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Biomedical subjects

Y Miyamoto

Publications and source records attributed to Y Miyamoto.

At least 55 records · Page 3Linked to original sources
PubMed2001

Characterization of human taurine transporter expressed in insect cells using a recombinant baculovirus.

A recombinant baculovirus system was used to express the human taurine transporter in Sf9 cells and characterize its mediated uptake activity. This uptake process exhibited: (i) Na(+) dependence, (ii) larger inhibition of taurine transport by competing beta-amino acids than by alpha- and gamma-amino acids, (iii) apparent Michaelis constant, K(t), for taurine transport of 1.6 +/- 0.2 microM, and (iv) a maximal velocity, V(max), of 262 +/- 18 pmol/mg protein per 15 min. Coexpression of a molecular chaperone, human calnexin, enhanced taurine transporter activity by 43%. During development of taurine transporter expression, exposure to tunicamycin (10 microg/ml) decreased taurine transport activity by 76%. The taurine transporter linked to glutathione S-transferase (GST) was expressed to determine whether this conjugate also elicits taurine transport activity. Even though transport activity was markedly decreased, its Na(+) dependence was still evident. Coexpression of calnexin enhanced expression of this conjugated transporter activity by 54%. Immunoblot analysis revealed that calnexin did not change the amount of GST-taurine transporter conjugate or its molecular mass (i.e., 58.4-68.0 kDa). However, tunicamycin decreased its molecular mass. Taken together, taurine transport activity in a baculovirus expression system has characteristics similar to its wild-type counterpart. Stimulation of transport activity by coexpression with calnexin suggests the importance of transporter folding for optimal transport activity. Glycosylation of the transporter also increases its transport activity. Finally, GST-taurine transporter conjugate usage may aid transporter purification even though its transport activity decreases.

Animals↗
PubMed2001

Quantitative analysis of microchimerism in systemic sclerosis skin tissue.

It has been reported that more male DNA of presumed fetal origin is present in the blood and skin of women with systemic sclerosis (SSc) as compared with healthy controls after delivery, but these findings are controversial. We sought to determine whether male cell DNA is present in SSc using a quantitative polymerase chain reaction for Y chromosome DNA. The study groups comprised 57 healthy women, 49 patients with SSc and 30 patients with connective tissue diseases other than SSc who had given birth to at least one son and/or had experienced fetal loss. The intensity of the PCR bands on negatives of gel photographs was quantified with a video densitometer linked to a computer analysis system. Positive Y chromosome DNA was found in 20 healthy women, 14 SSc patients and 6 patients with connective tissue diseases other than SSc. The occurrence rate of DNA equivalents of male cells among the three groups showed no significant differences. The number of male cell DNA equivalents per 80 ng tissue DNA in SSc patients (4.59+/-9.63), however, was significantly higher than in healthy women (1.83+/-4.96; P < 0.05) and in patients with connective tissue diseases other than SSc (0.27+/-0.64; P < 0.01). The occurrence rate of fetal loss in male cell DNA-positive SSc (eight) was significantly higher than in male cell DNA-negative SSc patients (four; P < 0.01). No correlation was found between the number of male cell DNA equivalents and birth of sons or clinicolaboratory findings. These results indicate that the elevated amount of male cell DNA in SSc skin tissue may contribute to the pathogenesis of SSc.

Adult↗
PubMed2001

Successful treatment of mucoepidermoid carcinoma of the carina.

We successfully treated a 33-year-old man with mucoepidermoid carcinoma at the carina. Through preoperative spiral computed tomography with multiplanar and three-dimensional reconstructions, the lesion extended along the right main bronchus across the orifice of the right upper lobe. He underwent a carinal resection plus right upper lobectomy and reconstruction of the carina. He shows neither anastomotic complication nor recurrence of disease 1 year after surgery. Spiral computed tomography was used to evaluate the preoperative and postoperative state of the central airway.

Adult↗
PubMed2001

Characterization of cardiac myocyte and tissue beta-adrenergic signal transduction in rats with heart failure.

