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Biomedical subjects

Y Miyazaki

Publications and source records attributed to Y Miyazaki.

At least 55 records · Page 3Linked to original sources
PubMed2003

Tumor necrosis factor alpha and insulin resistance in obese type 2 diabetic patients.

The relationship between basal serum tumor necrosis factor alpha (TNFalpha) levels and peripheral tissue (muscle) sensitivity to insulin was examined in 63 subjects with normal glucose tolerance (NGT), 18 subjects with impaired glucose tolerance (IGT), and 123 patients with type 2 diabetes mellitus (T2DM). The BMI was similar in NGT (28.8+/-0.7 kg/m(2)), IGT (31.1+/-1.0), and T2DM (30.0+/-0.4) groups. The fasting serum TNFalpha concentration in T2DM (4.4+/-0.2 pg/ml) was significantly higher than in NGT (3.1+/-0.2) and IGT (3.4+/-0.2; both P<0.05). In T2DM the fasting plasma glucose (FPG=183+/-5 mg/dl) and insulin (FPI=17+/-1 micro U/ml) concentrations were significantly higher than in NGT (FPG=95+/-1; FPI=10+/-1) and IGT (FPG=100+/-2; FPI=13+/-1; all P<0.01). The rate of total body insulin-mediated glucose disposal (Rd; 40 mU/m(2) min euglycemic insulin clamp in combination with (3)H-glucose) was reduced in T2DM (102+/-3 mg/m(2) min) compared with NGT (177+/-10) and IGT (151+/-14; both P<0.01). The serum TNFalpha concentration was inversely correlated with Rd (r=-0.47, P<0.0001) and positively correlated with both FPG (r=0.32, P=0.004) and FPI (r=0.32, P=0.004) in NGT plus IGT. No correlation was observed between serum TNFalpha and Rd (r=-0.02), FPG (r=0.15), or FPI (r=0.15) in T2DM. In stepwise multiple regression analysis using age, sex, BMI, FPG, FPI and serum TNFalpha concentration as independent variables, only BMI and serum TNFalpha concentration were significant and independent predictors of Rd (r(2)=0.29, P<0.0001) in the NGT plus IGT group, while FPG and FPI were significant and independent predictors of Rd (r(2)=0.13, P<0.0001) in T2DM. These results suggest that: (i) an increase in circulating TNFalpha concentration is associated with peripheral insulin resistance and increased plasma glucose and insulin levels prior to the onset of type 2 diabetes; and (ii) the further deterioration in peripheral insulin resistance in T2DM (compared with NGT and IGT) is unrelated to the increase in serum TNFalpha concentration.

Adult↗
PubMed2003

The percentage of myeloperoxidase-positive blast cells is a strong independent prognostic factor in acute myeloid leukemia, even in the patients with normal karyotype.

To examine whether the percentage of myeloperoxidase (MPO)-positive blast cells is useful as a prognostic factor for acute myeloid leukemia (AML), cytochemical analysis of MPO was performed in 491 patients who were registered to the Japan Adult Leukemia Study Group-AML92 study. Patients were divided into two using the percentage of MPO-positive blast (high [>or=50%] and low (<50%)). Complete remission rates were 85.4% in the former and 64.1% in the latter (P=0.001). The overall survival (OS) and the disease-free survival (DFS) were significantly better in the high MPO group (48.3 vs 18.7% for OS, and 36.3 vs 20.1% for DFS, P<0.001, respectively). Multivariate analysis showed that both karyotype and the percentage of MPO-positive blast cells were equally important prognostic factors. The high MPO group still showed a better survival even when restricted to the intermediate chromosomal risk group or the patients with normal karyotype (P<0.001). The OS of patients with normal karyotype in the high MPO group was almost equal with that of the favorable chromosomal risk group. The percentage of MPO-positive blast cells is a simple and highly significant prognostic factor for AML patients, and especially useful to stratify patients with normal karyotype.

