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Biomedical subjects

K Shirato

Publications and source records attributed to K Shirato.

At least 127 records · Page 7Linked to original sources
PubMed1998

Induction of L-histidine decarboxylase in a human mast cell line, HMC-1.

Histamine is an important mediator in allergic reactions, gastric acid secretions, and neurotransmission in the central nervous system. Basophils and mast cells are the main sources of histamine, which is formed from L-histidine by histidine decarboxylase (HDC). However, the regulatory mechanism of HDC in these cells remains unclear. We examined the regulation of HDC activity and gene expression using a unique human mast cell line, HMC-1, after stimulation with phorbol 12-myristate 13-acetate (PMA) or ionomycin. HDC activity was increased from 52.1+/-0.4 (mean+/-standard deviation) to 154+/-6.9, or 105.6+/-6.2 pmol/min/mg protein (n = 3), 4 hours after stimulation with PMA (10 ng/mL) or ionomycin (10[-6] M). Although actinomycin D had no effect on this increase, cycloheximide completely inhibited the increase caused by these stimuli. The population of HMC-1 cells containing HDC protein was increased after stimulation with either PMA or ionomycin as evaluated by immunocytochemical analysis with anti-HDC antibody as a marker. HMC-1 constitutively expressed HDC mRNA, and its level was not increased with these stimuli. These results suggest that the increase of HDC activity in HMC-1 induced by PMA or ionomycin is regulated at the translational level.

Cell Line↗
PubMed1998

[Antigen-induced airway hyperresponsiveness in infantile guinea pigs].

To investigate the development of airway hyperresponsiveness in infantile guinea pigs, animals (10 days old) were immunized twice and challenged by inhalation of 1% ovalbumin for 10 min with 7 days intervals. Similar to adult guinea pigs, infantile ones developed an increased airway responsiveness to acetylcholine 24 hr after antigen challenge. There was a marked increase in the number of total leukocytes, eosinophils and lymphocytes in bronchoalveolar lavage fluid (BALF). Suplatast tosilate (suplatast) and pemirolast potassium (pemirolast) given orally throughout the experiments suppressed the development of airway hyperresponsiveness in infantile animals. They showed similar potency in the suppression of eosinophil accumulation in BALF and lung tissue, while suplatast inhibited lymphocyte accumulation stronger than pemirolast. Collectively, the present model of airway hyperresponsiveness in infantile guinea pigs may be useful in predicting the efficacy of antiallergic agents in the treatment of asthmatic children.

Animals↗
PubMed1998

[Evaluation of therapy for dilated cardiomyopathy with heart failure by iodine-123 metaiodobenzylguanidine imaging: comparison with heart rate variability power spectral analysis].

The relationship between the myocardial uptake of iodine-123 metaiodobenzylguanidine (123I-MIBG) and heart rate variability parameters has not been determined. This study determined the relationship between the change in myocardial uptake of 123I-MIBG and improvement in left ventricular function after treatment, to determine the usefulness of 123I-MIBG imaging to assess the effect of therapy on heart failure due to dilated cardiomyopathy (DCM). 123I-MIBG imaging and power spectral analysis of heart rate variability were performed before and after treatment in 17 patients with heart failure due to DCM. The following parameters were compared before and after treatment: New York Heart Association (NYHA) functional class, radiographic cardiothoracic ratio (CTR), blood pressure, echocardiographic data [left ventricular end-systolic (LVDs) and end-diastolic (LVDd) diameters, left ventricular ejection fraction (LVEF)], plasma concentrations of norepinephrine and epinephrine, heart rate variability power spectral analysis data [mean low frequency (MLF) and high frequency power (MHF)] and the myocardium to mediastinum activity ratio (MYO/M) obtained in early and late images, and washout rate calculated by anterior planar imaging of 123I-MIBG. The NYHA functional class, LVEF, LVDs, CTR, MLF and MHF improved after treatment. Early MYO/M and late MYO/M improved after treatment. The rate of increase in late MYO/M was positively correlated with the rate of improvement of LVEF after treatment. Furthermore, the late MYO/M was negatively correlated with MLF. Washout rate revealed no correlation with hemodynamic parameters. These findings suggest that late MYO/M is more useful than washout rate to assess the effect of treatment on heart failure due to DCM. Furthermore, the 123I-MIBG imaging and heart rate variability parameters are useful to assess the autonomic tone in DCM with heart failure.