OBJECTIVE: The cellular basis of alterations in beta-adrenergic signal transduction in rats with chronic heart failure (CHF) remains unclear. The aim of the present study was to examine this signal transduction system in isolated ventricular cardiomyocytes of rats with CHF. We focused on changes in the levels of stimulatory (Gs) and inhibitory G-proteins (Gi). METHODS: CHF was induced in male Wistar rats by coronary artery ligation (CAL). Hemodynamic and biochemical parameters were measured 8 weeks after CAL. Alterations in contractile function and Ca(2+) transients via beta-adrenergic receptor signaling of cardiomyocytes isolated from rats with CHF were characterized by simultaneous measurements of cell shortening and fura-2 fluorescence intensity. RESULTS: Coronary artery-ligated rats showed symptoms of CHF, such as decreased contractile function, increased left ventricular volume, decreased chamber stiffness, and about 40% infarct formation of the left ventricle, by 8 weeks after surgery. The contractile function and Ca(2+) dynamics of cardiomyocytes from the rats with CHF remained normal under basal conditions. Only cardiac cell length was increased. The responses of peak shortening, fura-2 fluorescence ratio amplitude, and cAMP content to beta-adrenoceptor stimulation were reduced in cardiomyocytes of the rats with CHF, whereas direct stimulation of adenylate cyclase did not affect the response of these variables. Cardiomyocyte Gsalpha protein was decreased, whereas no changes in Gialpha proteins were seen in these cells. Increases in tissue Gsalpha and Gialpha proteins in the scar zone were detected. The results on tissue levels of collagen and G-proteins in the viable left ventricle appeared to depend on the presence of nonmyocytes. CONCLUSIONS: The results suggest that impaired contractile function of cardiomyocytes is unlikely to account for global LV contractile dysfunction, and that down-regulation of beta-adrenoceptors occurs in cardiomyocytes per se. The difference in changes of G-protein between the cardiomyocyte and myocardial tissue suggests an appreciable contribution of nonmyocytes to myocardial G-protein levels.

Animals↗
PubMed2001

Age-related changes in cholinergic and purinergic neurotransmission in human isolated bladder smooth muscles.

We evaluated the correlation among age, cholinergic and purinergic neurotransmissions in the electrical field stimulation-induced contractions in human isolated urinary bladder smooth muscles, using the muscle bath technique. Human bladder specimens were divided into three groups (G1, under 50years; G2, 51-70years; G3, over 70years old), and each muscle strip was suspended in a thermostatically controlled organ bath filled with oxygenated Krebs-Henseleit solution, connected to an isometric force displacement transducer, and an isometric tension development was recorded. The contractile responses induced by KCl, carbachol, adenosine triphosphate (ATP) and electrical field stimulation, and the effects of atropine and alpha, beta methylene ATP on electrical field stimulation-induced contractions were observed. The contractile response to KCl and concentration-response curves for carbachol and ATP, and frequency-response curves for electrical field stimulation were not significantly different among the three groups. The atropine sensitive and resistant parts of contraction induced by electrical field stimulation were decreased and increased with age, respectively. There are significant positive and negative correlations between age and the purinergic, and age and the cholinergic neurotransmissions in human isolated bladder smooth muscles, respectively. The age-related changes in neurotransmissions may contribute to the changes in bladder function in the elderly.

Adenosine Triphosphate↗
PubMed2001

Ultrasound virtual endoscopic imaging.

Volume data acquisition, three dimensional (3D) imaging, and multiplanar reformatting have become widely used for computed tomography (CT) and magnetic resonance imaging (MRI). As an extension of this technology, virtual endoscopic visualization of hollow organs has become a reality that is now finding its way into clinical CT practice. The same methods of computer processing as are used for CT and MRI can be applied to an ultrasound (US) volume image data set with the same potential output; namely, 3D, multiplanar, and virtual endoscopic images. The use of this image processing technology for US applications has lagged behind the CT and MRI applications, but considerable progress in applying these methods to US has occurred in recent years. As a result, US virtual endoscopic imaging now can be performed on a clinical basis by using standard US instruments and commercially available computer software. The use of newer US imaging methods, such as tissue harmonic and power Doppler imaging, has enhanced the potential for US virtual endoscopy. This article reviews the technology of US virtual endoscopy. In addition, our preliminary experience of using this method for abdominal and vascular diagnosis is described. Finally, we speculate on technical improvements and potential applications that are likely in the future.

