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Biomedical subjects

H Miyazaki

Publications and source records attributed to H Miyazaki.

At least 91 records · Page 5Linked to original sources
PubMed2001

[Placement of stent for internal carotid artery stenosis in the cervical portion improved ocular ischemic syndrome].

We report a case of ocular ischemic syndrome due to severe stenosis of the internal carotid artery. The patient was a 67-year-old man with a hemispheric transient ischemic attack and an amaurosis fugax. Ocular examination showed multiple soft exudates and dilatation of the retinal veins. Carotid stenting was performed to reconstruct the internal carotid artery. The multiple soft exudates were almost diminished and the visual acuity was improved. These results suggest that carotid stenting for severe stenosis of the internal carotid artery should be one of the less invasive methods to improve the microcirculation of the retina.

Aged↗
PubMed2001

[Cerebral arteritis and cerebritis caused by subdural empyema: two cases report].

We report two cases of cerebral angitis and cerebritis caused by subdural empyema. A 22-year-old man, who complained of a headache and high fever, suddenly developed unconsciousness and right hemiparesis. CT and MRI demonstrated left subdural empyema with diffuse brain swelling. CT angiography showed diffuse narrowing of the left internal carotid artery, middle cerebral artery, and anterior cerebral artery. Although we performed craniotomy, continuous irrigation with drainage, systemic injection of antibiotics for subdural empyema, antiplatelet therapy, and hyperbaric oxygen therapy for angitis, his condition remained unchanged. A 67-year-old man who had previously undergone burr hole surgery presented to our hospital for the treatment of scalp infection. He suddenly developed unconsciousness and right hemiparesis. CT and MRI demonstrated left subdural empyema with diffuse brain swelling, but MR angiography did not show any abnormal findings. Hemiparesis improved after the surgery and systemic injection of the antibiotics. Subdural empyema with sinusitis or meningitis around the skull base sometimes causes cerebral angitis. We considered that the angiographical evaluation for the subdural empyema was necessary to detect angitis.

Adult↗
PubMed2001

Effects of cyclic strain on the morphology and phagocytosis of macrophages.

Morphology and phagocytosis of macrophages were studied after cultured under cyclic strain. Peritoneal macrophages obtained from 6-week old female C57BL/6J mice were attached to silicone rubber sheets, preincubated for 2 hours, and then cultured for 24 and 48 hours under cyclic strain of 5% amplitude and 1 Hz frequency (strained group) or no strain (non-strained group). Control data were obtained from 0-hour cultured cells (control group). Cell morphology was observed with optical and scanning electron microscopes, and shape index (SI) of each cell was determined from the perimeter and adhesion area. Phagocytotic activity was evaluated from the uptake of latex particles 1.5 microm in diameter. The morphology and phagocytosis of macrophages were affected by cyclic strain, although the percentage of differentiated cells was not the case. SI in the strained group was smaller than that in the non-strained group, and had a tendency of decreasing with time. Cyclic strain suppressed the phagocytosis of macrophages for latex particles, and there was a significant difference in the phagocytosis between the strained and the non-strained groups after 24-hour culture.

Analysis of Variance↗
PubMed2000

Changes in expressions of proinflammatory cytokines IL-1beta, TNF-alpha and IL-6 in the brain of senescence accelerated mouse (SAM) P8.

The senescence-accelerated mouse (SAM) is known to be a murine model for accelerated aging. The SAMP8 strain shows age-related deterioration of learning and memory at an earlier age than control mice (SAMR1). In the present study, we investigated the changes in expressions of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in the brain of SAMP8. In the hippocampus of 10 months old SAMP8, the expression of IL-1 mRNA was significantly elevated in comparison with that of SAMR1. In both strains of SAMs, increases in IL-1beta protein in the brain were observed at 10 months of age compared with 2 and 5 months. The only differences found between the strain in protein levels were at 10 months and were elevations in IL-1beta in the hippocampus and hypothalamus, and in TNF-alpha and IL-6 in the cerebral cortex and the hippocampus in SAMP8 as compared with SAMR1. However, lipopolysaccharide-induced increases in the expression of these cytokines in brain did not differ between SAMP8 and SAMR1. Increases in expression of proinflammatory cytokines in the brain may be involved in the age-related neural dysfunction and/or learning deficiency in SAMP8.

Aging↗
PubMed2000

Functional analysis of the C-terminal region of recombinant human thrombopoietin. C-terminal region of thrombopoietin is a "shuttle" peptide to help secretion.

