Biomedical subjects

T Takaishi

Publications and source records attributed to T Takaishi.

At least 37 records · Page 2Linked to original sources

PubMed1996

Effects of endothelial cells on activity of staphylokinase.

Staphylokinase (SAK), produced by Staphylococcus aureus, induces fibrinolytic activity in circulation without systemic fibrinolytic activation. Since the effect of blood vessels on the activity of SAK has not yet been clarified, plasminogen activator (PA) activity of SAK in the presence or absence of endothelial cells was analyzed. The endothelial cells used in this experiment were of a cloned established cell line (TKM-33). In the expression of PA activity by SAK or streptokinase (SK), the kinetic constants revealed as Vmax/km were increased about 1.5-fold in the presence of endothelial cells. Furthermore, an initial lag phase which was observed during the plasminogen activation by SAK was markedly shortened in the presence of endothelial cells. In the case of SK, an initial lag phase was not observed in the absence or presence of endothelial cells. Although PA activity of SAK was inhibited by alpha 2-antiplasmin (alpha 2-AP), the inhibitory effect of alpha 2-AP in the presence of endothelial cells was weaker than in the absence of endothelial cells. The cyanogen bromide digested fibrinogen fragment-2 (FCB-2) distinctly enhanced the PA activity of SAK in the absence and the presence of endothelial cells. However, alpha 2-AP and FCB-2 did not cause a significant alteration of PA activity of SK even in the absence or presence of endothelial cells. These findings suggest that PA activity of SAK is enhanced by endothelial cells, but inhibited by alpha 2-AP. Moreover, PA activity of SAK is further enhanced by fibrin clot in the presence of endothelial cells.

Cell Line↗

PubMed1996

Optimal pedaling rate estimated from neuromuscular fatigue for cyclists.

This study was designed to examine the optimal pedaling rate for pedaling exercise at a given work intensity for cyclists. Six college-aged cyclists each performed six sessions of heavy pedaling exercise at individually selected work rates based on their aerobic capacity. The optimal pedaling rate was evaluated on the basis of minimal neuromuscular fatigue as evidenced by the integrated electromyogram (iEMG) slope defined by the changes in iEMG as a function of time. The means of the iEMG slope demonstrated a quadratic curve versus pedaling rate. The mean values at 80 rpm (0.53 (SD 0.20) microV.min-1) and 90 rpm (0.67 (SD 0.23) microV.min-1) were significantly smaller than those values at any other pedaling rate. On the other hand, the mean value of oxygen uptake (VO2) expressed as a percent of the subject's maximal VO2 (% VO2max) at each pedaling rate also showed a quadratic curve with minimal values at about 60 or 70 rpm. VO2 at 70 rpm (84.0 (SD 5.0) % VO2max) was significantly smaller than those values at 80 rpm (86.3 (SD 3.5) % VO2max), 90 rpm (87.4 (SD 3.8) % VO2max), and 100 rpm (90.1 (SD 3.8) % VO2max). These data strongly suggest that the optimal pedaling rate estimated from neuromuscular fatigue in working muscles is not coincident with the pedaling rate at which the smallest VO2 was obtained, but with the preferred pedaling rate of the subjects. Our findings also suggest that the reason that cyclists prefer a higher pedaling rate is closely related to the development of neuromuscular fatigue in the working muscles.

Adult↗

PubMed1996

Pharmacologic study of basophil histamine release induced by monocyte chemotactic protein-1 with kinase inhibitors.

