Search PubMed⌕ Search

Biomedical subjects

K Konno

Publications and source records attributed to K Konno.

At least 145 records · Page 8Linked to original sources
PubMed1995

Effects of macrolide antibiotics on neurally mediated contraction of human isolated bronchus.

BACKGROUND: Long-term administration of macrolide antibiotic substances is an alternative therapy used in the treatment of asthma and airway hyperresponsiveness, but neither its mechanism of action nor whether this substance exerts an immediate action in the airways is known. METHODS: Contractile responses of human isolated bronchial strips to electrical field stimulation (EFS) and acetylcholine were assessed under isometric conditions in the absence and presence of erythromycin, roxithromycin, or clarithromycin. RESULTS: Incubation of tissues with erythromycin (3 x 10(-5) mol/L) attenuated the contractile responses to EFS so that the stimulus frequency required to produce 50% of the maximal contraction increased from 4.1 +/- 0.5 to 10.1 +/- 0.7 Hz (mean +/- SE; p < 0.001). In contrast, contractile responses to acetylcholine were not changed. Erythromycin reduced the EFS-induced contraction in a concentration-dependent fashion; the maximal decrease from the baseline response was 92.8% +/- 3.6% (p < 0.001). This inhibitory effect was not altered by propranolol, indomethacin, ouabain, charybdotoxin, or mechanical removal of the epithelium. Roxithromycin and clarithromycin likewise inhibited neurally mediated contraction. CONCLUSIONS: These results suggest that macrolides may inhibit cholinergic neuroeffector transmission in the human airway smooth muscle, probably by reducing exocytotic release of acetylcholine from the nerve terminals.

Acetylcholine↗
PubMed1995

[Effect of ciprofloxacin on contractile responses of canine airway smooth muscle].

To elucidate whether the new quinolone ciprofloxacin affects cholinergic neuto-effector transmission in the airway, we studied canine isolated bronchial segments under isometric conditions in vitro. Intrapulmonary lobar or segmental bronchi were suspended in the organ chambers filled with Krebs-Henseleit solution, and the isometric tension was continuously recorded by a force-displacement transducer. Addition of ciprofloxacin (2 x 10(-3) M) attenuated the contractile responses to electrical field stimulation (EFS), so that the stimulus frequency required to produce a half-maximal contraction (ES50) increased from 1.2 +/- 0.2 to 1.5 +/- 0.2 Hz (p < 0.05), whereas it was without effect on those to exogenously administered acetylcholine. The decrease in the EFS-induced contraction produced by ciprofloxacin was concentration-dependent and was not influenced by propranolol or tetraethylammonium, but partially inhibited by ouabain. These results suggest that ciprofloxacin may inhibit cholinergic neuro-effector transmission in the airway smooth muscle by inhibiting the exocytotic release of acetylcholine, probably involving the stimulation of Na(+)-K(+)-ATPase and concomitant repolarization/hyperpolarization of cholinergic nerve terminals.

Animals↗
PubMed1995

Potent and specific inhibition of human immunodeficiency virus type 1 replication by 4-(2,6-dichlorophenyl)-1,2,5-thiadiazol-3-Y1 N,N-dialkylcarbamate derivatives.

4-(2,6-Dichlorophenyl)-1,2,5-thiadiazol-3-yl N,N-dialkylcarbamate (TDA) derivatives were found to be highly potent and specific inhibitors of human immunodeficiency virus type 1 (HIV-1) replication in a variety of cell cultures. The most potent congener of TDA derivatives, RD4-2024, inhibited HIV-1 replication by 50% at concentrations of 12.5 and 4.8 nM in MT-4 cells and peripheral blood mononuclear cells, respectively. These concentrations were more than 2,000- and 30,000-fold lower than its 50% cytotoxic concentrations, respectively. Although the TDA derivatives were active against 3'-azido-3'-deoxythymidine-resistant HIV-1, no antiviral activities were observed against HIV-2 and nonnucleoside reverse transcriptase inhibitor-resistant mutants of HIV-1. The TDA derivatives inhibited recombinant HIV-1 reverse transcriptase activity, depending on the template-primer used for the assay. However, they did not interact with HIV-2 reverse transcriptase. Thus, the TDA derivatives belong to the family of nonnucleoside reverse transcriptase inhibitors. Because of their potent anti-HIV-1 activities in vitro and their low levels of toxicity in mice, the TDA derivatives deserve further evaluation as candidate drugs for the treatment of patients with AIDS.