3-Iodobenzylguanidine↗
PubMed1997

TGF-beta induced by oral tolerance ameliorates experimental tracheal eosinophilia.

Induction of peripheral tolerance is one of the feasible approaches for the control of autoimmunities and allergies. Therapeutic applications of oral tolerance to autoimmunities are in progress both experimentally and clinically, while those to allergies have been poorly investigated. We examined the induction of CD4+ T cells with suppressive properties by oral tolerance and the mechanism by which these cells down-regulated Ag-induced eosinophilia in the trachea. Feeding of mice transgenic for anti-OVA TCR with high doses of OVA inhibited the airway eosinophilic inflammation induced by the intratracheally administered Ag. This inhibition reflected the mechanism of active suppression, since the inhibitory effect was adoptively transferred by splenic CD4+ T cells from the transgenic mice fed with high doses of OVA. The Ag specificity of the suppressor T cells was documented by the failure of spleen cells from mice that were orally tolerant of OVA to suppress irrelevant Ag, KLH-specific airway eosinophilic inflammation. The suppressive effect of the transferred T cells on eosinophil recruitment was neutralized by anti-TGF-beta mAb, but not anti-IFN-gamma mAb, indicating that the suppression is due to the inhibitory effect by secreted TGF-beta, but not to the dominance of the transferred Th1 cells over Th2 cells. This is the first study to reveal a link between oral tolerance and the regulation of Th2-mediated experimental tracheal eosinophilia through TGF-beta. Our experimental model suggests possible therapeutic applications of oral tolerance for the treatment of allergic disorders such as bronchial asthma.

Adoptive Transfer↗
PubMed1997

Role of cyclic ADP-ribose in ATP-activated potassium currents in alveolar macrophages.

There is growing evidence that extracellular ATP causes a dramatic change in the membrane conductance of a variety of inflammatory cells. In the present study, using the nystatin perforated patch recording configuration, we found that ATP (0.3-30 microM) induced a transient outward current in a concentration-dependent manner and that the reversal potential of the ATP-induced outward current was close to the K+ equilibrium potential, indicating that the membrane behaves like a K+ electrode in the presence of ATP. The first application of ATP to alveolar macrophages perfused with Ca2+-free external solution could induce the outward current, but the response to ATP was diminished with successive applications. Intracellular perfusion with a Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid, also diminished the response. When cyclic ADP-ribose (cADPR) was applied to the macrophage cytoplasm, a transient outward current was elicited. Thereafter, the successive outward current was inhibited, suggesting the involvement of cADPR in the response. Intracellular perfusion with inositol 1,4, 5-trisphosphate also induced a transient outward current, but the successive current was not inhibited. The ATP-induced outward current was abolished when 8-amino-cADPR (as a blocker of cADPR, 10(-6)-10(-5) M) was introduced into the cytoplasm. Homogenates of alveolar macrophages showed both ADP-ribosyl cyclase and cADPR hydrolase activities, and CD38 (ADP-ribosyl cyclase/cADPR hydrolase) expression was confirmed by reverse transcriptase-polymerase chain reaction and Western blot analyses. These results indicate that ATP activates K+ currents by releasing Ca2+ from cADPR-sensitive internal Ca2+ stores.

Adenosine Diphosphate Ribose↗
PubMed1997

Signature current of SO2-induced bronchitis in rabbit.

