Biomedical subjects

H Kai

Publications and source records attributed to H Kai.

At least 73 records · Page 4Linked to original sources

PubMed1997

[Bakumondo-to, a traditional herbal medicine, stimulates phosphatidylcholine secretion, through the synergistic cross-talk between different signal transduction systems in alveolar type II cells].

Traditional herbal medicines, Kampo medicines in Japan, are composed of various herbs with ubiquitous pharmacological activities. We previously found that Bakumondo-to stimulates phosphatidylcholine (PC) secretion from alveolar type II cells. To define the regulatory mechanisms involving in the Bakumondo-to-induced PC secretion, we investigated the effect of Bakumondo-to on signal transduction systems in alveolar type II cells, Bakumondo-to-induced PC secretion was completely inhibited by each of H-89, H-7 or BAPTA-AM, protein kinase A (PKA), protein kinase C (PKC) or intracellular Ca2+ inhibitor. In addition, Bakumondo-to increased cellular cyclic AMP content and Ca2+ content, too. These results suggested that the secretagogue effect of Bakumondo-to may be coupled to the synergistic cross-talk between cyclic AMP- and Ca(2+)-dependent system. To investigate if there is cross-talk between different signaling systems in type II cells, we examined the combined effects of various secretagogues on PC secretion. The combination of terbutaline and PMA potentiated stimulation of secretion, although the effects of terbutaline with A23187, or PMA with A23187 were additive. This synergism seemed to be mediated by Ca2+ influx, because this combination significantly increased cellular Ca2+ content. These findings suggested that there is synergistic cross-talk between PKA- and PKC dependent signaling system in alveolar type II cells, and that Bakumondo-to may stimulate PC secretion through this cross-talk.

Animals↗

PubMed1997

Dexamethasone increases beta 2-adrenoceptor-regulated phosphatidylcholine secretion in rat alveolar type II cells.

Insufficient production of pulmonary surfactant in alveolar type II cells is relevant to many lung diseases. To cure its deficiency, glucocorticoid is commonly used in clinical areas. In the present study, we investigated the effect of dexamethasone on the secretion of phosphatidylcholine, a major phospholipid of pulmonary surfactant, in a primary culture of rat alveolar type II cells. Dexamethasone had no effect on the basal secretion rate of phosphatidylcholine. Dexamethasone augmented both the phosphatidylcholine secretion and the cyclic AMP formation increased by terbutaline. Furthermore, dexamethasone increased the number of beta-adrenoceptors and mRNA expression of beta 2-adrenoceptors in type II cells. These findings indicate that dexamethasone increases pulmonary surfactant secretion through an enhancement of beta 2-adrenoceptor gene expression.

Adrenergic beta-Agonists↗

PubMed1997

Effects of xanthine derivatives on phosphatidylcholine secretion in rat type II pneumocytes in the presence of activated eosinophils.

We have previously reported that activated eosinophils enhanced the phosphatidylcholine (PC) secretion in type II pneumocytes. In this study, we have determined whether xanthine derivatives affect the PC secretion increased by activated eosinophils. Theophylline enhanced the increased PC secretion at 10(-5) M. 8-Phenyltheophylline dose-dependently enhanced the PC secretion. The enhanced secretion by either theophylline at 10(-5) M or 8-phenyltheophylline was suppressed by superoxide dismutase in combination with catalase. Pentoxifylline did not enhance the PC secretion increased by activated eosinophils, although it increased the PC secretion by itself. The PC secretion increased by theophylline at 10(-3) M or pentoxifylline was not suppressed by superoxide dismutase in combination with catalase. The present results suggest that xanthine derivatives increased the PC secretion in the co-culture of type II pneumocytes and activated eosinophils possibly through the inhibition of phosphodiesterases or the antagonism of adenosine receptors of the eosinophils.

Animals↗

PubMed1997

Effect of human neutrophil elastase on tracheal mucociliary transport in anesthetized quails.