Antiviral Agents↗
PubMed1995

Erythromycin shortens neutrophil survival by accelerating apoptosis.

Erythromycin is reported to have an anti-inflammatory action, which may account for its clinical effectiveness in the treatment of chronic inflammatory diseases such as diffuse panbronchiolitis. To evaluate the anti-inflammatory action of erythromycin, we examined the survival of isolated neutrophils with and without erythromycin. Erythromycin shortened neutrophil survival in a dose-dependent fashion, with a maximum effect at 10 micrograms/ml [corrected] and above. Survival at 24 h was 63.4% in medium with 10 micrograms of erythromycin per ml compared with 82.7% in control medium (P < 0.01). This shortening of survival was brought about by acceleration of apoptosis, as evidenced by transmission electron microscopy. In a manner similar to that of erythromycin, other macrolide antibiotics, i.e., clarithromycin, roxithromycin, and midecamycin, also shortened neutrophil survival, but neither the beta-lactams ampicillin and cefazolin nor the aminoglycoside gentamicin affected their survival. Erythromycin increased intracellular levels of cyclic AMP (cAMP) to 150% of control levels in neutrophils. Forskolin, rolipram, and dibutyryl-cAMP, which are known to increase intracellular cAMP levels, also shortened neutrophil survival. H-89, an inhibitor of cAMP-dependent protein kinase A, partially blocked the survival-shortening effect of erythromycin. Our findings suggest that erythromycin shortens neutrophil survival at least in part through elevation of intracellular cAMP levels.

Apoptosis↗
PubMed1995

Effect of clarithromycin on sputum production and its rheological properties in chronic respiratory tract infections.

Macrolide antibiotics possess a variety of actions other than antimicrobial activities. To determine the effects of long-term administration of clarithromycin (CAM) on the amount and physical properties of sputum in patients with clinical conditions associated with excessive airway secretions, we conducted the present study in a parallel, double-blind, placebo-controlled fashion. Patients were divided into two groups: the first group (n = 16) received CAM (100 mg, twice a day) for 8 weeks, and the second group (n = 15) received placebo. In evaluating airway secretion, the daily amount of expectorated sputum, solid composition, viscoelastic properties (including elastic modulus and dynamic viscosity), and sputum microbiology were assessed. CAM decreased sputum production from 51 +/- 6 to 24 +/- 3 g/day after treatment, whereas placebo had no effect. The bacterial density and sputum flora were unaltered. In the group receiving CAM, the percent solid composition and elastic modulus increased from 2.44% +/- 0.29% to 3.01% +/- 0.20% and 66 +/- 7 to 87 +/- 8 dyne/cm2 (P < 0.05), respectively, but the dynamic viscosity remained unchanged. These results suggest that long-term treatment with CAM reduces the amount of sputum production, probably by inhibiting airway secretions, and increases sputum elasticity.

Adult↗
PubMed1995

Role of NO generation in beta-adrenoceptor-mediated stimulation of rabbit airway ciliary motility.

To determine possible contribution of nitric oxide (NO) to the stimulatory action of beta-adrenoceptor agonist on ciliary motility, we measured ciliary beat frequency (CBF) of rabbit cultured tracheal epithelial cells by photoelectric method and NO release by specific amperometric sensors for this molecule in vitro. Salbutamol increased CBF, an effect that was potentiated by superoxide dismutase. Pretreatment of cells with NG-nitro-L-arginine methyl ester (L-NAME) attenuated the salbutamol-induced increase in CBF, causing a rightward displacement of the concentration-response curve by 2-2.5 log units, whereas NG-nitro-D-arginine methyl ester had no effect. The inhibitory effect of L-NAME was reversed by L-arginine but not by D-arginine. Immersion of the NO-selective electrode in the medium containing epithelial cells detected baseline current of 4.6-14.5 pA, which was abolished by L-NAME. Salbutamol dose-dependently increased the concentration of NO in the medium, the maximal increase being 56.2 +/- 5.3 nM (mean +/- SE; P < 0.001). These results suggest that NO is spontaneously released by airway epithelium and that the enhanced release of this molecule may play a role in the beta-adrenoceptor-mediated stimulation of ciliary motility.

Albuterol↗
PubMed1995

Effect of indomethacin on lung development in postnatal rats: possible role of prostaglandin in alveolar formation.