Monocyte chemotactic protein-1 (MCP-1)/monocyte chemotactic activating factor has a potent histamine-releasing activity for basophils and is a major component of IgE-independent histamine-releasing factors (HRF). In this study, we examined the effect of a panel of kinase inhibitors on MCP-1-induced histamine release from human basophils to characterize the signaling pathway used by this chemokine. Genistein (3 micrograms/ml), an inhibitor of tyrosine kinase, inhibited MCP-1-induced histamine release by 44%. Wortmannin is a specific inhibitor of phosphatidylinositol 3 kinase (PI-3 kinase). It blocked MCP-1-induced histamine release with an IC50 of 3.3 x 10(-8) M indicating a role of PI-3 kinase in this reaction. KT5926, an inhibitor of myosin light chain kinase, also inhibited histamine release in response to MCP-1 with an IC50 of 10(-6) M. Staurosporine, a potent inhibitor of protein kinase C, although being not specific, augmented MCP-1-induced histamine release by 31.9% at 10(-6) M. These results indicate the possible involvement of a series of kinases, including PI-3 kinase, in the signal transduction pathway used by MCP-1.

Alkaloids↗

PubMed1996

Airway basophil and mast cell density in patients with bronchial asthma: relationship to bronchial hyperresponsiveness.

We investigated the role of basophils and mast cells in the pathogenesis of bronchial asthma. Eight asthmatics (6 atopic, 2 nonatopic) and 6 control subjects were enrolled in this study. Bronchial responsiveness to acetylcholine (PC20ACh) was measured in asthmatics and endobronchial biopsy from right upper lobe bronchus was performed on the same day. Basophils and mast cells in the airways were identified by immunohistochemistry using a monoclonal antibody against tryptase and anti-IgE. The number of basophils of asthmatics was 52.2 +/- 12.5/mm(2). In contrast, no basophils were found in the airways of control subjects. There was a significant increase of number of mast cells in the asthma group compared to the control group (168.6 +/- 32.6 vs. 22.3 +/- 6.1, p<0.01). There was an inverse correlation between airway basophil and mast cell numbers and PC20ACh (r=-0.82, r=0.72, p<0.05). These findings suggest a possible role for basophils and mast cells in the pathophysiology of asthma.

Acetylcholine↗

PubMed1996

Effect of heat shock on the expression of urokinase-type plasminogen activator receptor in human umbilical vein endothelial cells.

We investigated the effect of heat shock on the fibrinolytic potential of human umbilical vein endothelial cells (HUVECs) in culture. When cultured at 43 degrees C, the mRNA for heat shock protein 70 (HSP70) was dramatically induced within 120 min with a maximal induction of more than 90-fold compared with that in HUVECs cultured at 37 degrees C. The level of urokinase-type plasminogen activator (u-PA) receptor (u-PAR) mRNA increased up to 2.2-fold in response to heat shock, which was associated with the increased u-PA binding and cell-surface u-PA activity determined by adding exogenous u-PA to acid-treated HUVECs. The increased u-PAR mRNA returned to normal level when HUVECs were further incubated at 37 degrees C for 180 min, and this decline was not affected in the presence of actinomycin D. Though the secreted antigens for tissue-type plasminogen activator (t-PA) and type 1 plasminogen activator inhibitor (PAI-1) in the conditioned medium (CM) of HUVECs were simultaneously increased at 43 degrees C during this period, the increase in the levels of t-PA (about 26.6-fold at 120 min) was greater than that of PAI-1 (1.8-fold at 120 min). The fibrinolytic activity of CM obtained from HUVECs at 43 degrees C was significantly enhanced up to 3-fold, indicating that heat shock induced hyperfibrinolytic states in HUVECs. The secretion of u-PA into CM was also enhanced by heat shock. These results suggested that human endothelial cells respond to hyperthermia by inducing HSP70 followed by hyperfibrinolytic states with the enhanced expression of u-PAR as well as that of t-PA and u-PA.

Base Sequence↗

PubMed1995

Pharmacological study of stem-cell-factor-induced mast cell histamine release with kinase inhibitors.