To investigate abnormalities of airway epithelial ion transport underlying chronic inflammatory airway diseases, we performed electrophysiological, histological, and molecular biological experiments using rabbits exposed to SO2 as a model of bronchitis. By comparison with control, the SO2-exposed trachea exhibited decreased short circuit current (Isc) and conductance associated with increased potential difference. In normal trachea, apical ATP induced a transient Isc activation followed by a suppression, whereas the bronchitis model exhibited a prolonged activation without suppression. This pathological ATP response was abolished by diphenylamine 2-carboxylate or Cl--free bath solution. A significant increase in net Cl- flux toward the lumen was observed after ATP in our bronchitis model. Isoproterenol or adenosine evoked a sustained Isc increase in SO2-exposed, but not in normal, tracheas. The Northern blot analysis showed a strong expression of cystic fibrosis transmembrane conductance regulator (CFTR) mRNA in SO2-exposed epithelium. The immunohistochemical study revealed a positive label of CFTR on cells located luminally only in SO2-exposed rabbits. We concluded that the prolonged ATP response in our bronchitis model was of a superimposed normal and adenosine-activated current. The latter current was also activated by isoproterenol and appeared as a signature current for the bronchitis model airway. This was likely mediated by CFTR expressed in the course of chronic inflammation.

Adenosine↗
PubMed1997

FMLP actions and its binding sites in isolated human coronary arteries.

The chemoattractant f-Met-Leu-Phe (FMLP) can modulate human coronary arterial tone without the involvement of peripheral leukocytes. We investigated the actions of FMLP and its cellular mechanism in human coronary arteries isolated 2-3 h after death. A single dose of FMLP (0.01-10 microM) produced transient contraction (or, followed by relaxation) responses in most human coronary rings examined. These responses to FMLP were in large part mediated by the generation of cyclooxygenase products, mainly thromboxane A2 (TXA2) and prostaglandin I2 (PGI2). Radiolabeled N-formyl hexapeptide. 125I-f-Nle-Leu-Phe-Nle-Tyr-Lys bound densely to intimal and adventitial sites that accumulated macrophages (CD68-positive) with a Kd of 14-29 nM and, further, weakly to the media with a Kd of 2.4-3.6 microM. Several cell types including macrophages, endothelial cells and smooth muscle cells were positively immunostained for both TXA2 synthase and PGI2 synthase. However, there was no significant relation between the magnitude of the responses to FMLP and dense macrophage accumulation in the intimal plaques or the adventitia. A reverse transcription-polymerase chain reaction showed predominant expression of FMLP receptor homologues, FPRH1 and FPRH2 mRNA, in human coronary medial tissues relative to that in leukocytes. In conclusion. FMLP produced transient tension changes in human coronary arteries, mainly via the generation of TXA2 and PGI2. This effect of FMLP did not appear to be mediated by the activation of densely accumulated intimal and/or adventitial macrophages, but by the activation of unidentified medial tissue cells which might have functional FMLP receptor homologues.

Adolescent↗
PubMed1997

A case of Sjögren's syndrome associated with Sweet's syndrome.

We report a case of Sjögren's syndrome whose clinical course had been indolent until the patient presented with Sweet's syndrome (acute febrile neutrophilic dermatosis). This patient showed renal failure and renal tubular acidosis. Sweet's syndrome resolved within 3 weeks without corticosteroid therapy. Renal biopsy findings were consistent with interstitial nephritis. His renal manifestations responded to corticosteroid therapy and the renal function remained stable during 6 years follow-up without recurrence of Sweet's syndrome. Although close association of both syndromes is already known, in our case Sjögren's syndrome may have been exacerbated by occurrence of Sweet's syndrome.

Acute Kidney Injury↗
PubMed1997

Anti-atherogenicity in women does not prevent restenosis after balloon angioplasty.