We administered 1.3 mg ip of indomethacin, a prostaglandin synthetase inhibitor, per 100 g body wt to male rat pups daily on postnatal days 4-13 and examined their lungs on day 14. Indomethacin administration produced abnormal lung structure with diminished alveolar air, increased alveolar duct air, increased mean linear intercept (gas-exchanging wall distance), diminished gas-exchanging surface area and surface-to-volume ratio, increased septal wall thickness, diminished the number of alveolar crests, and increased the number of lamellar bodies in alveolar type II cells. However, this procedure did not alter quantitative lung growth (normal lung weights, volumes, and DNA and protein contents). Tissue prostaglandin content was decreased. The total amount of lung collagen or elastin was unchanged, but when collagen was analyzed into soluble and insoluble components, soluble collagen was increased. Supplementation with 1.0 g of prostaglandin E2 per 100 g body wt to animals treated with indomethacin reduced the abnormalities in pulmonary architecture. We conclude that indomethacin affects lung structure in growing rats and that it is an unusual model in that lung growth is normal, but lung development is abnormal. We also suggest that prostaglandins may play a significant role in alveolar formation in postnatal lung development in rats.

Animals↗
PubMed1995

Effect of T-kinin on microvascular permeability and its modulation by peptidases in rat airways.

T-kinin (Ile-Ser-bradykinin), the product of T-kininogen, has been found in rat plasma during systemic inflammation, but the effect of this kinin on airway inflammatory response is unknown. We examined the effect of T-kinin on vascular permeability in airways of anesthetized rats in vivo by using photometric measurement of the extravasated Evans blue. Intravenous injection of T-kinin (0.1-10 mumol/kg) increased dye extravasation in a dose-dependent manner, with 134% for trachea and 117% for bronchi by 1 mumol/kg. Pretreatment with bradykinin B2-receptor antagonist Hoe-140 (100 nmol/kg), but not the B1-receptor antagonist des-Arg9-Leu8-bradykinin (5 mg/kg), abolished plasma extravasation evoked by T-kinin (1 mumol/kg). NK1 tachykinin-receptor antagonist CP-99994 (4 mg/kg) did not affect T-kinin-induced vascular leakage. Pretreatment with captopril (2.5 mg/kg), angiotensin-converting enzyme inhibitor, potentiated T-kinin (100 nmol/kg)-induced plasma extravasation, whereas phosphoramidon (2.5 mg/kg), a neutral endopeptidase inhibitor, had no effect. We conclude that T-kinin produces airway vascular extravasation via stimulation of B2 receptors. The effect is modulated by endogenous angiotensin-converting enzyme and is not mediated via activation of sensory nerve.

Amino Acid Sequence↗
PubMed1995

Effect of erythromycin on endotoxin-induced microvascular leakage in the rat trachea and lungs.

To determine whether the macrolide antibiotic erythromycin prevents microvascular leakage produced by lipopolysaccharide (LPS), we studied tracheae and lungs of pathogen-free rats. Tracheal vascular permeability and neutrophil recruitment were assessed by the percent area occupied by Monastral blue-labeled blood vessels and by myeloperoxidase-containing granulocytes, respectively, in tracheal whole mounts. Pulmonary microvascular leakage was evaluated by lung wet-to-dry (W/D) weight ratio. Inhalation of Escherichia coli LPS (5 mg/kg) caused time-dependent increases in tracheal vascular permeability, neutrophil influx, and lung W/D ratio. These responses were inhibited by pretreatment with oral erythromycin, but not by ampicillin or cefaclor, in a dose-dependent manner: erythromycin at 10 mg/kg daily for 1 wk reduced the area density of Monastral blue-labeled vessels from 6.7 +/- 1.2 to 1.4 +/- 0.3% (p < 0.01), the number of neutrophils (from 365 +/- 51 to 149 +/- 30 cells/mm2, p < 0.01), and lung W/D weight ratio (from 6.76 +/- 0.30 to 5.39 +/- 0.21, p < 0.01). This inhibitory effect of erythromycin was abolished by depletion of circulating neutrophils with cyclophosphamide. These results suggest that LPS causes acute lung injury, microvascular leakage, and neutrophil recruitment in the trachea, and that erythromycin protects against these changes, probably by acting on neutrophils.

Ampicillin↗
PubMed1995

Cyclic adenosine monophosphate-mediated release of nitric oxide from canine cultured tracheal epithelium.

