimulation of macrophages and lymphocytes by these LPS, including TNF induction, was found to be similar. However, activation of human or murine neutrophils, as estimated by neutrophil-adherence assay in vitro, though induced by all other toxic LPS tested, was not induced by BP-LPS. This inability of BP-LPS to activate neutrophils is assumed to be related to its low toxicity.

Animals↗
PubMed1992

Homeostasis as regulated by activated macrophage. IV. Analgesic effect of LPSw, a lipopolysaccharide of wheat flour.

The effect of LPSw, a lipopolysaccharide from a water extract of wheat flour, on pain response was investigated using an acetic acid-induced writhing test in mice. LPSw inhibited writhing dose-dependently in the range of 10 ng-10 micrograms/mouse i.v. This effect reached its maximum 1.5-3 h after the LPSw inoculation and was detectable even after 8 h. The analgesic effect of LPSw was inhibited by i.v. injection of naloxone and also beta-endorphin was detected in serum and brain tissue following injection of LPSw. Preliminary clinical trials were done in which LPSw was administered percutaneously to relieve the pain of patients with herpes. The results showed that pain was relieved by this application. LPSw may be the best analgesic drug so far known, since it induces the endogenous mediator of analgesia, beta-endorphin.

Analgesics↗