To test the hypothesis that anti-atherogenicity in women exerts beneficial effects to prevent restenosis formation after coronary angioplasty, we studied 493 men (988 lesions) and 81 women (159 lesions), aged 40-60 years, who had undergone successful balloon angioplasty and had follow-up angiography, 4.9 +/- 4.1 months later. We compared the extent of restenosis between men and women, and between pre- and post-menopausal women, which was assessed by a categorical definition of restenosis (more than 50% diameter stenosis at follow-up) and by percent diameter measured immediately after angioplasty and at follow-up. Hypertension was more frequent in women and a significantly lower percentage of women smoked. In women, the levels of total cholesterol and low-density lipoprotein cholesterol were higher. The location of dilated lesions, frequency of angioplasty for lesions with chronic total occlusion, and frequency of emergency angioplasty in patients with unstable angina or acute myocardial infarction were similar in men and women. Restenosis formation, estimated by the categorical definition or percent diameter, did not differ between men and women, or between pre- and post-menopausal women. Menopausal status or sex was not an independent predictor of restenosis by multivariate analysis. Thus, the benefit of anti-atherogenicity in women does not play an important role in preventing restenosis after coronary angioplasty.

Adult↗
PubMed1997

Detection of surfactant protein-A gene transcript in the cells from pleural effusion for the diagnosis of lung adenocarcinoma.

PURPOSE: To determine whether detecting surfactant protein-A (SP-A) gene transcript in the cells from pleural effusion is useful for the diagnosis of lung adenocarcinoma. PATIENTS AND METHODS: We performed reverse transcription polymerase chain reaction (RT-PCR) analysis of SP-A gene transcript in the cells of pleural effusion from 42 consecutive patients with pleural effusion, including 7 patients with primary lung adenocarcinoma before their treatments. RESULTS: A cDNA segment of SP-A was amplified from the pleural fluid cells of all patients with primary lung adenocarcinoma, indicating the presence of the SP-A gene transcript. None of the remaining patients, including those with metastatic lung adenocarcinoma, showed positive for the SP-A gene transcript. CONCLUSION: These findings indicate that RT-PCR analysis of the SP-A gene transcript in pleural effusion is useful for the diagnosis of primary lung adenocarcinoma.

Adenocarcinoma↗
PubMed1997

ATP-induced Cl- secretion with suppressed Na+ absorption in rabbit tracheal epithelium.

The effect of extracellular ATP on ion transport of rabbit tracheal epithelium was examined using an Ussing chamber. Isoproterenol (10(-8)-10(-5) M) did not alter the electrophysiological properties across the tracheal epithelium. Apically applied ATP induced an initial transient increase in short circuit current (SCC) followed by a decline to below the prior baseline. The initial increase by ATP (10(-4) M) was significantly inhibited by a Cl(-) -channel inhibitor diphenylamine-2-carboxylate (DPC, 5 x 10(-4) M) and Cl(-) -substitution with gluconate in the bath solution, while a cystic fibrosis transmembrane regulator (CFTR) Cl(-) -channel inhibitor glibenclamide (10(-4) M), a Na(+)-channel inhibitor amiloride (10(-4) M) and a K(+) -channel inhibitor quinidine (10(-4) M) all failed to alter it. The decline in SCC by ATP was abolished by amiloride, while DPC or Cl-substitution with gluconate in the bath solution did not alter it. Ca(2+)-removal from the bath solutions did not significantly alter the initial increase nor the decline by ATP. Ionomycin (10(-5) M) induced an initial transient increase in SCC, to a degree similar to that by ATP alone. A calmodulin antagonist W-7 reduced the SCC baseline and abolished SCC increase by ATP. These findings indicate that ATP activates Ca(2+)-dependent Cl(-) -channels with an inhibition of Na -channel activity or absorption in rabbit tracheal epithelium.

Adenosine Triphosphate↗
PubMed1997

HMT regulates histamine-induced glycoconjugate secretion from human airways in vitro.