Stem cell factor (SCF) is a ligand for c-kit receptor and has a critical role in the development of mast cells. In this study, we investigated the effect of a panel of kinase inhibitors on SCF-induced histamine release from rat peritoneal mast cells. Genistein, an inhibitor of tyrosine kinases, inhibited SCF-induced histamine release with IC50 of 1.6 x 10(-5) M. Wortmannin, an inhibitor of phosphatidylinositol 3'-kinase (PI3 kinase), inhibited histamine release stimulated with SCF dose-dependently with IC50 of 4 x 10(-9) M. KT5926, an inhibitor of myosin light chain (MLC) kinase, reduced histamine release with IC50 of 1.8 x 10(-7) M. Staurosporine, an inhibitor of protein kinases, also inhibited SCF-induced histamine release with IC50 of 6.5 x 10(-8) M. These results show the early involvement of tyrosine kinase and PI3 kinase and the possible role of MLC kinase in the late secretory phase in the signaling pathway used by SCF.

Alkaloids↗

PubMed1995

Chemotactic agonists induce cytokine generation in eosinophils.

Recent studies have shown that eosinophils are capable of generating and releasing cytokines, providing a novel biologic aspect of eosinophils for regulating allergic inflammation by an autocrine or paracrine mechanism. Eosinophils synthesize various cytokines; however, the physiologic stimuli that trigger eosinophils to generate cytokines have not been fully elucidated. We examined the effect of chemotactic agonists on eosinophil cytokine generation by employing the determination of IL-8 as the main parameter. Both C5a and FMLP stimulated eosinophils to release IL-8, whereas platelet-activating factor and C-C chemokines did not exert any significant effects. On a molar basis, C5a was two orders of magnitude more potent than FMLP. The generation of IL-8 by chemoattractants was absolutely dependent on the presence of cytochalasin B. Pertussis toxin completely attenuated C5a- and FMLP-induced IL-8 production, indicating the involvement of pertussis toxin-sensitive G-proteins in the signal-transduction process leading to these responses. Experiments of in situ hybridization and PCR amplification revealed that both C5a and FMLP promoted eosinophil IL-8 production through transcriptional gene activation. Pyrrolidine dithiocarbamate completely abrogated chemoattractant-induced IL-8 production, indicating the involvement of NF-kappa B in the cytoplasmic/nuclear signal-transduction process. Furthermore, chemoattractant-induced cytokine production was not limited to IL-8; C5a and FMLP but not platelet-activating factor induced significant secretion of granulocyte-macrophage-CSF from eosinophils. These results indicate that C5a and FMLP stimulate eosinophils to elaborate cytokines, which could be an important mechanism in the regulation of allergic inflammation.

Base Sequence↗

PubMed1995

Cholecystokinin-B/gastrin receptor: a novel molecular probe for human small cell lung cancer.

The brain-gut hormones, gastrin and cholecystokinin, have a trophic effect on the gastrointestinal mucosa in vivo and promote the growth of several neoplastic cell lines. In this study, cholecystokinin-B/gastrin receptor has been demonstrated to provide a novel molecular marker for the diagnosis of small cell lung cancer by using biopsy specimens. Physiological expression of the receptor mRNA is detectable in particular areas of the human brain, stomach, and pancreas but not in the lung. The receptor mRNA was detected selectively in all small cell lung cancer (10 cases) with a RT-PCR assay. By contrast, it was detectable in only 1 of 13 squamous cell carcinomas or 21 adenocarcinomas of the lung. Thus, the cholecystokinin-B/gastrin receptor could be an attractive therapeutic target for small cell lung cancer.

Adenocarcinoma↗

PubMed1995

Fibrinolytic activity in liver tissues of stroke-prone spontaneously hypertensive rats.

1. Plasminogen activator activity was detected in the extract solution of the liver tissues of both stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats by the synthetic substrate assay. 2. The total PA activity in the liver extract of WKY (26.8 +/- 8.3 i.u.) was about 1.5-fold higher than that of SHRSP (18.5 +/- 4.1 i.u., n = 8, P < 0.005). 3. The enzymography of the liver extract revealed three lytic bands with a molecular weight of 67 kDa, 44 kDa and 38 kDa. 4. The inhibitor activity of the liver extract was detected by the reverse fibrin autography method with one lytic resistance band at 70 kDa. 5. Thus, fibrinolytic components exist in the liver tissue of both strains of rats, but their contribution to the stroke requires further study.