Acoustics↗
PubMed2001

Gastric neuropeptides and gastric motor abnormality in streptozotocin-induced diabetic rats: observation for four weeks after streptozotocin.

Alterations of gastric calcitonin gene-related peptide and substance P content and gastric emptying in early stages of streptozotocin-induced diabetic rats were investigated. Diabetes was induced by intravenous injection of streptozotocin (50 mg/kg) in male Wistar rats. Gastric emptying of phenol red solution and calcitonin gene-related peptide and substance P content of gastric walls, measured by radioimmunoassay, was assessed two and four weeks after streptozotocin injection. Gastric emptying two weeks after streptozotocin was delayed (32+/-9%) and that four weeks after was enhanced (73+/-2%) compared with nondiabetic control rats (50+/-3%). Calcitonin gene-related peptide content of the gastric antrum and corpus was increased two weeks after and decreased four weeks after streptozotocin, while gastric substance P content was not changed at any time in diabetic rats. Insulin treatment reversed alterations of gastric emptying and calcitonin gene-related peptide content. The delayed gastric emptying in two-week diabetic rats was reversed by CGRP antagonist and the enhanced gastric emptying in four-week diabetic rats was reversed by CGRP pretreatment. These results suggest a possible relationship between gastric calcitonin gene-related peptide and abnormal gastric motility in diabetic state.

Animals↗
PubMed2001

Tissue responses to anti-washout apatite cement using chitosan when implanted in the rat tibia.

The tissue response to anti-washout apatite cement using chitosan (aw-AC(chi)) was evaluated by implanting aw-AC(chi) into bone defects of rat tibiae using conventional apatite cement (c-AC) as a control material. During the experimental period up to 16 weeks, the only difference between aw-AC and c-AC was found at two weeks in the tissue response of soft tissue. At two weeks, c-AC showed a moderate inflammatory response; small particles of c-AC were scattered in the cutaneous tissue and many foreign body giant cells were collected around the scattered c-AC, whereas aw-AC showed only a slight inflammatory response and few foreign body giant cells. We found no difference between aw-AC(chi) and c-AC with respect to bone tissue response. Both AC were almost completely surrounded by mature bone at eight weeks. No promotion or reduction of osteoconductivity was observed by chitosan even though it is considered to promote bone formation. We concluded, therefore, that enhancement of bone formation cannot be expected by employing chitosan to obtain anti-washout properties, at least in the concentration used in this study, even though aw-AC(chi) is much more useful than c-AC.

Journal Article↗
PubMed2001

Frequency and clinical characteristics of dilated cardiomyopathy caused by desmin gene mutation in a Japanese population.

AIMS: Dilated cardiomyopathy is partly caused by a mutation of some cytoskeletal or nuclear envelope proteins. It has been confirmed recently that a missense mutation of the gene encoding desmin, a cytoskeletal protein, can cause dilated cardiomyopathy. This study was aimed at elucidating the frequency and clinical characteristics of dilated cardiomyopathy caused by desmin mutation. METHODS AND RESULTS: We examined 265 Japanese patients with dilated cardiomyopathy (217 sporadic cases and 48 probands of familial dilated cardiomyopathy). The exon 8 of the desmin gene, the critical region for the pathogenesis of dilated cardiomyopathy, was analysed by polymerase chain reaction, single-strand conformation polymorphism and sequencing. The same missense mutation (Ile451Met) as reported previously was detected in three patients (1.1%). All these patients were male and sporadic, and more likely to be accompanied by characteristics such as younger age at diagnosis, lower fractional shortening and ejection fraction than each mean value of sporadic cases. The chronological changes in cardiac function were inconsistent in the three patients. CONCLUSION: The missense mutation (Ile451Met) of the desmin gene can be the genetic cause of dilated cardiomyopathy, although with very low frequency. The ages at diagnosis were younger and the cardiac function had deteriorated further than general cases of sporadic dilated cardiomyopathy.