Thrombopoietin (TPO) is a cytokine that primarily stimulates megakaryocytopoiesis and thrombopoiesis. TPO has a unique C-terminal tail peptide of about 160 amino acids that consists mostly of hydrophilic residues and contains six N-linked sugar chains. In order to investigate the biological function of the C-terminal domain, two series of mutations were performed. One is systematic truncation from the C terminus. Another is elimination of N-glycosylation sites in the C-terminal domain by Asn to Gln mutations. After the mutant proteins were expressed by mammalian cells, it was found that the elimination of the N-linked sugar sites did not affect the biological activity, whereas truncation of the C-terminal domain resulted in elevation of in vitro activity up to 4-fold. The C-terminal peptide itself was found to inhibit the in vitro activity. Moreover, both the C-terminal truncation and the elimination of the N-glycosylation sites decreased the secretion level progressively down to (1)/(10) that of wild type, and the amount of the mutant left in the cell increased. The N-glycosylation in the C-terminal region was found to be important for secretion of TPO. Among six N-glycosylation sites in the C-terminal region, two locations, Asn-213 and Asn-234, were found to be critical for secretion, and two other locations, Asn-319 and Asn-327, did not affect the secretion.

Animals↗
PubMed2000

Hemodialysis impairs endothelial function via oxidative stress: effects of vitamin E-coated dialyzer.

BACKGROUND: Patients who undergo hemodialysis experience accelerated atherosclerosis and premature death. Recent evidence suggests that endothelial dysfunction proceeds to and exacerbates atherosclerosis. It remains unknown whether hemodialysis per se causes endothelial dysfunction. METHODS AND RESULTS: We evaluated endothelial function estimated by flow-mediated vasodilation during reactive hyperemia using high-resolution ultrasound Doppler echocardiography before and after a single session in patients on maintenance hemodialysis. Several studies have shown that the imbalance between pro-oxidant and antioxidant activities in hemodialyzed patients results in high oxidative stress, which causes lipid peroxidation and endothelial injury. Accordingly, we investigated the effects of antioxidative modification during hemodialysis on endothelial function using a vitamin E-coated cellulose membrane dialyzer. Nonspecific endothelium-independent vasodilation was measured after administration of a sublingual glyceryl trinitrate spray (0.3 mg). A single session of hemodialysis by noncoated dialyzer impaired flow-mediated vasodilation (P<0.05) associated with increased plasma levels of oxidized LDL (P<0.05), an index of oxidative stress. Hemodialysis by vitamin E-coated membrane prevented dialysis-induced endothelial dysfunction and increases in oxidized LDL. Plasma levels of oxidized LDL were inversely correlated with the magnitudes of flow-mediated vasodilation (r=-0.53, P< 0.001). Hemodialysis by noncoated or vitamin E-coated membrane did not affect glyceryl trinitrate-induced endothelium-independent vasodilation. CONCLUSIONS: Our findings indicate that hemodialysis per se impairs endothelial function, possibly by increasing oxidative stress.

Adult↗
PubMed2000

Neutrophil elastase inhibitor, ONO-5046 suppresses ozone-induced airway mucus hypersecretion in guinea pigs.

To investigate the role of neutrophil elastase in ozone-induced airway hypersecretion, we measured goblet cell secretion by using a semiquantitative morphometric technique in guinea pigs. The magnitude of mucus discharge was estimated from the mucus score, which is inversely related to the degree of mucus discharge in histological sections of trachea stained for mucus glycoprotein with periodic acid Schiff/Alcian blue. Mucus hypersecretion of goblet cells was induced by ozone exposure and persisted for up to 5 h after exposure. Pretreatment with N-[2-¿4-(2,2-dimethyl-propionyloxy) phenyl-sulfonylamino¿ benzoyl] aminoacetic acid (ONO-5046), a specific neutrophil elastase inhibitor (200 mg/kg, intraperitoneally), significantly inhibited goblet cell hypersecretion both just after and 5 h after ozone-exposure, but the latter inhibition was not complete. In bronchoalveolar lavage fluid, ozone exposure significantly increased the number of neutrophils just after and 5 h after exposure, while ONO-5046 significantly inhibited the increase in neutrophils only 5 h after ozone-exposure. These results indicate that neutrophil elastase may play an important role in the ozone-induced tracheal goblet cell hypersecretion and influx of neutrophils.

Animals↗
PubMed2000

Increased D-type cyclin expression together with decreased cdc2 activity confers megakaryocytic differentiation of a human thrombopoietin-dependent hematopoietic cell line.