Amino Acid Sequence↗

PubMed1995

Induction of eosinophil cytokine generation by chemoattractants.

Recent studies have shown that eosinophils are capable of generating and releasing cytokines, illustrating a novel biologic aspect of eosinophils in regulating allergic inflammation by either autocrine or paracrine mechanisms. The effect of chemotactic agonists on eosinophil cytokine generation was examined by determination of interleukin-8 (IL-8) as a main parameter. Both complement C5a and N-formyl-methionyl-leucyl-phenylalanine (FMLP) stimulated eosinophils to release IL-8, but platelet activating factor (PAF) did not exert any significant effects. The generation of IL-8 by chemoattractants was absolutely dependent on the presence of cytochalasin B. Pertussis toxin completely attenuated C5a- and FMLP-induced IL-8 production, indicating the involvement of pertussis toxin-sensitive G proteins in the signal transduction process. In situ hybridization showed that both C5a and FMLP promoted eosinophil IL-8 production via transcriptional gene activation. Furthermore, C5a and FMLP, but not PAF, induced significant secretion of granulocyte-macrophage colony-stimulating factor from eosinophils. These results indicate that C5a and FMLP stimulate eosinophils to elaborate cytokines, which could be an important mechanism in the regulation of allergic inflammation.

Actin Cytoskeleton↗

PubMed1995

[A case in which bronchorrhea was alleviated by oral erythromycin and inhalation of beclomethasone and furosemide].

A 55-year-old woman with bronchorrhea and bronchial asthma was admitted to our hospital in June, 1992. On admission, she was producing a large volume of sputum (200 ml) each day. The volume decreased with oral administration of erythromycin and inhalation of beclomethasone. Next, inhalation of furosemide was added to the regimen, which lead to symptomatic improvement in mucus clearance, although the sputum increased in volume. The concentrations of albumin, fucose, sialic acid, and phosphatidylcholine in the sputum changed with these treatments, as did the lecithin/sphingomyelin ratio. These observations suggest that these drugs affect not only the quantity but also the quality of sputum.

Administration, Inhalation↗

PubMed1994

Lipopolysaccharide primes human basophils for enhanced mediator release: requirement for plasma co-factor and CD14.

Lipopolysaccharide (LPS) is known to enhance IgE-mediated basophil degranulation. Recently, the complex of LPS and plasma LPS-binding protein(LBP) has been shown to induce secretory response via CD14 in monocytes and neutrophils. In the current study, we observed that the sensitivity to LPS of basophils was increased to 100-fold by co-incubation with plasma. LPS promptly completed its effect and amplified degranulation by stimuli bypassing IgE-receptors. Treatment with anti-CD14 completely abolished the priming effect of LPS. These results indicate that the priming effect of LPS on basophil mediator release is mediated via CD14, and that plasma co-factor, possibly identical to LBP, potentiates this reaction.

Acute-Phase Proteins↗

PubMed1994

Neuromuscular fatigue during prolonged pedalling exercise at different pedalling rates.