Nitric oxide (NO) may play a part in pulmonary vascular regulation and bronchomotor control and has been detected in exhaled air. We report the release of NO from airway epithelial cells and its regulation by cyclic adenosine monophosphate (cAMP). To directly measure NO release, a highly specific amperometric sensor for NO made of Pt/Ir alloy coated with a three-layered membrane consisting of KCI, NO-selective resin, and normal silicon resin was developed. Immersion of this sensor in the medium containing canine cultured tracheal epithelium detected baseline levels of NO at 9.6 +/- 1.6 nM (mean +/- SE), which was reduced by NG-nitro-L-arginine methylester (L-NAME) but not by D-NAME. This inhibition was reversed by L-arginine. Addition of isoproterenol, 3-isobutyl-1-methylxanthine, and forskolin caused a rapid increase in NO, an effect that was not altered by Ca(2+)-free medium in the presence of the intracellular Ca2+ chelator BAPTA-AM and the calmodulin antagonist W-7. Bradykinin, ionomycin, and ATP were without effect on NO release. The forskolin-induced NO release was accompanied by intracellular accumulation of cAMP and Ca2+. In contrast, bradykinin increased intracellular Ca2+ but not cAMP levels. Cytochemistry of cultured tracheal epithelium showed a positive staining with NADPH diaphorase activity. These results suggest that airway epithelial cells spontaneously release NO and that the release may be stimulated specifically through cAMP-dependent mechanism.

Animals↗
PubMed1995

Responsiveness and variability of airflow obstruction in chronic obstructive pulmonary disease. Clinicopathologic correlative studies.

We have studied the relationships between pulmonary lesions and bronchodilator response and variability of FEV1 in 41 patients enrolled in the National Institutes of Health Intermittent Positive Pressure Breathing Trial who died, came to autopsy, and provided adequate tissue to quantitate lesions. The patients had moderate to severe chronic airflow obstruction and various degrees of response to 250 micrograms isoproterenol inhalation. Airway responsiveness was positively correlated with bronchial eosinophilia, bronchial inflammation, and bronchiolar fibrosis, and it was negatively correlated with bronchiolar goblet cell metaplasia and emphysema. Patients with an increase of 190 ml or more in FEV1 after bronchodilator had less bronchial cartilage and less goblet metaplasia in bronchioles. Airway smooth muscle was not related to airway responsiveness and variability. Flow rates were adversely affected by bronchial eosinophilia for given emphysema scores. This study shows the importance of the eosinophil as part of chronic nonspecific lung disease. Lack of airway responsiveness was associated with lesions such as emphysema and goblet cell metaplasia, which by themselves cause severe chronic airflow obstruction. The better-preserved lung function in patients with increased airway responsiveness is attributed to negative correlations with emphysema and positive correlations with bronchial eosinophilia.

Bronchi↗
PubMed1995

A specific neutrophil elastase inhibitor (ONO-5046.Na) attenuates LPS-induced acute lung inflammation in the hamster.

We have examined the effect of ONO-5046.Na, a synthetic specific inhibitor of neutrophil elastase, on lipopolysaccharide (LPS)-induced acute lung inflammation. Syrian golden hamsters were injected intraperitoneally with either 300 mg.kg-1 of ONO-5046.Na or saline, 30 min before and 1 h after intratracheal administration of 0.1 mg.kg-1 LPS. Animals were sacrificed 2 and 24 h later and the wet-to-dry lung weight ratio (W/D) was determined. Bronchoalveolar lavage (BAL) was performed, and tissue sections were examined histologically. The effect of ONO-5046.Na on migration of isolated neutrophils was determined. W/D was not significantly different at 2 h, but was increased at 24 h in the LPS-treated animals. This increase was attenuated in the LPS-treated animals injected with ONO-5046.Na. Analysis of BAL fluid revealed that both at 2 and 24 h after LPS administration the total cell number and neutrophil number, albumin concentration, and elastase-like activity were significantly lower in the LPS-treated animals injected with ONO-5046.Na than in those given LPS alone. Histological examination of the lungs of the animals treated with LPS alone showed intra-alveolar haemorrhages and inflammatory cell infiltration 24 h after LPS administration, whereas the lungs of the LPS-treated ONO-5046.Na injected animals were only sparsely infiltrated by inflammatory cells, as indicated by the inflammation score.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effect of saiboku-to, an antiasthmatic herbal medicine, on nitric oxide generation from cultured canine airway epithelial cells.