To determine whether histamine N-methyltransferase (HMT) regulates mucus glycoprotein (MGP) secretion from airways, we examined the effect of an HMT inhibitor, SKF 91488, on MGP secretion from human airways in vitro. MGP secretion from human airway explants (with epithelium) and isolated submucosal glands was estimated by measuring trichloroacetic acid (TCA) precipitable glycoconjugates using secretory indices. Histamine induced significant MGP secretion from both explants and isolated glands. Pretreatment with SKF 91488 significantly inhibited histamine-induced secretion from explants, while it did not alter significantly the secretion from isolated glands. H1-blocker significantly reversed the inhibition by SKF 91488 of the secretion from explants, while H2-blocker abolished histamine-induced secretion from both explants and isolated glands. Prostaglandin E2 (PGE2) significantly inhibited histamine-induced secretion from isolated glands. The inhibitory action of SKF 91488 in airway explants was blocked by indomethacin and was significantly reduced by a prostanoid EP4 receptor antagonist (AH23848B). These findings suggest that HMT regulates MGP secretion from human airway submucosal glands through an interaction with epithelial cells which involves the release of PGE2.

Animals↗
PubMed1997

Thrombin stimulates production of transforming growth factor-beta by cultured human mesangial cells.

Fibrin formation within the glomeruli occurs in various forms of human and experimental glomerulonephritis and it may play an important role in progressive glomerular injury. Transforming growth factor-beta (TGF-beta) has been shown to participate in the glomerular accumulation of extracellular matrix in glomerulonephritis. We investigated whether thrombin, an important coagulation factor, could modulate the production of TGF-beta by cultured human mesangial cells (HMC). TGF-beta levels in the culture supernatants were measured by ELISA using a specific antibody. The TGF-beta concentration was significantly increased by incubation of HMC with thrombin in a time-dependent manner. The stimulating effect of thrombin on TGF-beta was inhibited by addition of hirudin (a natural thrombin inhibitor) and argatroban (a synthetic thrombin inhibitor). In addition DFP-inactivated thrombin, which has no enzymatic activity, did not stimulate TGF-beta production. A protein kinase C inhibitor (H7) and a tyrosine kinase inhibitor (herbimycin A) also inhibited thrombin induced TGF-beta production. These findings suggested that thrombin may modulate the synthesis of TGF-beta via protein kinase C- and tyrosine kinase-dependent mechanisms in cultured HMC. Thus thrombin may participate in the accumulation of extracellular matrix in glomeruli through the augmentation of TGF-beta production.

Cells, Cultured↗
PubMed1997

Role of cytosolic Ca2+ and protein kinase C in developing myogenic contraction in isolated rat small arteries.

Cytosolic Ca2+ and protein kinase C (PKC) may regulate the myogenic contraction of arterial myocytes. The role of these second messengers is examined in skeletal muscle small arteries, which have strong myogenic activity, and mesenteric small arteries, which have weak myogenic activity. The vessels were isolated and cannulated. The inner diameter was measured with a video-digitizing system. Cytosolic Ca2+ concentration was assessed by fura 2. Skeletal muscle small arteries dilated from 122 +/- 6 to 153 +/- 6 microm immediately after the transmural pressure change from 40 to 100 mmHg and constricted to 121 +/- 5 microm (myogenic contraction) with an increase in the 340/380 fluorescence ratio (by approximately 33%) in control vessels. Nifedipine abolished myogenic contraction and the increase in the fluorescence ratio. PKC inhibitors (H7 and staurosporine) abolished myogenic contraction but did not depress the increase in the fluorescence ratio. In mesenteric small arteries, myogenic contraction was insignificant in control vessels. A relatively low dose of PKC activator (4.4 +/- 1.4 nmol/l) elicited myogenic contraction, but a higher dose (21 +/- 6 nmol/l) depressed it. Thus the cytosolic Ca2+ increase and PKC activity may cooperatively act on the myogenic contraction of skeletal muscle small arteries. The activity of PKC should play an important role in myogenic contraction of rat small arteries.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1997

Lack of ventilatory threshold in patients with chronic obstructive pulmonary disease.