Acute Disease↗
PubMed2003

Th2 cytokines, IgE and mast cells play a crucial role in the induction of para-phenylenediamine-induced contact hypersensitivity in mice.

We previously reported the establishment of a mouse model system of contact hypersensitivity (CHS) to paraphenylemediamine (PPD). In order to analyse the functional contribution of Th2 cytokines, IL-4 and IL-5, in PPD induced CHS, STAT6 deficient (STAT6-/-) and wild-type control (WT) mice (C57BL/6) were immunized by the topical application of a PPD solution, and then the subsequent skin reactions were examined. Ear swelling was significantly reduced with a delayed peak response in STAT6-/- mice as compared with that of WT mice. A histological analysis showed the infiltration of both eosinophils and neutrophils in the skin of STAT6-/- mice challenged 24 h previously to significantly decrease in comparison with that in the WT mice. The expression of Th2 cytokines (IL-4, IL-5) by ELISA in the PPD-challenged skin tissue specimens as well as the IgE and IgG1 response after challenge were also profoundly reduced in the STAT6-/- mice. The adoptive transfer of the serum obtained from sensitized WT mice for the putative IgE transfer induced a peak response at 3 h and 24 h after challenge. To further investigate the role of mast cells in the induction of PPD-CHS, mast cell deficient W/Wv mice were sensitized with PPD and then were challenged. Maximal ear swelling was detected from 12 to 24 h and another small peak response was observed at 1 h in+/+mice, whereas only a small peak response at 24 h was detected in W/Wv mice. These data indicate that not only Th2 cytokines and IgE but also mast cells play an essential role in the induction of PPD-CHS.

Adoptive Transfer↗
PubMed2003

Detection of Legionella DNA by PCR of whole-blood samples in a mouse model.

A detection system for Legionella DNA in blood samples based on the PCR was developed and evaluated in A/J mice with experimentally induced Legionella pneumonia. Primers were designed to amplify a 106 bp DNA fragment of the 16S rRNA gene specific to Legionella species. The PCR system could detect clinically relevant Legionella species including Legionella pneumophila, Legionella micdadei, Legionella bozemanae, Legionella dumoffii, Legionella longbeachae, Legionella gormanii and Legionella jordanis. The sensitivity of the PCR system was 20 fg extracted DNA. In the mouse model, the blood PCR was compared with results obtained by PCR on bronchoalveolar lavage fluid (BALF) samples, cultures of blood and BALF and detection of Legionella urinary antigen. Blood PCR was positive until 8 days after infection, while BALF PCR became negative on day 4. These results indicate that PCR using blood samples may be a useful, convenient and non-invasive method for the diagnosis of Legionella pneumonia.

Animals↗
PubMed2003

Gastrin activates nuclear factor kappaB (NFkappaB) through a protein kinase C dependent pathway involving NFkappaB inducing kinase, inhibitor kappaB (IkappaB) kinase, and tumour necrosis factor receptor associated factor 6 (TRAF6) in MKN-28 cells transfected with gastrin receptor.

BACKGROUND: We previously reported that gastrin induces expression of CXC chemokines through activation of nuclear factor kappaB (NFkappaB) in gastric epithelial cells that express gastrin receptor. AIMS: To clarify gastrin receptor mediated signals leading to activation of NFkappaB. METHODS: MKGR26 cells were created by transfecting gastrin receptor cDNA into MKN-28 cells. Degradation of inhibitor kappaB (IkappaB) and phosphorylation of protein kinase C (PKC)-delta were both detected by western blot analysis. NFkappaB activation was determined by luciferase assay and electrophoretic mobility shift analysis. RESULTS: Gastrin induced degradation of IkappaB-alpha and activation of NFkappaB, which was abolished by the selective gastrin receptor antagonist L-740,093 and the general PKC inhibitor GF109203X. Gastrin induced phosphorylation of PKC-delta, and its inhibitor rottlerin partially suppressed NFkappaB activation. However, the mitogen activated protein kinase (MAPK) kinase inhibitor PD98059, p38 MAPK inhibitor SB203580, and tyrphostin AG1478 had no effect on NFkappaB activation. Introduction of the dominant negative mutant of IkappaB kinase, of NFkappaB inducing kinase, and of tumour necrosis factor receptor associated factor 6 (TRAF6), but not that of TRAF2, inhibited gastrin induced activation of NFkappaB. CONCLUSIONS: Gastrin activates NFkappaB via a PKC dependent pathway which involves IkappaB kinase, NFkappaB inducing kinase, and TRAF6.