We investigated the effect of human neutrophil elastase (HNE) on tracheal mucociliary transport in anesthetized quails. Topical application of HNE (30-300 microg/kg) to tracheal mucosa dose-dependently decreased mucociliary transport velocity (MCTV). The HNE (300 microg/kg)-induced decrease in MCTV was blocked by ONO-5046 x Na (sodium N-[2-[4-(2,2-dimethylpropionyloxy)phenyl-sulfonylamino]benzo yl]aminoacetate tetrahydrate) (3-30 mg/kg, i.m.), a specific neutrophil elastase inhibitor. Furthermore, we found that HNE increased DNA, fucose and protein contents of tracheal lavages, and the increases were also reverted by ONO-5046 Na. These results indicated that HNE decreased tracheal mucociliary transport, and the decrease may be, at least in part, ascribed to the deterioration of tracheal secretions.

Animals↗

PubMed1996

Transcriptional regulation of the lysozyme gene in airway gland serous cells.

Lysozyme is expressed in serous, but not mucous, cells of the tracheobronchial glands and thereby constitutes a marker of the serous cell lineage in these glands. To identify DNA regulatory elements and transcription factors mediating the commitment of progenitor cells to the serous cell lineage, we have characterized the regulatory activity and DNA-protein interactions of the 5'-flanking region of the bovine lysozyme gene lys 5a. Results obtained from these studies indicate that although approximately 94 bp of 5'flanking DNA are necessary for high level expression in transient transfection assays, an evolutionarily conserved promoter within 66 bp of the transcription start site is sufficient to confer serous cell-specific expression. Farther upstream, within 6.1 kb of the 5' flanking region, are 4 silencers. Analysis of the serous cell-specific lysozyme promoter by electrophoretic mobility shift assay (EMSA) revealed the presence of binding sites for 3 serous cell nuclear proteins, designated LSF1, LSF2 and LSF3. Binding of LSF2 and LSF3 was localized to a 20-mer subdomain (-50/-30) of the cell-specific promoter using binding competition assays. More accurate identification of the protein binding site(s) was achieved through the use of mutagenesis, which implicated the motif 5' AAGGAAT 3' (-46/-40) in both protein binding and serous cell-specific transcriptional activity. This motif has previously been identified as a binding site for ets protein transcription factors, suggesting that serous cell-specific regulation of lys 5a transcription is partly controlled by the binding of ets-like protein(s) to the motif 5'AGGAAGT3'.

Amino Acid Sequence↗

PubMed1996

Pyridine derivatives stimulate phosphatidylcholine secretion in primary cultures of rat type II pneumocytes.

We have examined the effects of pyridine derivatives on phosphatidylcholine secretion in primary cultures of rat type II pneumocytes. Of 12 pyridine derivatives, 4-aminopyridine, 4-dimethylaminopyridine and 4-pyrolidinopyridine had a stimulatory effect on phosphatidylcholine secretion, whereas other derivatives had little effect. The stimulatory effect of 4-aminopyridine was concentration- and time-dependent, and was inhibited by the acetoxymethyl ester of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (3 microM), an intracellular Ca2+ chelator. In addition, the stimulatory effect of 4-aminopyridine was suppressed by W-7(N-(6-aminohexyl)-5-chloro-1-napthalene-sulphonamide)(10 microM), a calmodulin inhibitor, and sphingosine (10 microM) and staurosporine (0-1 microM), protein kinase C inhibitors. These results indicate that several pyridine derivatives stimulate phosphatidylcholine secretion in type II pneumocytes.

4-Aminopyridine↗

PubMed1996

Dexamethasone suppresses mucus production and MUC-2 and MUC-5AC gene expression by NCI-H292 cells.

Excessive production of airway mucus is a characteristic feature of many chronic inflammatory lung diseases. Although current pharmacological approaches to excessive mucus production are limited, glucocorticoids appear to be the most effective among a few useful drugs. The exact evidence for the effectiveness of glucocorticoids on mucus production has not been fully elucidated to date. The purpose of this study is to clarify the effect of dexamethasone on mucus production and mucin gene expression in a human pulmonary mucoepidermoid carcinoma cell line (NCI-H292). NCI-H292 cells produced hyaluronidase-resistant high-molecular-weight glycoconjugates (HMWG), which elute in the void volume on Sepharose CL-4B column chromatography. Dexamethasone significantly suppressed the basal production of [3H]glucosamine-or [3H]serine-labeled HMWG in NCI-H292 cells. In Northern blot analysis, dexamethasone attenuated steady-state mRNA levels of MUC-2 and MUC-5AC mucin genes. These data indicate that dexamethasone suppresses the basal production of HMWG and decreases steady-state mRNA levels of mucin genes in airway mucus-producing cancer cells.

