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Biomedical subjects

K Kurashima

Publications and source records attributed to K Kurashima.

At least 19 recordsLinked to original sources
PubMed1998

Endosomal recycling of the Na+/H+ exchanger NHE3 isoform is regulated by the phosphatidylinositol 3-kinase pathway.

The NHE3 isoform of the Na+/H+ exchanger localizes to both the plasmalemmal and endosomal compartments in polarized epithelial and transfected Chinese hamster ovary (AP-1) cells. It is unclear how the distribution of NHE3 between these compartments is regulated. In this study, we examined the potential involvement of phosphatidylinositol 3'-kinase (PI3-K) in regulating the activity and distribution of NHE3, as this lipid kinase has been implicated in modulating vesicular traffic in the endosomal recycling pathway. Wortmannin and LY294002, both potent inhibitors of PI3-K, markedly inhibited NHE3-mediated H+ extrusion across the plasma membrane in a concentration- and time-dependent manner. The subcellular distribution of the antiporters was monitored by transfecting epitope-tagged NHE3 into AP-1 cells. In parallel with the inhibition of transport, PI3-K antagonists induced a pronounced loss of NHE3 from the cell surface and its accumulation in an intracellular compartment, as assessed by immunofluorescence microscopy and enzyme-linked immunosorbent assays. Further analysis using cells transfected with antiporters bearing an external epitope tag revealed that the redistribution reflected primarily a decrease in the rate of recycling of intracellular NHE3 to the cell surface. The wortmannin-induced inhibition and redistribution of NHE3 were prevented when cells were incubated at 4 degreesC, consistent with the known temperature dependence of the endocytic process. These observations demonstrate that NHE3 activity is controlled by dynamic endocytic and recycling events that are modulated by PI3-K.

Amino Acid Sequence↗
PubMed1997

Identification of sites required for down-regulation of Na+/H+ exchanger NHE3 activity by cAMP-dependent protein kinase. phosphorylation-dependent and -independent mechanisms.

We recently identified a region within the cytoplasmic C-terminal tail of the Na+/H+ exchanger NHE3 isoform (residues 579 to 684) which is essential for inhibition of transport activity by cAMP-dependent protein kinase (PKA) (Cabado, A. G., Yu, F. H., Kapus, A., Gergely, L., Grinstein, S., and Orlowski, J. (1996) J. Biol. Chem. 271, 3590-3599). To further define determinants of PKA regulation, six serine residues located in potential recognition sequences for PKA within, or adjacent to, this region (positions 552, 605, 634, 661, 690, and 691) were altered either independently or in various combinations using site-directed mutagenesis. Wild type and mutant NHE3s tagged with the influenza virus hemagglutinin epitope were stably expressed in exchanger-deficient Chinese hamster ovary cells (AP-1) for functional studies. Of the individual mutations examined, only substitutions at Ser605 or Ser634 affected sensitivity to forskolin, an activator of adenylate cyclase, although partial inhibition of NHE3 activity by forskolin remained. By contrast, simultaneous mutation of both these serines completely abolished cAMP-mediated inhibition of NHE3 without greatly affecting basal transport activity. Two-dimensional analysis of tryptic digests of immunoprecipitated NHE3 labeled in vivo with [32P]orthophosphate revealed several phosphopeptides under basal conditions. Phosphorylation was increased approximately 3-fold in one of these peptides following forskolin treatment, and this change was eliminated by mutation of residue Ser605. Thus, phosphorylation of Ser605 is essential for cAMP-mediated inhibition of NHE3. In addition, Ser634 is also required for the effect of cAMP, even though this residue does not become phosphorylated upon activation of PKA.

Amiloride↗
PubMed1997

Surface activity of sputum from acute asthmatic patients.