Adult↗
PubMed2001

Osmotic stress induces HB-EGF gene expression via Ca(2+)/Pyk2/JNK signal cascades in rat aortic smooth muscle cells.

The present study was undertaken in an attempt to clarify the pathway by which hyperosmotic stress induces HB-EGF gene expression in rat aortic smooth muscle cells (RASMC). Hyperosmotic stress induced by a high concentration of glucose or mannitol resulted in an increase in HB-EGF mRNA level in a dose- and time-dependent manner. HB-EGF induction was blocked by curcumin, a c-jun/fos antisense oligonucleotide and a dominant-negative mutant of JNK1. Electrophoretic mobility shift assay also showed the involvement of AP-1 in HB-EGF gene expression by glucose. In addition, hyperosmotic stress induced rapid phosphorylation of Pyk2 in RASMC. TPA and calcium chelating agents (BAPTA-AM and EGTA) blocked Pyk2 phosphorylation and HB-EGF gene expression. Furthermore, HB-EGF gene expression and JNK activation by hyperosmotic stress were sensitive to PP2, an Src kinase-specific inhibitor. These findings indicate that hyperosmotic stress activates JNK via calcium-Pyk2 signaling cascades, which in turn induce HB-EGF gene expression.

Animals↗
PubMed2001

Balloon catheter-assisted endoscopic sclerotherapy for gastric fundal varices using alpha-cyanoacrylate monomer.

We present two patients with bleeding episodes from gastric fundal varices. The gastric fundal varices were treated by balloon catheter-assisted endoscopic sclerotherapy using alpha-cyanoacrylate monomer. The varices were successfully obliterated with no complications or hemodynamic changes to the gastrorenal shunts. This procedure may be considered a novel, feasible approach to the treatment of gastric fundal varices in the future.

Aged↗
PubMed2001

The neuron-restrictive silencer element-neuron-restrictive silencer factor system regulates basal and endothelin 1-inducible atrial natriuretic peptide gene expression in ventricular myocytes.

Induction of the atrial natriuretic peptide (ANP) gene is a common feature of ventricular hypertrophy. A number of cis-acting enhancer elements for several transcriptional activators have been shown to play central roles in the regulation of ANP gene expression, but much less is known about contributions made by transcriptional repressors. The neuron-restrictive silencer element (NRSE), also known as repressor element 1, mediates repression of neuronal gene expression in nonneuronal cells. We found that NRSE, which is located in the 3' untranslated region of the ANP gene, mediated repression of ANP promoter activity in ventricular myocytes and was also involved in the endothelin 1-induced increase in ANP gene transcription. The repression was conferred by a repressor protein, neuron-restrictive silencer factor (NRSF). NRSF associated with the transcriptional corepressor mSin3 and formed a complex with histone deacetylase (HDAC) in ventricular myocytes. Trichostatin A (TSA), a specific HDAC inhibitor, relieved NRSE-mediated repression of ANP promoter activity, and chromatin immunoprecipitation assays revealed the involvement of histone deacetylation in NRSE-mediated repression of ANP gene expression. Furthermore, in myocytes infected with recombinant adenovirus expressing a dominant-negative form of NRSF, the basal level of endogenous ANP gene expression was increased and a TSA-induced increase in ANP gene expression was apparently attenuated, compared with those in myocytes infected with control adenovirus. Our findings show that an NRSE-NRSF system plays a key role in the regulation of ANP gene expression by HDAC in ventricular myocytes and provide a new insight into the role of the NRSE-NRSF system outside the nervous system.

3' Untranslated Regions↗
PubMed2001

Protective effect of heat shock protein 72 on contractile function of perfused failing heart.