The purpose of this study was to estimate the differences in neuromuscular fatigue among prolonged pedalling exercises performed at different pedalling rates at a given exercise intensity. The integrated electromyogram (iEMG) slope defined by the changes in iEMG as a function of time during exercise was adopted as the measurement for estimating neuromuscular fatigue. The results of this experiment showed that the relationship between pedalling rate and the means of the iEMG slopes for eight subjects was a quadratic curve and the mean value at 70 rpm [1.56 (SD 0.65) microV.min-1] was significantly smaller (P < 0.01) than that at 50 and 60 rpm [2.25 (SD 0.54), and 2.22 (SD 0.68), respectively]. On the other hand, the mean value of oxygen consumption obtained simultaneously showed a tendency to increase linearly with the increase in pedalling rate, and the values at 70 and 80 rpm were significantly higher than those at 40 and 50 rpm. In conclusion, it was demonstrated that the degree of neuromuscular fatigue estimated by the iEMG changes for five periods of prolonged pedalling exercise at a given exercise intensity was different among the different pedalling rates, and that the pedalling rate at which minimal neuromuscular fatigue was obtained was not coincident with the rate at which the minimal oxygen consumption was obtained, but was coincident with the rate which most subjects preferred. These findings would suggest that the reason why most people prefer a relative higher pedalling rate, even though higher oxygen consumption is required, is closely related to the development of neuromuscular fatigue in the working muscles.

Adult↗

PubMed1994

Effect of cytokines on mediator release from human dispersed lung mast cells.

To evaluate the contribution of human lung mast cells (HLMC) to allergic inflammation, we investigated whether or not cytokines, including stem-cell factor (SCF), monocyte chemotactic and activating factor (MCAF), and RANTES, activate HLMC. SCF induced histamine release from dispersed HLMC in a dose-dependent fashion (P < 0.01). The release was 7.8 +/- 1.0% at 500 ng/ml SCF (n = 9). This response was also observed in chopped lung tissue. HLMC from which surface IgE molecules had been removed by treatment with lactic acid responded to SCF, while these cells lost their response to anti-IgE. The process was relatively rapid and reached a maximum in 5 min. This response required extracellular calcium, and it was observed at 37 degrees C, but not at 4 degrees C or 20 degrees. A brief preincubation (10 min) with lower concentrations of SCF, which were ineffective in releasing histamine, enhanced anti-IgE-induced histamine release (P < 0.05), while its enhancing effect was lost by the longer preincubation (30 min). SCF did not prime basophils to enhance stimulated-histamine release. Interleukin (IL)-1 alpha, IL-1 beta, IL-3, IL-4, IL-5, granulocyte/macrophage-colony stimulating factor (GM-CSF), MCAF, and RANTES neither induced histamine release nor enhanced the release stimulated by anti-IgE after a 10- or 30-min preincubation. The combination of IL-3 and IL-4 showed no effect on histamine release from HLMC. Leukotriene (LT)C4/D4/E4 production by SCF was negligible, as compared with anti-IgE-induced LT production.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokines↗

PubMed1994

Dexamethasone inhibits basophil migration.

Glucocorticoids have been shown to inhibit the local accumulation of basophils during the allergen-induced late-phase reaction (LPR). Since migration is an essential step in the recruitment of basophils from the circulation, we examined whether the widely used glucocorticoid, dexamethasone (DEX), directly acts on basophils to inhibit the migration caused by C5a, interleukin (IL)-3, and IL-8. When purified basophils were preincubated with various concentrations of DEX, a dose-dependent inhibition was observed; DEX at concentrations as low as 1 nM reduced the number of migrated basophils by 30-40%; at higher concentrations, it showed a slightly stronger inhibitory effect. There was no significant difference in the effect of DEX on the migration caused by the three chemoattractants. The action of DEX took place rapidly; apparent inhibition was observed even when migration was initiated without preincubation. Although the inhibitory effect of this agent was not reversed when DEX was removed by washing, the inhibition was not mediated by the toxicity as measured by the trypan-blue exclusion test. These results indicate that the in vivo blocking effect of glucocorticoids on basophil accumulation during LPR is mediated in part by direct action to inhibit the migration of basophils.

Basophils↗

PubMed1994

Ventilatory responses at the onset of passive movement and voluntary exercise with arms and legs.