The cause of airway resistance that develops during an asthma attack is not fully understood. Besides bronchospasm and airway edema, a surfactant dysfunction has been suggested as a reason for an increase in airway resistance. This study sought to determine if surface activity of airway fluid is altered in acute asthmatic attacks. Sputa were collected serially from seven patients with acute asthmatic attacks and compared with that of normal subjects (n = 15) and subjects with stable asthma (n = 14). Sputa were analyzed for minimal surface tension (STmin), phospholipids (PL), and total proteins (TP). There were no significant differences in STmin, PL, and TP between sputa from normal subjects and subjects with stable asthma. In the acute phase of the attack, TP, TP/PL ratio, and STmin significantly increased. However, in the recovery phase of the attack, TP/PL ratio and STmin significantly decreased. These data demonstrated that surface properties of airway fluid deteriorated in the early phase of the asthma attack, but were ameliorated in the recovery phase possibly by the surfactant recruitment. The drastic changes in surface activity of sputum suggest that changes in airway surfactant may be partly involved in the pathogenesis of the airway obstruction during asthmatic attack.

Acute Disease↗
PubMed1997

Elevated chemokine levels in bronchoalveolar lavage fluid of tuberculosis patients.

In pulmonary tuberculosis, the proportion of lymphocytes, particularly that of CD4+ T lymphocytes, was increased in bronchoalveolar lavage fluid (BALF), reflecting their protective role against mycobacterial infections. In order to elucidate the mechanisms of lymphocyte accumulation in lungs, we measured the levels of chemokines with potent lymphocyte chemotactic activities, including interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and, regulated on activation, normal T-cell expressed and secreted (RANTES) present in BALF from patients with pulmonary tuberculosis in acute (n = 10) and convalescent phases (n = 6), as well as normal subjects (n = 10). During the acute phase of the disease, the proportions of lymphocytes and neutrophils were increased, as reported in previous studies. The levels of IL-8, MCP-1, and RANTES in the acute phase of pulmonary tuberculosis were also markedly elevated as compared with those of normal subjects. MCP-1 and RANTES, but not IL-8 levels present in BALF, decreased in the convalescent phase. Moreover, the concentration of RANTES correlated significantly with the absolute number of CD4+ cells in BALF. These data suggest that chemotactic cytokines are differentially produced and participate in the host response to Mycobacterium tuberculosis infection.

Bronchoalveolar Lavage Fluid↗
PubMed1997

A specific elevation of RANTES in bronchoalveolar lavage fluids of patients with chronic eosinophilic pneumonia.

Chronic eosinophilic pneumonia (CEP) is a rare, idiopathic lung disorder characterized pathologically by massive eosinophil infiltration into lung. In the bronchoalveolar lavage fluid (BALF) of patients with CEP, eosinophil numbers were markedly increased but returned to normal-levels upon the resolution of clinical symptoms, which suggests the crucial role of eosinophils in the pathogenesis of CEP. To clarify the mechanism of eosinophil accumulation in CEP, we determined the BALF levels of RANTES and macrophage inflammatory protein-1 alpha, two chemokines that predominantly exhibit in vitro eosinophil chemotactic activities. RANTES (106.7 +/- 27.2 pg/mg albumin; n = 16) concentrations in BALF from patients with CEP were significantly elevated in comparison with those of normal control subjects (1.4 pg/mg albumin; n = 13), whereas BALF macrophage inflammatory protein-1 alpha levels were not. In addition, eosinophils, lymphocytes, and macrophages in BALF were positively stained with a specific anti-RANTES antibody, which suggests that RANTES was produced locally in the lungs of CEP patients. Moreover, BALF-RANTES levels correlated significantly with the proportion of eosinophils in BALF. Furthermore, nearly half of the eosinophil chemotactic activities in BALF were abrogated by the anti-RANTES antibody in vitro. Collectively, these data suggest that locally produced RANTES is involved in eosinophil accumulation in the pulmonary alveolus and interstitium of patients with CEP.

Bronchoalveolar Lavage↗
PubMed1997

Effect of surfactant inhalation on allergic bronchoconstriction in guinea pigs.