Animals↗
PubMed2002

Enhanced macrophage responsiveness to lipopolysaccharide and CD40 stimulation in a murine model of inflammatory bowel disease: IL-10-deficient mice.

OBJECTIVE: To elucidate the role of macrophages in the pathogenesis of inflammatory bowel disease, proinflammatory characteristics of macrophages were estimated in a murine model of spontaneous intestinal inflammation. MATERIALS AND METHODS: Peritoneal macrophages from IL-10deficient mice were stimulated with lipopolysaccharide (LPS) or an anti-CD40 monoclonal antibody (mAb). Cytokine release was assessed by enzyme-linked immunosorbent assay. CD40 expression was examined by two-color flow cytometric analysis. Induction of suppressor of cytokine signaling 3 (SOCS3) mRNA was evaluated by real-time quantitative RT-PCR. RESULTS: In the presence of LPS or anti-CD40 mAb, TNF-alpha and IL-12p70 release from macrophages of mutant mice was significantly higher than that from macrophages of wild-type mice. This may be due to the difference in IL-10 production by macrophages, since activated macrophages of wild-type mice produced IL-10 in amounts sufficient to suppress an increased release of cytokines from activated macrophages of mutant mice. LPS and CD40 stimulation induced significantly high level of SOCS3 expression in macrophages of mutant mice in comparison to those of wild-type mice. CONCLUSIONS: Macrophages from a murine model of inflammatory bowel disease demonstrated enhanced responsiveness to immunological and bacterial stimuli. This suggests significant roles of macrophages in the pathogenesis of inflammatory bowel disease.

Animals↗
PubMed2002

Clinical and neuroradiological improvement in chronic acquired hepatocerebral degeneration after branched-chain amino acid therapy.

We report two patients with chronic acquired hepatocerebral degeneration (CAHD) who showed neurological and radiological improvement after the administration of branched-chain amino acids (BAA). The first patient with chronic hepatitis C presented with progressive parkinsonism for 7 months, whereas the second patient with liver cirrhosis presented with progressive ataxia for 15 months. T1-weighted magnetic resonance imaging (MRI) showed symmetric high intensity signals in the lenticular nuclei in both patients. In the first patient, single photon emission computed tomography (SPECT) disclosed a marked decrease in cerebral blood flow in the parieto-occipital regions. In the second patient, T2-weighted MRI demonstrated symmetric high intensity signals in the deep cerebral and cerebellar white matter. After the administration of BAA, their neurological signs and radiological abnormalities markedly improved in both patients. CAHD might be a reversible and treatable disorder where aromatic amino acids are deeply involved in its pathogenesis.

Aged↗
PubMed2002

Effects of xenon on acetylcholine release in the rat cerebral cortex in vivo.

BACKGROUND: We have reported previously the effects of several anaesthetics on cholinergic activity in the central nervous system (CNS). In this study, we report the effects of xenon on cholinergic cell activity. METHODS: Using in vivo brain microdialysis, we measured acetylcholine (ACh) release in the rat cerebral cortex in vivo during xenon anaesthesia. RESULTS: Xenon induced an initial increase in ACh release, followed by a gradual decrease. The level of Ach release at 40 min of xenon administration was significantly higher than the control. CONCLUSIONS: Xenon activates CNS cholinergic cell activity followed by development of acute tolerance.