Carcinoma↗

PubMed1996

Effect of leukotriene D4 on tracheal mucociliary transport velocity in quails.

We investigated the effect of leukotriene D4 (LTD4) on tracheal mucociliary transport in quails. Topical application of LTD4 (0.2-2 ng) to tracheal mucosa dose-dependently increased mucociliary transport velocity (MCTV) in 5 or 10 min after application. Forty minutes after application of 2 ng of LTD4, MCTV was decreased to about 84% of that in the control group. Both the transient increase and the subsequent decrease induced by 2 ng of LTD4 were blocked by ONO-1078 (Pranlukast: 4-oxo-8-[4-(4-phenylbutoxy)-benzoylamino]-2-(tetrazol-5-yl)- 4H- 1-benzopyran) (0.03-3 mg/kg, i.m.), a specific leukotriene antagonist. These results suggest that LTD4 possesses a biphasic effect on tracheal mucociliary transport through leukotriene receptors.

Animals↗

PubMed1996

Prolonged exposure to agonist results in a reduction in the levels of the Gq/G11 alpha subunits in cultured vascular smooth muscle cells.

Recent studies have shown that G proteins are a potential regulatory site in the transmembrane signaling cascade. The aim of this study was to examine the effects of prolonged agonist exposure on expression of the Gq class of G protein alpha subunits (G alpha q/G alpha 11) in cultured rat vascular smooth muscle cells (VSMC). Treatment with 100 nM angiotensin II (Ang II) led to a substantial sustained down-regulation of cellular levels of immunologically detectable G alpha q/G alpha 11 by 50% within 6 hr. The effect of Ang II was dose dependent with an EC50 of 2 nM and was specifically blocked by the vascular type-1 Ang II receptor-specific antagonist losartan. The Ang II-induced reduction in cellular levels of G protein alpha subunits was specific for G alpha q/G alpha 11. The calcium ionophore ionomycin or activators of ubiquitous protein kinases (phorbol-12-myristate-13-acetate, forskolin, and 8-bromo-cGMP) did not mimic the effects of Ang II. However, [Arg8]vasopressin also induced a significant loss in cellular G alpha q/G alpha 11 levels. Ang II-induced G alpha q/G alpha 11 down-regulation was reversed by prevention of cellular receptor processing with phenylarsine oxide or chronic potassium depletion. The effects of Ang II on G alpha q/G alpha 11 levels were inhibited when protein kinase C activity was abolished. G alpha q mRNA levels were down-regulated by 30% after 4-hr incubation with Ang II, in part by transcriptional regulation. Although a short term vasopressin pretreatment had no effect on inositol-1,4,5-trisphosphate (IP3) generation in response to subsequent Ang II stimulation, a partial heterologous desensitization of the IP3 response was induced after a long term vasopressin pretreatment, which concurrently down-regulated cellular G alpha q/G alpha 11 levels. Homologous desensitization of IP3 generation on a second Ang II stimulation was observed after both a short and long term Ang II pretreatment. In conclusion, prolonged exposure to Ang II induces down-regulation of cellular G alpha q/G alpha 11 levels in intact VSMC. The effect of Ang II appears to be mediated by the signaling pathway sensitive to inhibition of receptor processing. The present study raises the possibility that agonist-induced G alpha q/G alpha 11 down-regulation participates in the mechanism of long term desensitization of the G alpha q/G alpha 11-mediated signaling system in VSMC.

Angiotensin II↗

PubMed1996

Activated eosinophils stimulate phosphatidylcholine secretion in primary culture of rat type II pneumocytes.

Activated eosinophils in airway epithelium are involved in the pathogenesis of many airway diseases. We examined whether activated eosinophils influence the secretion of phosphatidylcholine (PC), the predominant component of pulmonary surfactant, in primary culture of rat type II pneumocytes. The eosinophils (10(5) cells/ml) activated by opsonized zymosan (100 micrograms/ml) increased PC secretion from the type II pneumocytes. The increased PC secretion reduced in the presence of both superoxide dismutase (2 units/ml) and catalase (1000 units/ml). These results suggest that activated eosinophils stimulate the secretion of pulmonary surfactant partly through superoxide anions.

Animals↗

PubMed1995

Cytochrome b-558 alpha-subunit cloning and expression in rat aortic smooth muscle cells.