BACKGROUND: In the small airway, surfactant reduces surface tension, prevents liquid filling of bronchioles, thereby maintaining patency in the small airways. Recent reports demonstrated that surfactant dysfunction develops in experimental asthma in immunized guinea pigs. However, there are few reports concerning surfactant and lung function in an experimental asthma model. OBJECTIVE: To examine whether inhaled surfactant improves lung mechanics in antigen-induced bronchoconstriction in guinea pigs. METHOD: We developed a passively immunized guinea pig model for allergic bronchoconstriction induced by antigen inhalation. Using this model, we investigated the effect of inhaled exogenous surfactant, surfactant TA, on the airway opening pressure (Pao) after antigen challenge. RESULTS: Aerosol antigen challenge produced a gradual and long-lasting increase in Pao. Twenty minutes after antigen challenge, aerosolized surfactant TA, 20 mg/ml, was inhaled for 90 s, and it significantly reduced the Pao by 32.8% in 12 min, while a 10.2% reduction was observed in a control group in the same period. When surfactant TA was administered by 90-s inhalation before antigen challenge, it inhibited the Pao increase in a dose-dependent manner: mean inhibitory rates of Pao were 33.6% in surfactant TA 10 mg/ml and 61.9% in surfactant TA 20 mg/ml, respectively. CONCLUSION: Inhaled surfactant showed preventive and recovery effects on antigeninduced bronchoconstriction in an immunized guinea pig model.

Administration, Inhalation↗
PubMed1996

Increase of chemokine levels in sputum precedes exacerbation of acute asthma attacks.

Basophils and eosinophils can be activated in vitro by several chemokines such as RANTES, monocyte chemotactic and activating factor (MCAF/MCP-1), macrophage inflammatory peptide-1 alpha (MIP-1 alpha), and interleukin-8 (IL-8). To explore the clinical relevance of the in vitro observations, we measured here the concentrations of these chemokines in sputa from asthmatic patients during acute attacks. Before the onset of a late-phase exacerbation, sputum MCAF/MCP-1, MIP-1 alpha, and IL-8 levels transiently but markedly increased from the basal levels in all of the patients with exacerbation, whereas the sputum levels of these chemokines remained unchanged during the course in the patients without a late-phase exacerbation. These results suggest the involvement of these chemokines in the late-phase exacerbation of asthma.

Acute Disease↗
PubMed1996

The role of vacuolar H(+)-ATPase in the control of intragranular pH and exocytosis in eosinophils.

The presence of vacuolar H(+)-ATPase (V-ATPase) on exocytotic granules in eosinophils and the role of this enzyme in exocytosis were explored in this study. Antibody against 116-kd subunit of V-ATPase positively stained eosinophil granules in immunofluorescence analysis. When eosinophil lysate was extracted immunomagnetically with the same antibody, the extracted fraction contained a considerable amount of eosinophil peroxidase, a marker of eosinophil-specific granules, which indicates that V-ATPase was present on the membranes of eosinophil exsosomal granules. The pH of the eosinophil granules, measured fluorometrically with acridine orange as a delta pH-sensitive dye, was estimated to be 5.1. The acidity of the eosinophil granules was perturbed by bafilomycin A1, a potent selective inhibitor of V-ATPase, which indicates that the low pH of these granules is maintained by V-ATPase activity. BafilomycinA1 and NH4Cl, both of which raise the intragranular pH to neutral, inhibited the eosinophil peroxidase exocytosis induced by platelet-activating factor. These agents did not, however, affect the changes in cytosolic free calcium concentration [Ca2+]i induced by platelet-activating factor. These observations suggest that bafilomycin A1 inhibited a delta pH-requiring step in eosinophil exocytosis that was preceded by the [Ca2+]i transient in the signal transduction pathway, and, hence, the findings suggest the pivotal role of V-ATPase in maintaining intragranular pH and its function of eosinophil exosomal granules.

Ammonium Chloride↗
PubMed1995

Effect of thromboxane A2 synthetase inhibitor, OKY-046, on sputum in chronic bronchitis and diffuse panbronchiolitis.

The mechanisms of excessive sputum production are only partially understood. We speculated that a selective thromboxane (Tx) A2 synthetase inhibitor, OKY-046, now used in the treatment of asthma in Japan, could decrease excess sputum production in patients with chronic airways disease. To test this hypothesis, we carried out a double-blind, placebo-controlled study of the effects of OKY-046, administered orally at 400 mg.day-1, on the sputum of patients with chronic bronchitis and patients with diffuse panbronchiolitis. Patients treated with OKY-046 showed a significant decrease (22%) in sputum volume after 1 month, and a 39% decrease after 3 months. Although the rheological properties of the sputum and the concentrations of fucose and immunoglobulin (Ig) A in the sputum remained unchanged, significant decreases were observed in the concentrations of total protein, albumin, sialic acid and phospholipid. Since albumin and fucose are chemical markers of plasma exudation and mucus secretion, respectively, whilst sialic acid and phospholipid are derived both from serum and mucus, our results indicate that this TxA2 synthetase inhibitor reduced sputum volume by inhibiting microvascular leakage in the airway. OKY-046 may, therefore, be of value in the treatment of chronic bronchitis and diffuse panbronchiolitis.