Acetylcholine↗
PubMed2002

A new method for measuring dynamic change of tracer distribution using dynamic single photon emission tomography with a slip-ring rotational gamma camera.

The clinical applicability of dynamic single photon emission tomograpy (SPET) using a dual-head gamma camera equipped with a slip-ring rotational mechanism, referred to as serial SPET, was examined in the present investigation. Serial SPET enables the production of tomographic images for any arbitrary time frame from an arbitrary range of data to 360 degrees. In a pre-clinical evaluation, a correlation between radioactivity concentration and serial SPET counts was evaluated in a phantom with continuous changes in 99mTc concentration. A differential value was obtained from each pair of SPET images; moreover, moving average approximation processing was investigated with respect to the elimination of noise in the data. In 11 and one patient presenting with cerebrovascular disease and meningioma, respectively, changes in SPET counts were evaluated when 99mTc ethyl cysteinate dimer (99mTc-ECD) was continuously administered at a constant rate in the resting state. Furthermore, in six of 11 subjects with cerebrovascular disease, changes occurring in SPET counts were examined by using acetazolamide loading while continuously administering 99mTc-ECD at a constant rate. Consequently, serial SPET enabled the evaluation of changes in radioactivity concentration over time in both the phantom and preliminary clinical studies. Data analysis by differential processing utilizing moving average approximation processing enabled the detection of minor changes in radioactivity concentration. An increase of 15.1+/-5.4% was observed in SPET counts of the unaffected cerebral hemisphere with acetazolamide loading. The response of the affected hemisphere was less prominent. These findings suggest that serial SPET would be an effective technique for the pharmacokinetic analysis of radiopharmaceuticals.

Acetazolamide↗
PubMed2002

Epidemiological investigation of a fatal case of cholera in Japan by phenotypic techniques and pulsed-field gel electrophoresis.

A fatal case of cholera caused by Vibrio cholerae 01 El Tor serotype Ogawa occurred in Aichi Prefecture, Japan in 1995. The patient was identified locally, but the route of the infection was unknown. The causative isolate and 38 other domestic and imported V. cholerae O1 isolates, obtained between 1984 and 1997, were analysed by prophage typing, antimicrobial susceptibility testing and pulsed-field gel electrophoresis (PFGE). This was done to determine whether the isolate from this case differed from others associated with either mild cholera infections or asymptomatic carriage, and to elucidate the route of infection. Cholera toxin (CT) from 37 toxigenic isolates was assayed semi-quantitatively. The 39 isolates were divided into 12 temporary types in accordance with the results of the three typing techniques. The isolate from the fatal infection and nine other isolates were classified as temporary type IV. No difference in CT production was found between the isolate from the fatal case and the other 36 toxigenic isolates. Taken together, it is unlikely that a V. cholerae 01 isolate of distinguishable type was responsible for the fatal illness. Temporary type IV isolates were frequently present in both domestic and imported cases from 1994 to 1997 in Aichi, but they did not emerge before 1993. These results suggest that a new clone was introduced after 1993 from overseas and then disseminated into Aichi, and this may have been an important step in triggering the fatal case of cholera.

Adult↗
PubMed2001

Magnetic-field-dependent heat capacity of the single-molecule magnet [Mn(12)O(12)(O(2)CEt)(16)(H(2)O)(3)].