At the late phase of megakaryocytopoiesis, megakaryocytes undergo endomitosis, which is characterized by DNA replication without cell division. Although a number of cell cycle regulatory molecules have been identified, the precise roles of these molecules in megakaryocytic endomitosis are largely unknown. In a human interleukin-3-dependent cell line transfected with the thrombopoietin (TPO) receptor c-mpl (F-36P-mpl), either treatment with TPO or the overexpression of activated ras (Ha-Ras(G12V)) induced megakaryocytic maturation with polyploid formation. We found that TPO stimulation or Ha-Ras(G12V) expression led to up-regulation of cyclin D1, cyclin D2, and cyclin D3 expression. In addition, expression levels of cyclin A and cyclin B were reduced during the total course of both TPO- and Ha-Ras(G12V)-induced megakaryocytic differentiation, thereby leading to decreased cdc2 kinase activity. Neither the induced expression of cyclin D1, cyclin D2, or cyclin D3 nor the expression of a dominant negative form of cdc2 alone could induce megakaryocytic differentiation of F-36P-mpl cells. In contrast, overexpression of dominant negative cdc2 together with cyclin D1, cyclin D2, or cyclin D3 facilitated megakaryocytic differentiation in the absence of TPO. These results suggest that both D-type cyclin expression and decreased cdc2 kinase activity may participate in megakaryocytic differentiation.

CDC2 Protein Kinase↗
PubMed2000

GD3 synthase gene expression in PC12 cells results in the continuous activation of TrkA and ERK1/2 and enhanced proliferation.

A rat pheochromocytoma cell line (PC12) transfected with ganglioside GD3 synthase gene showed a marked change in the ganglioside profile and enhanced proliferation and no response of neurite extension to nerve growth factor (NGF) stimulation. In these transfectant cells, a continuous phosphorylation of TrkA and the activation of ERK1/2 without NGF treatment were observed. Proliferation inhibition experiments with kinase inhibitors such as herbimycin A, K-252a, and PD98059 revealed that the enhanced proliferation was actually due to the activation of the Ras/MEK/ERK pathway. A TrkA dimer was detected in the GD3 synthase transfectant cells regardless of NGF treatment by cross-linking and immunoblotting. The increased expression of GD1b and GT1b in these transfectant cells might induce the conformational change of TrkA to form a dimer and to be activated continuously. These results may indicate regulatory roles of gangliosides in cell proliferation under physiological and malignant processes.

Animals↗
PubMed2000

Expression of apoptosis-regulatory genes in epithelial cells in pulmonary fibrosis in mice.

Up-regulation of Fas and Fas ligand and excessive apoptosis of bronchiolar and alveolar epithelial cells were identified in bleomycin-induced pulmonary fibrosis in mice. This study hypothesized that apoptosis-regulatory genes other than Fas-Fas ligand, such as p53, p21 (Waf1/Cip1), bcl-2, bcl-x, and bax, may also participate in epithelial cell apoptosis in this model. The expression of these genes was assessed by reverse transcription polymerase chain reaction (RT-PCR), RT in situ PCR, or immunohistochemistry. The expression of p53 and p21 mRNA was concurrently up-regulated in the alveolar epithelial cells at 1 h to 7 days after intratracheal instillation of bleomycin. The expression of bcl-2 mRNA was weakly up-regulated at 1 h to 14 days, while the expression level of bcl-2 protein was not changed. The expression of bcl-x(L) and bax mRNA was strongly up-regulated at 1 h to 7 days. The expression of bcl-x protein was up-regulated in lymphocytes and macrophages, whereas bax protein was up-regulated in both epithelial and inflammatory cells. It is concluded that epithelial cell apoptosis in this model may also be induced by the up-regulation of p53 and bax and by the imbalance between apoptosis-inducible and -inhibitory genes, in addition to the up-regulation of the Fas-Fas ligand pathway.

Animals↗
PubMed2000

A newly designed tensile tester for cells and its application to fibroblasts.

A tensile test system for cells has been designed and applied to fibroblasts from the rabbit patellar tendon. It consists of a thermostatic test chamber, an inverted fluorescence microscope, micromanipulators, a direct drive linear actuator, a cantilever-type load cell, and a video dimension analyzer (VDA). The test chamber and the microscope are mounted on a vibration isolator. A cell floated in Hanks' balanced salt solution of 37 degrees C is gripped with a pair of micropipettes which have very fine tips (outer diameter = 20 approximately 30 microm, inner diameter = 3 approximately 5 microm) and are coated with a cell adhesive, Cell-Tak, at their ends. One of the micropipettes is fixed to the load cell; the other one is attached to the linear actuator which is used to stretch the cell. Load applied to the cell is measured with the load cell, while elongation of the cell is determined with the VDA using the images of the ends of the micropipettes as markers. The measurement accuracy of the load cell was +/-0.05 microN. All the fibroblasts tested were firmly attached to the micropipettes during tensile testing, and showed local non-uniform deformation. The maximum load and elongation to failure of the cells were 0.9+/-0.2 microN and 86+/-24 microm, respectively.