Adult↗
PubMed1994

Peripheral neuroectodermal tumor presenting pleural effusion.

Pleural effusion is a common finding of peripheral neuroectodermal tumor (PNET) of the chest wall (Askin's tumor), but little is known about the characteristics. A case of Askin's tumor with pleural effusion is reported. Repeated cytologies were negative for malignancy, but levels of lactic dehydrogenase (LDH) and neuron-specific enolase (NSE) in the pleural effusion were increased. Surgical biopsy was performed and immunohistochemical study of the tumor revealed the diagnosis.

Adult↗
PubMed1994

Inhibitory effect of aerosol administration of a sulfidopeptide leukotriene antagonist on bronchoconstriction induced by antigen inhalation in guinea pigs.

The effects of inhalation of the sulfidopeptide leukotriene antagonist AS-35 (9-[(4-Acetyl-3-hydroxy-2-n-propyl-phenoxy)methyl]-3-(1H- tetrazol-5-yl)-4H-pyrido [1,2-a]pyrimidin-4-one, CAS 108427-72-1) on bronchoconstriction induced by aerosol antigen, histamine, and leukotriene C4, D4 (LTC4, D4) were investigated in anesthetized and artificially ventilated guinea pigs. The increase in pressure at the airway opening (P(ao)) was measured as an index representing the grade of bronchial response. The bronchoconstriction induced by aerosol antigen was suppressed dose-dependently by pretreatment with inhaled AS-35 (0.1 mg and 1 mg) through a pressurized meter-dosed inhaler in the passively sensitized animals pretreated with diphenhydramine hydrochloride. But the histamine-induced bronchoconstriction was not altered by the pretreatment with AS-35 inhalation. On the other hand, LTC4- and LTD4-induced bronchoconstriction was inhibited by the pretreatment with aerosol AS-35 in a dose-dependent manner. The deposited dose of inhaled AS-35 in the peripheral airways was 3.5 micrograms and 6.5 micrograms when 0.1 mg and 1 mg of the drug was inhaled, respectively. These results suggest that sulfidopeptide leukotrienes (s-LTs) play an important role in the allergic bronchoconstriction in guinea pigs pretreated with antihistamine, and AS-35 inhalation may be beneficial in the treatment of asthma.

Administration, Inhalation↗
PubMed1993

Effect of inhaled procaterol on cough receptor sensitivity to capsaicin in patients with asthma or chronic bronchitis and in normal subjects.

BACKGROUND: To evaluate the effect of inhaled beta 2 adrenergic agonists on the sensitivity of airway cough receptors, the effect of inhaled procaterol on cough induced by aerosolised capsaicin, a stimulant of C fibres, was studied in patients with asthma or chronic bronchitis and in normal subjects. METHOD: Eleven patients with asthma and 10 with chronic bronchitis and 14 normal subjects participated. Increasing concentrations of capsaicin solution were inhaled for 15 seconds by tidal breathing through the mouth at one minute intervals until five or more coughs were elicited, before and 30 minutes after inhalation of 20 micrograms procaterol or placebo (freon gas alone) through a metered dose inhaler. Cough threshold was defined as the lowest concentration of capsaicin that elicited five or more coughs. To evaluate the bronchodilator effect of procaterol and the bronchoconstrictor effect of inhaled capsaicin, forced expiratory volume in one second (FEV1) was measured before and one minute after a capsaicin provocation test. This test was carried out both before and 30 minutes after treatment with procaterol or placebo. RESULTS: The geometric mean value of cough threshold to capsaicin was significantly increased by procaterol and placebo in both groups of patients but not in the control subjects. The increment in the cough threshold was not significantly different between the treatments with procaterol and placebo in each group. FEV1 was significantly increased by procaterol but not by placebo in all three groups. CONCLUSIONS: Inhaled procaterol has no effect on airway cough receptor sensitivity to capsaicin. The attenuation of the cough sensitivity seen after inhalation of procaterol in patients with asthma and bronchitis may result from tachyphylaxis to capsaicin.