The effect of Saiboku-to (TJ-96), an antiasthmatic Kampo medicine, on the generation of nitric oxide (NO) from cultured canine tracheal epithelium was investigated using a highly specific amperometric sensor for this molecule in vitro. Immersion of the NO-selective electrode in the medium containing tracheal epithelial cells detected the baseline current of 16.8-57.0 pA, which corresponded to an NO concentration ([NO]) of 39.7 +/- 8.1 nM. Addition of TJ-96 increased [NO] in a concentration-dependent manner, the maximal increase from the baseline level and the concentration of TJ-96 required to produce a half-maximal effect (EC50) being 127.5 +/- 20.1 nM (P < 0.001) and 86 +/- 9 micrograms/ml, respectively. Pretreatment of cells with NG-nitro-L-arginine methylester (L-NAME) greatly inhibited the TJ-96-induced increase in [NO], whereas NG-nitro-D-arginine methylester (D-NAME) had no effect, and this inhibition was reversed by L-arginine but not by D-arginine. Cytochemical staining of the epithelial cells showed marked reactivity of NADPH diaphorase activity. These results suggest that NO is spontaneously released by the airway epithelium and that TJ-96 stimulates the epithelial NO generation.

Animals↗
PubMed1995

A screening system for antiviral compounds against herpes simplex virus type 1 using the MTT method with L929 cells.

We developed the improved MTT assay system for in vitro evaluation of anti-HSV-1 agents using L929 cells derived from mouse connective tissue. This assay system provides results in 4 days using a 96-well microplate. The EC50 values of several anti-HSV agents (ACV, BVaraU, and others) were found to be similar to those obtained by the plaque reduction method using MRC-5 cells. The present MTT assay is rapid, accurate, and may be useful as an automatic screening system for evaluation of anti-HSV-1 compounds.

Animals↗
PubMed1995

[Role of nitric oxide in tachykinin-induced increase in Cl diffusion potential difference of rabbit tracheal mucosa].

To examine the effect of tachykinins on Cl secretion across tracheal mucosa and the possible contribution of nitric oxide (NO) formation to their actions in vivo, we measured Cl diffusion potential difference (Cl-PD) with a high-impedance voltmeter in the presence of amiloride. Superfusion of each neurokinin A (NKA) and substance P (SP) increased Cl-PD in a concentration-dependent fashion, whereas neurokinin B (NKB) had no effect, with the rank order of potency being NKA > SP >> NKB. The tachykinin-induced increase in Cl-PD was inhibited by the NO synthase inhibitor NG-nitro-L-arginine methylester (L-NAME), an effect that was reversed by L-arginine but not by D-arginine. These results suggest that tachykinins increase Cl secretion across rabbit trachea from the submucosa toward the lumen via stimulation of NK2 receptors and that NO formation may be involved in at least part of this process.

Animals↗
PubMed1995

Isoproterenol increases Cl diffusion potential difference of rabbit trachea through nitric oxide generation.

To determine whether nitric oxide (NO) formation is involved in Cl secretion across airway mucosa in response to beta adrenergic agonists, we studied the effect of isoproterenol (ISO) on the Cl diffusion potential difference of rabbit tracheal mucosa and measured NO formation by a highly specific electrode for this molecule in vivo. Perfusion of ISO on the tracheal mucosal surface increased the Cl diffusion potential difference, as determined in the presence of amiloride, in a dose-dependent fashion, the maximal increase from the base-line value being 12.1 +/- 1.7 mV (P < .001). Application of NG-nitro-L-arginine methylester (10(-3) M) decreased the Cl diffusion potential difference by itself and attenuated the subsequent response to ISO, causing a rightward displacement of ISO concentration-response curves, whereas NG-nitro-D-arginine methylester had no effect. This inhibitory effect of NG-nitro-L-arginine methyl-ester was reversed by L-arginine but not by D-arginine. Addition of ISO dose-dependently increased polarographic current and, hence, NO concentration in the perfusate, the maximal increase from the base-line levels being 178 +/- 10 nM. Histochemistry for NADPH diaphorase activity showed a strong staining within epithelial cells. These results suggest that NO formation may play a role in the beta adrenoceptor-mediated Cl secretion by tracheal mucosa.

Animals↗