Accurate heat capacities of the single-molecule magnet [Mn(12)O(12)(O(2)CEt)(16)(H(2)O)(3)] were measured from 0.3 to 311 K by adiabatic calorimetry without an external magnetic field. Heat-capacity anomalies were separated by assuming several contributions including lattice vibration, magnetic anisotropy, and hyperfine splitting. Among them, a tiny thermal anomaly between 1 and 2 K is attributable to the presence of Jahn-Teller isomers. The heat capacities of the polycrystalline sample were also measured with applied magnetic fields from 0 to 9 T in the 2-20 K temperature region by the relaxation method. With an applied magnetic field of up to 2 T, a steplike heat-capacity anomaly was observed around the blocking temperature T(B) approximately 3.5 K. The magnitude of the anomaly reached a maximum at 0.7 T. With a further increase in the magnetic field, the step was decreasing, and finally it disappeared above 3 T. The step at T(B) under 0.7 T can be roughly accounted for by assuming that a conversion between the up-spin and down-spin states is allowed above T(B) by phonon-assisted quantum tunneling, while it is less effective below T(B). Excess heat capacity under a magnetic field revealed a large heat-capacity hump around 14 K and 2 T, which would be attributed to a thermal excitation from the S = 9 ground state to the spin manifold with different S values, where S is the total spin quantum number.

Journal Article↗
PubMed2001

PPARgamma agonists inhibit cell growth and suppress the expression of cyclin D1 and EGF-like growth factors in ras-transformed rat intestinal epithelial cells.

Peroxisome proliferator-activated receptor gamma (PPARgamma) inhibits the growth of several types of cancer cells. However, the mechanisms by which this occurs are poorly understood. The goal of the present study was to investigate the effects of PPARgamma on mutated ras-induced cell growth, activation of transcription factors and expression of genes associated with cellular transformation in rat intestinal epithelial cells. A human PPARgamma cDNA was introduced to the activated H-ras-transfected IEC-6 cells (IECras) and 1 clone (IECrasPR82) that stably expresses both activated ras and PPARgamma was obtained. Thiazolidinedione derivatives such as troglitazone and rosiglitazone, selective ligands for PPARgamma, inhibited the cellular growth of IECrasPR82 cells in a time-dependent manner and induced G1 cell cycle arrest. Treatment with troglitazone (20 microM) decreased the expression of cyclin D1, heparin-binding epidermal growth factor-like growth factor (HB-EGF) and amphiregulin and suppressed the promoter activities of cyclin D1 and HB-EGF. Furthermore, a luciferase assay and an electrophoretic mobility shift assay showed that thiazolidinedione derivatives suppressed the transcriptional activities of AP-1 and Ets, both of which play crucial roles in the expression of cyclin D1 and HB-EGF. These findings suggest that reduction of EGF-like growth factors and cyclin D1 through the suppression of AP-1 and Ets may be 1 mechanism whereby PPARgamma inhibits their growth.

Animals↗
PubMed2001

A 30-base-pair element in the first intron of SOX9 acts as an enhancer in ATDC5.

SOX9 is a transcription factor that is essential for chondrogenesis and testis differentiation, and haploinsufficiency of SOX9 causes campomelic dysplasia, severe skeletal malformation syndrome with variably penetrant XY sex reversal. Here we demonstrate that in several cell lines that express SOX9, 30-bp element in the first intron of human SOX9 gene act as a potential enhancer in the ATDC5 chondroprogenitor cell line, despite the apparent absence of cell-specific regulatory elements within a 5.5-kb promoter region. Deletion and site-specific mutational analyses reveal that the last 12 bp of the 30-bp element are critical for transcriptional activity, while 5'-half sequences are necessary for full transactivation. Gel retardation assays indicate the possible involvement of several binding factors along the length of this element. These results suggest that functionally interdependent elements in the 30-bp enhancer region of the first intron account for basal expression levels of Sox9 in ATDC5.

3T3 Cells↗
PubMed2001

Involvement of heparin-binding EGF-like growth factor and its processing by metalloproteinases in early epithelial morphogenesis of the submandibular gland.