Animals↗
PubMed2000

Stressful delivery influences circulating thrombopoietin (TPO) levels in newborns: possible role for cortisol in TPO-mpl binding.

The regulation mechanism of circulating thrombopoietin (TPO) level in human newborns remains unknown. In the present study, we examined whether the TPO concentrations in cord blood were influenced by the difference in the delivery method and the presence or absence of maternal/fetal complications. Cortisol levels were simultaneously measured to assess the adrenal response of fetuses. Both the TPO level and the cortisol level were substantially greater in the neonates delivered vaginally with and without the complications than in those delivered by cesarean section without the complications. The binding assay showed that the incubation of mpl(+)/BaF3 cells with cortisol gave rise to a significant decrease in the binding sites of TPO. These results suggest that the stress to the fetuses near the time of delivery affects the cord blood TPO levels, which may be mediated in part by the action of cortisol on the TPO-mpl binding system.

Binding Sites↗
PubMed2000

Tetrahydrobiopterin restores endothelial function in long-term smokers.

OBJECTIVES: We sought to test whether tetrahydrobiopterin (BH4) supplementation improves nitric oxide (NO) bioactivity in smokers. BACKGROUND: In smokers, endothelium-derived NO bioactivity is impaired. BH4 is an essential cofactor of NO synthase, and its deficiency decreases NO bioactivity. METHODS: Sapropterin hydrochloride, an active analogue of BH4 (2 mg/kg body weight), was administered orally to healthy male smokers and age-matched nonsmokers. Before and 3 and 24 h after sapropterin, we measured plasma levels of BH4 and examined flow-mediated vasodilation (FMV) of the brachial artery by high resolution ultrasonography, a noninvasive test of endothelial function. RESULTS: Basal plasma levels of BH4 were not different between smokers and nonsmokers. Sapropterin administration increased plasma levels of BH4 by threefold at 3 h, which returned to the baseline at 24 h. Before sapropterin, FMV was significantly smaller in smokers (p = 0.0002). Sapropterin significantly augmented endothelium-dependent vasodilation in smokers, but did not affect it in nonsmokers (p = 0.001 by analysis of variance [ANOVA]). Coadministration of N(G)-monomethyl-L-arginine (L-NMMA), an NO synthase inhibitor (20 micromol), into the brachial artery completely abolished the vasodilatory effects of sapropterin (p = 0.002 by ANOVA). Endothelium-independent vasodilation by glyceryl trinitrate was not different between smokers and nonsmokers and was not altered by BH4. CONCLUSIONS: We demonstrated that BH4 supplementation improved bioactivity of endothelium-derived NO in smokers. These observations strongly suggest that decreased NO-dependent vasodilation in smokers could be related to reduced bioactivity of BH4.

Administration, Oral↗
PubMed2000

Bilateral transcapholunate dislocation.

An uncommon case has been reported of bilateral transscaphoid-perilunate dislocation fracture following trauma. A 35-year-old male with bilateral transscapholunate dislocation was treated by closed reduction and internal fixation. The case was examined in detail, and compared to the findings in the literature; observations regarding fracture prognosis were also made. Two years post-surgery, the patient remained asymptomatic.

Accidental Falls↗
PubMed2000

Outcome following a population screening programme for oral cancer and precancer in Japan.

The purpose of this study was to evaluate the validity and outcome of an oral mucosal screening programme conducted in Japan. All adults over the age of 40 years resident in Tokoname city were invited by letter to attend a free general health screen and oral examinations annually. Twenty- to 39-year-old females were also encouraged to participate. During the years 1996-98, a total of 19056 subjects (5885 male, 13171 female: mean age 60.7+/-11.3 years) were examined by three types of screeners: postgraduate dental residents (n=17), hospital dentists (n=5) and general dental practitioners (n=15). In the cohorts examined screening dentists recorded oral mucosal lesions in 783 (4.1%) subjects. Of those detected with mucosal lesions, 200 (25.5%) were referred and 137 (68. 5%) attended for follow up examination in hospital departments by specialists with full diagnostic back up facilities. Thirty-nine subjects were confirmed as having oral cancer or precancer (two squamous cell carcinomas, 37 leukoplakias) and 40 with lichen planus. Five false positives (3.6%) were found. Among the cases referred under other diagnostic labels no cancers were detected. Among those who attended for confirmation of oral cancer or precancer by a specialist, sensitivity, specificity and positive predictive value were 0.92, 0.64 and 0.78, respectively. In males with oral cancer/leukoplakia, the prevalence of smoking, drinking and combined habits was higher than those with lichen planus or among negative subjects. The sensitivity and specificity determined from this research suggests that the performance of the Japanese dentists employed in screening was satisfactory. An attendance of 68% for re-examination by specialists compares well with other reported studies measuring patient compliance.

Adult↗