We investigated whether the ventilatory threshold (VET) could be detected in 25 patients with severe chronic obstructive pulmonary disease (COPD). Exercise on a treadmill was performed until symptom-limited maximum oxygen uptake (VO2SL) was obtained. VET was absent in 14 patients (56%, VET(-) group) and present in the others (44%, VET(+) group). Basal pulmonary functions and dyspnea index (VE,SL/MVV) were not different between the two groups. Endurance time and exercise tolerance (VO2SL/bw) were significantly less in VET(-) than in VET(+). In the former group, PaO2 and pH at maximal exercise decreased and PaCO2 increased significantly, but HCO3- did not change compared with the corresponding values before exercise. In the latter group, PaCO2 at maximal exercise increased significantly, and pH and HCO3- decreased significantly compared with the values before exercise, but PaO2 did not. The changes in PaO2 and PaCO2 were not different between the two groups, but changes in pH and HCO3- in VET(+) were greater than those in VET(-). These results suggest that the absence of VET in some COPD patients indicates a lower exercise capacity without producing metabolic acidosis. This may be caused by rapidly developing dyspnea.

Aged↗
PubMed1997

Dexamethasone suppressed gene expression and production of interleukin-10 by human peripheral blood mononuclear cells and monocytes.

Interleukin-10 (IL-10) is known to inhibit T cell-mediated responses. IL-10 has also been shown to play an important pathogenetic role in allergic diseases. Glucocorticoid is known to inhibit the production and gene expression of many cytokines which induce inflammatory reactions. We examined the effect of dexamethasone on the gene expression and production of IL-10 by human peripheral blood mononuclear cells (PBMCs) and monocytes. PBMCs and monocytes from 5 healthy volunteers were incubated with or without dexamethasone for 1 h, then stimulated with 5 micrograms/ml lipopolysaccharide (LPS). Gene expression and production of IL-10 by human PBMCs were detected without stimulation and increased by LPS stimulation. Dexamethasone suppressed the gene expression and production of IL-10 by LPS-stimulated PBMCs in a dose-dependent manner by 41.6 and 61.1% at 10(-6) M, respectively. Also in monocytes, the gene expression and production of IL-10 were detected without stimulation, increased by LPS stimulation, and significantly suppressed by dexamethasone by 53.1 and 61.2% at 10(-6) M, respectively. This suppressive effect on IL-10 gene expression was not so potent compared with its effect on cytokines such as IL-5. The suppression of IL-10 production by glucocorticoid is suggested to be one of the important mechanisms by which glucocorticoids suppress allergic inflammation in the treatment of allergic diseases.

Blotting, Northern↗
PubMed1997

Patch-clamp characterization of secretory process in human basophils.

The effects of the intracellular Ca2+ concentration ([Ca2+]i) and a nonhydrolyzable guanosine triphosphate, guanosine 5'-o-(3-thiotriphosphate) (GTP-gamma-S), on secretion were studied by a patch-clamp technique in human basophils. When 10 microM Ca2+ were applied intracellularly, the granules dispersed rapidly, moved vigorously and fused to the cell membrane in 5 min. When the cells were exposed to 2 microM [Ca2+]i and 100 microM GTP-gamma-S, the granules dispersed gradually and granule fusion continued for 7-10 min. The plasma membrane conductance did not appreciably change with either 10 microM [Ca2+]i alone or 2 microM [Ca2+]i + 100 microM GTP-gamma-S. Intracellular application of Ca2+, 1-10 microM, caused a dose-dependent increase in cell membrane capacitance, which reflects granule membrane fusion, indicating exocytosis in a Ca2+ concentration-dependent manner. The addition of 100 microM GTP-gamma-S promoted an increase in the plasma membrane capacitance at concentrations from 0.1 to 2 microM [Ca2+]i and at 2 microM [Ca2+]i the increase was 4.4 times greater than that with 2 microM [Ca2+]i alone. These results indicate that certain G protein(s) promote Ca2+-dependent exocytosis in human basophils.

Basophils↗