This study was undertaken to elucidate whether phase I appeared at the onset of voluntary and passive arm movements and to compare these results with those of similar leg movements. Instead of the conventional cranking exercise, seven male subjects performed alternately flexion-relaxation of both arms, extension-relaxation of both legs, and combined arm and leg exercise at the rate of about 60 min-1 for four breaths in a sitting position. Similar movements were accomplished passively by the experimenters. In all experiments, minute ventilation increased rapidly within the first breath after the onset of exercise. The difference of ventilation (delta value) between the mean of the first two breaths at the onset of voluntary exercise and that of five breaths during rest was significantly (P < 0.05) greater in arm (7.75 l min-1) than in leg (5.19 l min-1). Passive movement showed a similar tendency. Arm delta ventilation correlated highly (r = 0.74-0.91) with leg delta ventilation and the slope of the regression lines was about 1.2. Heart rate increased abruptly while cardiac output did not always increase rapidly at the onset of locomotion. Oxygen uptake in the voluntary leg exercise continued for 3 min was slightly but nonsignificantly higher than in the arm exercise, indicating the equality of the exercise intensity. In conclusion, ventilatory responses at the onset of the arm exercise are larger than those of the leg in both voluntary and passive conditions regardless of the muscle mass, suggesting the different neurogenic mechanism between arm and leg.

Adult↗

PubMed1994

TGF-beta-induced macrophage colony-stimulating factor gene expression in various mesenchymal cell lines.

We report here that transforming growth factor-beta (TGF-beta) can increase the expression level of macrophage colony-stimulating factor (M-CSF) mRNA in a variety of mesenchymal cell lines derived from osteoblasts, bone marrow stromal cells, fibroblasts, and myoblasts. The M-CSF activity in the conditioned medium of mouse osteoblast-like MC3T3-E1 cells was increased by TGF-beta as well as interleukin-1 (IL-1) treatment. The increase of M-CSF mRNA expression was observed as early as 2 h after TGF-beta or IL-1 addition and was superinduced by cycloheximide treatment. Nuclear run-off assays revealed that the increase in M-CSF mRNA by TGF-beta as well as IL-1 occurred, at least in part, at the transcriptional level. Platelet-derived growth factor (PDGF) also enhanced the M-CSF production in MC3T3-E1 cells. Furthermore, TGF-beta and IL-1 distinctly induced both PDGF-A and PDGF-B chain mRNA in MC3T3-E1 with different time courses. Our present studies suggest that PDGF autocrine loop-dependent and loop-independent pathways could modulate the M-CSF production stimulated by TGF-beta or IL-1 and account for the complexity of the cytokine network involving M-CSF in vivo under various physiological and pathological conditions.

Animals↗

PubMed1994

Retinoic acid differentially affects platelet-derived growth factor and epidermal growth factor-regulated cell growth of mouse osteoblast-like cells.

Retinoic acid (RA) plays an important role in the control of cell growth and differentiation. To elucidate the effects of RA for osteoblasts, we examined here the responsiveness of normal osteoblast-like MC3T3-E1 cells treated with RA for two growth factors, platelet-derived growth factor (PDGF) and epidermal growth factor (EGF). The transcripts of alpha- and gamma-RA receptors were constitutively expressed in MC3T3-E1 cells, and the expression of the beta-RA receptor mRNA was induced by RA. The PDGF-induced mitogenicity of MC3T3-E1 cells was significantly enhanced by 1 microM RA pretreatment, whereas the EGF-induced mitogenicity was suppressed by the same treatment. The expression of both alpha- and beta-PDGF receptor gene products detected by RNA blot and immunoblot analyses was significantly increased by RA. The increased expression of PDGF receptors was accompanied by the augmentation of PDGF-induced receptor autophosphorylation following the enhancement of inositol phosphate hydrolysis. In contrast, EGF-induced receptor autophosphorylation was suppressed in RA-treated cells, whereas the expression level of EGF receptor was not affected. These findings demonstrate that RA could control the cell growth of osteoblast-like MC3T3-E1 cells not only by regulating the gene expression of growth factor receptors, but also by modulating the ligand-induced receptor autophosphorylation.

Animals↗