Recent studies have shown that the NADPH oxidase participates in the generation of superoxide anion in non-phagocytic cells. Here we report the isolation and nucleotide sequence of a cDNA for the cytochrome b-558 alpha-subunit of the NADPH oxidase in rat vascular smooth muscle cells (VSMCs). The coding region of the cDNA was 93% homologous to mouse and 81% to human in nucleotide sequence and 96% homologous to mouse and 89% to human in the deduced amino acid sequence. Our results provide a tool with which to explore the mechanism of superoxide anion generation in rat VSMCs and other non-phagocytic cells.

Amino Acid Sequence↗

PubMed1995

Contributing factors influencing type III open tibial fractures.

Ninety-five patients with severe open tibial fractures (96 fractures) were treated with nonoperative treatment alone (NO group, n = 16), immediate internal fixation (I group, n = 22), delayed internal fixation (D group, n = 34), or external fixation (EF group, n = 24). The D group was divided into a delayed internal fixation group following nonoperative treatment (D1 group, n = 14), and a delayed internal fixation group following external fixation (D2 group, n = 20). Using the classification system of Gustilo, there were 43 type IIIA, 42 type IIIB, and 11 type IIIC open tibial fractures. There were 17 deep infections (type IIIA, n = 3; IIIB, n = 12; IIIC, n = 2). The difference in the deep infection rate (DIR) between the type IIIA and type IIIB fractures was statistically significant (7.0% vs. 28.0%, p < 0.05). The DIRs in groups NO, I, D1, D2, and EF were 12.5, 27.3, 7.1, 35, and 4%, respectively. There was a significant difference in DIR between the D2 group and the EF group. The DIR in the D (D1 + D2) group and group I showed no significant difference. There was no relationship between the DIR and either Injury Severity Score or skin closure time. The authors of this study, therefore, do not feel there is an advantage to immediate internal fixation over delayed procedures for Gustilo type III open fractures of the tibia. However, careful attention must be given to the application of delayed internal fixation, especially intramedullary nailing, after external fixation.

Adolescent↗

PubMed1995

Impaired endothelium-dependent vasodilation of large epicardial and resistance coronary arteries in patients with essential hypertension. Different responses to acetylcholine and substance P.

Hypertensive patients have impaired endothelium-dependent coronary vasodilation evoked with acetylcholine. The aim of this study was to examine whether the impaired endothelium-dependent dilation of coronary arteries is related to a specific abnormality of the muscarinic receptor that mediates the effects of acetylcholine. Responses of the large epicardial and resistance coronary arteries were assessed in seven hypertensive patients (mean arterial pressure, 106 +/- 14 mm Hg) and seven control subjects (83 +/- 6 mm Hg, P < .01) during cardiac catheterization. To assess coronary endothelial function, we infused acetylcholine and substance P (endothelium-dependent agents that act on different receptors) and papaverine and nitrate (direct vascular smooth muscle dilators) into the left anterior descending coronary artery and determined coronary artery diameter by arteriography and coronary blood flow with an intracoronary Doppler catheter technique. In control subjects, 3 micrograms/min acetylcholine increased (P < .05) and 30 micrograms/min acetylcholine decreased (P < .05) arterial diameter, and in hypertensive patients, 1, 3, 10, and 30 micrograms/min acetylcholine decreased arterial diameter in a dose-dependent manner. Substance P at 3, 10, and 30 ng/min caused comparable increases in diameter in both groups. Increases in coronary blood flow with both acetylcholine and substance P were significantly (P < .01) blunted in hypertensive patients compared with control subjects. No significant differences were noted between the groups in the responses of large epicardial coronary artery diameter and coronary blood flow to papaverine and nitrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

PubMed1995

Improvement of coronary vasomotion with eicosapentaenoic acid does not inhibit acetylcholine-induced coronary vasospasm in patients with variant angina.

Impaired function of the endothelium may be a mechanism of the coronary vasospasm induced by acetylcholine. We examined whether purified eicosapentaenoic acid (EPA), a major component of fish oil, improves the coronary vasomotion in response to acetylcholine, and the effect of purified EPA on acetylcholine (ACh)-induced coronary vasospasm in 22 patients with variant angina. ACh was infused into the coronary artery both before and after 4 months of EPA treatment (EPA 1.8 g/day, n = 12). In the control group (n = 10) that did not receive EPA, the response of the coronary diameter to ACh did not change over time. In the EPA-treated group, the cholinergic response in non-spastic sites changed from vasoconstriction to vasodilation, while ACh-induced coronary vasospasm persisted at the spastic sites. Therefore, EPA treatment improved the coronary vasomotor responsiveness to ACh, but did not inhibit ACh-induced coronary vasospasm.