Administration, Inhalation↗
PubMed1992

[Analysis of bronchoalveolar lavage fluid in patients before and after bone marrow transplantation].

We analysed BALF cell findings in 9 patients (group A: 5 patients without lung disease after bone marrow transplantation (BMT), group B: 4 patients with lung disease after BMT) before and after BMT. Before BMT, BALF cell findings in group A were almost normal, whereas a relative increase of lymphocytes was seen in group B. Although total cell counts and cell composition in group A changed little after BMT, CD4/CD8 ratios in BALF lymphocytes decreased. In contrast, a relative increase of lymphocytes and neutrophils was seen in group B and there was variation of CD4/CD8 ratios in BALF lymphocytes after BMT. We there studied the BALF lymphocytes of 3 patients in group A and 4 patients in group B after BMT by means of 2-color analysis. Among CD4+ cell populations, CDw 29+ cells were decreased in both groups after BMT. A relative increase of BALF-CD4+ HLA-DR+ cells and CD8+ HLA-DR+ cells was seen in group A, but was not seen in group B. These findings suggest that there is abnormality of local immunity in the lung after BMT.

Adult↗
PubMed1992

Thromboxane A2 synthetase inhibitor (OKY-046) improves abnormal mucociliary transport in asthmatic patients.

The effect of a thromboxane A2 synthetase inhibitor (OKY-046, 400 mg po/day) on mucociliary transport was investigated in 19 asthmatic patients. The nasal clearance time, as measured by the saccharin test, was prolonged in asthmatics (60.2 +/- 8.4 SE min) compared with normal controls (15.1 +/- 3.4 SE min). Within 4 weeks after OKY-046 administration, the nasal clearance time had improved (27.4 +/- 4.4 SE min, P less than .01) and the amount of sputum had decreased 30% (P less than .01). These results indicate that thromboxane A2 plays an important role in mucociliary transport in patients with asthma.

Aged↗
PubMed1991

Activity of pulmonary surfactant after blocking the associated proteins SP-A and SP-B.

To investigate the role of the pulmonary surfactant-associated proteins SP-A and SP-B, the respective monoclonal antibody (anti-A or anti-B) was added to porcine pulmonary surfactant at a weight ratio of 1:2, and the mixtures were tested on surfactant-deficient immature newborn rabbits (gestational age 26 days). Under pentobarbital sodium anesthesia and mechanical ventilation with a 25-cmH2O peak insufflation pressure, the tidal volumes of the animals given surfactant alone and of those given surfactant containing anti-A were 27.9 +/- 5.1 and 25.1 +/- 9.6 (SD) ml/kg, respectively, whereas that of those given surfactant with anti-B was 5.8 +/- 3.6 ml/kg (P less than 0.05). The surface adsorption times of surfactant alone and of anti-A-containing surfactant were less than 0.8 s compared with greater than 120 s (P less than 0.01) for anti-B-containing surfactant. The anti-B suppressed the surfactant activity until the weight ratio was decreased to 2:100. The role of SP-A could not be clarified, but it was concluded that SP-B is an essential factor for surfactant activity.

Animals↗
PubMed1991

[Inhibitory effects of rhIL-1 beta pretreatment on bleomycin-induced pneumonitis in mice].

We studied the effects of recombinant human interleukin-1 beta (rhIL-1 beta) pretreatment on bleomycin (BLM)-induced pneumonitis in mice. Lung injury was dose-dependently induced by BLM (50 mg/kg, 100 mg/kg, 150 mg/kg i.v.). The mice were pretreated with IL-1 (1 microgram/mouse i.p.) at 0.5, 6, 12 or 24 hours before the administration of BLM. Wet lung weight, lung weight-to-body weight ratio and bronchoalveolar lavage cell findings were analyzed with respect to time, and lung specimens on day 28 after administration of BLM were histopathologically examined. When mice were pretreated with IL-1 at 0.5 hr or 6 hr before the administration of BLM, changes in all the parameters were significantly suppressed. The results indicate that IL-1 pretreatment protects mice from BLM-induced pneumonitis and its effects are time-dependent.

Animals↗