The contribution of heat shock protein 72 (HSP72) to the protection of cardiac function was examined in rats with chronic heat failure (CHF) following coronary artery ligation (CAL). The CAL animals revealed functional deterioration without low cardiac output 2 wk after CAL and with low cardiac output 8 wk after CAL, suggesting that CHF had developed by 8 wk after CAL. The hearts isolated from animals 2 and 8 wk after CAL (2-wk CAL heart and 8-wk CAL heart, respectively) were subjected to hyperthermia (at 42 degrees C) for 15 min, followed by 6-h perfusion (hyperthermia/6-h perfusion). The 2-wk CAL heart showed a 19.0 +/- 3.9% decline in the rate- pressure product (RPP) after hyperthermia/6-h perfusion, similar to the nonoperated control (19.8 +/- 2.9% decline). The production of myocardial HSP72 increased in the 2-wk CAL heart in response to hyperthermia (412.7 +/- 29.5% of each prehyperthermia value). The 8-wk CAL heart showed a reduction in the RPP (45.2 +/- 4.3% decline) after hyperthermia/6-h perfusion, associated with blunting of the production of HSP72 (68.9 +/- 22.6% increase, respectively). The results suggest that functional deterioration of the isolated failing heart may be attributed to a reduction in the production of myocardial HSP72.

Animals↗
PubMed2001

Induction of nitric oxide synthase and subsequent production of nitric oxide not involved in interferon-gamma-induced hyperpermeability of Caco-2 intestinal epithelial monolayers.

Caco-2 cell monolayers exposed to 1000 U/ml interferon-gamma (IFN-gamma) for 6 days elicited inducible nitric oxide synthase (iNOS) expression and increased translayer permeability. This iNOS increase was blocked by pyrrolidinedithiocarbamate (an inhibitor of iNOS induction) but it did not suppress the hyperpermeability response. Furthermore, 2,2'-(hydroxynitrosohydrazino) bis-ethanamine (a NO donor) did not increase monolayer permeability. Therefore, IFN-gamma-induced hyperpermeability is not due to its induction of iNOS activity and resulting increases in NO levels.

Caco-2 Cells↗
PubMed2001

Comparison of bacteriological, genetic and pathological characters between Escherichia coli O115a,c:K(B) and Citrobacter rodentium.

Murine pathogenic Escherichia coli O115a,c:K(B) (MPEC) is the causative agent of mouse megaenteron, the pathology of which resembles that of transmissible murine colonic hyperplasia caused by Citrobacter rodentium. We compared their genetic and pathological features to reveal the relationship between these two bacteria. To evaluate the genetic distances, 16S rDNA genes were sequenced and biochemical reactions were tested. Mouse strain susceptibility tests, using CF1 MPEC-susceptible germfree mice and BALB/cA(Jic) resistant mice were performed. MPEC strains and C. rodentium showed more than 99.6% identity by comparison of 16S rDNA gene sequences. All results from biochemical reactions and the mouse strain susceptibility tests were identical. It is proposed that MPEC should be reclassified as C. rodentium.

Animals↗
PubMed2001

Color/power Doppler sonographic differential diagnosis of superficial lymphadenopathy: metastasis, malignant lymphoma, and benign process.

OBJECTIVE: Differentiation of lymph nodes as metastasis, malignant lymphoma, and benign lesions by gray scale and color/power Doppler ultrasonography has been reported. In this study we sought to determine patterns of abnormal vascularity, the relationship between diagnostic criteria and node size, and which vessel in the node was best suited for Doppler spectral analysis. Extrahilar vessels, defined as vessels entering through the lymphatic surface and not through the hilus, were also investigated. METHODS: One hundred twenty-nine nodes were examined by color/power Doppler ultrasonography. RESULTS: Extrahilar vessels were seen in 85.4% of metastatic, 40.5% of lymphomatous, and 7.7% of benign nodes regardless of node size. The mean pulsatility index and resistive index values of metastatic nodes were higher than those of benign nodes regardless of their size. Those of lymphoma were intermediate compared with the others. CONCLUSIONS: A pulsatility index greater then 1.3 and a resistive index greater than 0.72 suggested malignancy as measured from any vessel.

Breast Neoplasms↗