Acetylcholine↗

PubMed1995

Effects of xanthine derivatives on phosphatidylcholine secretion in primary culture of rat type II pneumocytes.

Xanthine derivatives, pentoxifylline, aminophylline, theophylline and chinoin-170, increased phosphatidylcholine secretion in a primary culture of rat type II pneumocytes. However, these xanthines alone had no effect on intracellular cAMP levels in type II pneumocytes. In contrast, terbutaline-induced secretion of phosphatidylcholine was augmented by these xanthines, and the augmentation depended on the increase of cAMP levels. These results suggest that the xanthines induce phosphatidylcholine secretion possibly through cAMP-dependent and cAMP-independent pathways in the primary culture of rat type II pneumocytes.

Aminophylline↗

PubMed1995

Changes in beta 1- and beta 2-adrenoceptor mRNA levels in alveolar type II cells during cultivation.

Alveolar type II cells, the progenitor of type I epithelial cells, synthesize and secrete pulmonary surfactant. In this study, we determined the levels of mRNA for beta 1- and beta 2-adrenoceptor in cultured type II cells using a quantitative RNase protection assay. The mRNA levels for beta 1- and beta 2-adrenoceptors in the freshly isolated cells were 0.51 +/- 0.07 and 1.92 +/- 0.19 amol/microgram total cellular RNA, respectively. In the cells cultured for over 2 days, only beta 1-adrenoceptor mRNA level was remarkably reduced. These results suggest that each mRNA expression may be separately regulated in cultured alveolar type II cells.

Animals↗

PubMed1995

Substance P stimulates the loss of cell-associated high molecular weight glycoconjugates from cultured hamster tracheal epithelial cells through polymorphonuclear leucocytes activation.

Abnormal and excessive mucus secretion is a characteristic feature of many chronic inflammatory lung diseases accompanied by the influx of polymorphonuclear leucocytes (PMNs) into the airway and the release of substance P from the peripheral endings of primary sensory neurons. We examined whether PMNs activated by substance P (10 microM) can affect the secretion of high-molecular-weight glycoconjugates (HMWG), which is used as a marker of mucus, from cultured hamster tracheal epithelial cells. We measured both the released and the cell-associated HMWG. Substance P-activated PMNs (10(6) cells/ml) reduced the amount of cell-associated HMWG to 76% of the control level, but did not affect the amount of the released HMWG. The reduction of the amount of cell-associated HMWG was inhibited by ONO-5046, a specific elastase inhibitor. In addition, the HMWG was digested by the activated PMNs. These findings suggested that substance P stimulates the loss of the cell-associated HMWG and degrades the released HMWG from cultured hamster tracheal epithelial cells through PMNs activation.

Animals↗

PubMed1994

Molecular cloning of the amino-terminal region of a rat MUC 2 mucin gene homologue. Evidence for expression in both intestine and airway.

To obtain cDNAs for analysis of mucin gene transcription in rat models of human disease, we screened a rat intestinal cDNA library in lambda ZAPII using an upstream non-tandem repeat cDNA fragment of the human MUC 2 gene (Gum, J., Hicks, J., Toribara, N., Rothe, E., Lagace, R., and Y., K. (1992) J. Biol. Chem. 267, 21375-21383). Three cDNAs, 1-1, 8-1, and 21-1, were isolated. A translation start site was found in cDNA 21-1. Combined nucleotide sequence for the three cDNAs contained an open reading frame spanning 4546 base pairs. This amino-terminal sequence contains a non-tandem repeat domain enriched in cysteine (1391 residues) followed by an irregular tandem repeat domain (122 residues). Identity with the human gene is about 80% in the non-tandem repeat domain and about 38% in the irregular tandem repeat domain. Primer extension and S1 nuclease protection analysis indicate a transcription start site at 28 base pairs upstream of translation initiation. Northern analysis showed expression of cognate RNA in the intestine and airway but not heart and spleen. The cDNAs have been used to isolate the gene promoter, the structure of which should yield clues to the regulation of mucin expression in rat models of human disease.

Amino Acid Sequence↗