In the present study, the role of a member of the epidermal growth factor (EGF) family, heparin-binding EGF-like growth factor (HB-EGF), in organ development was investigated by using developing mouse submandibular gland (SMG), in which the EGF receptor signaling and heparan sulfate chains have been implicated. HB-EGF mRNA was detected in developing SMG by RT-PCR analysis and was expressed mainly in epithelium and weakly in mesenchyme of the embryonic SMG. Epithelial morphogenesis was inhibited by a synthetic peptide corresponding to the heparin-binding domain of HB-EGF and by anti-HB-EGF neutralizing antibody. An in vitro assay using an EGF receptor ligand-dependent cell line, EP170.7 cells, allowed us to detect the growth factor activity in SMG-conditioned media, which was significantly reduced by anti-HB-EGF antibody. Furthermore, treatment of SMG rudiments with the hydroxamate-based metalloproteinase inhibitor OSU8-1, which inhibits processing of EGFR ligands including HB-EGF, markedly diminished the growth factor activity in conditioned media and resulted in almost complete inhibition of SMG morphogenesis. The inhibitory effects on morphogenesis were reversed, though partially, by adding the soluble form of HB-EGF. Our results provide the first evidence that HB-EGF is a crucial regulator of epithelial morphogenesis during organ development, highlighting the importance of its processing by metalloproteinases.

Amino Acid Sequence↗
PubMed2001

Cyclin A-dependent phosphorylation of the ETS-related protein, MEF, restricts its activity to the G1 phase of the cell cycle.

MEF, a recently identified member of the E74 family of ETS-related transcription factors, is a strong transcriptional activator of cytokine gene expression. Using a green fluorescent protein gene reporter plasmid regulated by an MEF-responsive promoter, we determined that the transcriptional activity of MEF is largely restricted to the G1 phase of the cell cycle. MEF-dependent transcription was suppressed by the expression of cyclin A but not by cyclin D or cyclin E. This effect was due to the kinase activity generated by cyclin A expression, as co-expression of the cyclin-dependent kinase inhibitors p21 or p27, or a dominant negative form of CDK2 (DNK2), abrogated the reduction of MEF transcriptional activity by cyclin A. Cyclin A-CDK2 phosphorylated MEF protein in vitro more efficiently than cyclin D-CDK4 or cyclin E-CDK2, and phosphorylation of MEF by cyclin A-CDK2 reduced its ability to bind DNA. We determined one site of phosphorylation by cyclin A-CDK2 at the C terminus of MEF, using mass-spectrometry; mutation of three serine or threonine residues in this region significantly reduced phosphorylation of MEF by cyclin A and reduced cyclin A-mediated suppression of its transactivating activity. These amino acid substitutions also reduced the restriction of MEF activity to G1. Phosphorylation of MEF by the cyclin A-CDK2 complex controls its transcriptional activity during the cell cycle, establishing a novel link between the ETS family of proteins and the cell cycle machinery.

Amino Acid Sequence↗
PubMed2001

Application of ion-exchange cartridge clean-up in food analysis IV. Confirmatory assay of benzylpenicillin, phenoxymethylpenicillin, oxacillin, cloxacillin, nafcillin and dicloxacillin, in bovine tissues by liquid chromatography-electrospray ionization tandem mass spectrometry.

A multiresidue analytical method was developed for the confirmation of benzylpenicillin (PCG), phenoxymethylpenicillin (PCV), oxacillin (MPIPC), cloxacillin (MCIPC), nafcillin (NFPC) and dicloxacillin (MDIPC) in bovine tissues using electrospray ionization liquid chromatography-tandem mass spectrometry (LC-ESI-MS-MS) with a product ion scan mode. All penicillins gave [M-H]-, [M-H-CO2]- and [M-H-141]- as the product ion, when [M-H]- was selected as the precursor ion. Combination of an ion-exchange cartridge clean-up and the LC-ESI-MS-MS method can reliably identify all of these penicillins fortified at a concentration of 0.05 mg/kg in bovine tissues, including liver, kidney and muscle. The limits of confirmation satisfy the maximum residue limits for each of the penicillins established by the World Health Organization, US Food and Drug Administration, European Union and Japan.

Animals↗