Biomedical subjects

M Aubier

Publications and source records attributed to M Aubier.

At least 55 records · Page 3Linked to original sources

PubMed1999

Salmeterol/fluticasone propionate (50/500 microg) in combination in a Diskus inhaler (Seretide) is effective and safe in the treatment of steroid-dependent asthma.

This multicentre double-blind, double-dummy study compared the safety and efficacy of a new combination Diskus inhaler containing both salmeterol 50 microg and fluticasone propionate 500 microg (Seretide, GlaxoWellcome, France) with the same doses of the two drugs delivered via separate Diskus inhalers and with the same dose of fluticasone propionate alone. Patients were eligible for study entry if they had received an inhaled corticosteroid continuously for 12 weeks prior to run-in, and had received treatment with beclomethasone dipropionate or budesonide 1500-2000 microg day(-1) or fluticasone propionate 750-1000 microg day(-1) for at least 4 weeks prior to run-in. In total, 503 patients receiving inhaled corticosteroids were randomized to 28 weeks' treatment with either salmeterol/fluticasone propionate (50/500 microg) via a single Diskus inhaler (combination) and placebo, or salmeterol 50 microg and fluticasone propionate 500 microg administered via separate Diskus inhalers (concurrent), or fluticasone propionate 500 microg and placebo. All treatments were administered twice daily, mean morning peak expiratory flow rate (PEFR) and asthma symptoms were measured for the first 12 weeks and safety data were collected throughout the 28-week study. Over weeks 1 to 12, improvement in adjusted mean morning PEFR was 35 and 33 l min(-1), respectively, in the combination and concurrent therapy treatment groups (12 and 10% increase from baseline, respectively). The mean difference between treatments was -3 l min(-1) (90% confidence interval -10.4 l min(-1)) which was within the criteria for clinical equivalence. However, the combination therapy was statistically significantly superior to fluticasone propionate alone for mean morning PEFR (P<0.001) and other measures of lung function, whilst clinical equivalence of the combination and concurrent therapies was observed. All three treatments were well tolerated. In addition, there were no differences between the three treatments in either the c.hange in serum cortisol or urinary cortisol concentrations, which, for each treatment group, were no significantly different from baseline at the end of the treatment period. Thus, the combination of salmeterol and fluticasone propionate in a single inhaler is as well tolerated and effective in achieving asthma control in steroid-dependent patients as the separate administration of the two drugs, and both combination and concurrent therapy are superior to administration of the same dose of corticosteroid alone.

Administration, Inhalation↗

PubMed1999

Linking upper and lower airways.

BACKGROUND: Upper and lower airways are similar in many ways, including common triggers, pathogenic mechanisms, and response to treatment. Explanations for the posed linkage between upper and lower airways include nasal-bronchial reflux, postnasal drainage of inflammatory material into the lower airways, and dry air impinging on the nasal mucosa. CONCLUSION: Treatment modalities such as antihistamines and corticosteroid aerosols by the nasal route improve both the upper and lower airways.

Adrenal Cortex Hormones↗

PubMed1999

Differential effects of isoflurane and i.v. anaesthetic agents on metabolism of alveolar type II cells.

Alveolar type II (ATII) cells perform many important functions within the lung, including surfactant metabolism. We have investigated the effects of isoflurane and different i.v. anaesthetics on cell metabolism in primary cultures of rat ATII cells. Biosynthesis of phosphatidylcholine, the main phospholipid component of surfactant, was decreased in cells exposed to isoflurane in a dose- and time-related manner. This effect was fully reversible within 2 h after isoflurane removal. Lactate dehydrogenase (LDH) release, an index of cell damage, was increased with isoflurane exposure (1%) over a long incubation period (8-12 h). Enhanced lactate production, reflecting an increase in glycolytic metabolism, was also observed in isoflurane exposed cells. In contrast, metabolism of ATII cells was moderately affected by i.v. anaesthetics. Our data suggest differential metabolism of alveolar homeostasis depending on the anaesthetic agent used.

Anesthetics, Inhalation↗

PubMed1999

Endogenous peroxynitrite mediates mitochondrial dysfunction in rat diaphragm during endotoxemia.

It has been shown that nitric oxide (NO), synthesized by the inducible NO synthase (iNOS) expressed in the diaphragm during endotoxemia, participates in the development of muscular contractile failure. The aim of the present study was to investigate whether this deleterious action of NO was related to its effects on cellular oxidative pathways. Rats were inoculated with E. coli lipopolysaccharide (LPS) or sterile saline solution (controls) and studied at 3 and 6 h after inoculation. iNOS protein and activity could be detected in the rat diaphragm as early as 3 h after LPS, with a sustained steady-state concentration of 0.5 microM NO in the muscle associated with increased detection of hydrogen peroxide (H(2)O(2)). In vitro, the same NO concentration produced a marked increase in H(2)O(2) production by isolated control diaphragm mitochondria, thus reflecting a higher intramitochondrial concentration of nondiffusible superoxide anion (O(2)(-.)). In a similar way, whole diaphragmatic muscle and diaphragm mitochondria from endotoxemic rats showed a progressive increase in H(2)O(2) production associated with uncoupling and decreased phosphorylating capacity. Simultaneous with the maximal impairment in respiration (6 h after LPS), nitration of mitochondrial proteins (a peroxynitrite footprint) was detected and diaphragmatic force was reduced. Functional mitochondrial abnormalities, nitration of mitochondrial proteins, and the decrease in force were significantly attenuated by administration of the NOS inhibitor L-NMMA. These results show that increased and sustained NO levels lead to a consecutive formation of O(2)(-.) that reacts with NO to form peroxynitrite, which in turn impairs mitochondrial function, which probably contributes to the impairment of muscle contractility. during endotoxemia.

Animals↗

PubMed1999

Halothane stimulates a Na+H+ antiporter involved in the regulation of intracellular pH in alveolar epithelial cells.

UNLABELLED: Changes in intracellular pH (pHi) of alveolar type II (ATII) cells have been involved in the pathophysiology of pulmonary edema. ATII cells have evolved several ions transporters to regulate their pHi, including a Na+H+ antiporter. Because halothane alters the activity of ion transporters in various cells types, it may also affect the activity of this Na+H+ antiporter. This study was performed 1) to characterize a Na+H+ antiporter in a model of ATII cells and 2) to investigate the effect of halothane on the activity of this antiporter. ATII cells were obtained from primary rat ATII cells transfected with a mutant of simian virus SV40 large T antigen (SV40-T2), and their pHi was monitored using the pH-sensitive fluorescent probe 2'-7' (bis carboxyethyl)-5(6')-carboxyfluorescein. We demonstrated in vitro that 1) a Na+H+ antiporter (apparent Km 6.8 +/- 3.4 mM, Vmax 0.0105 +/- 0.0013 delta UpHi/s) regulates the pHi of SV40-T2 cells and 2) at clinically relevant concentrations (10(-3) to 10(-5) M) and for a short exposure duration (60 min), halothane enhances the activity of this antiporter. Because ATII cell acidification has been associated with alterations in the alveolar epithelial barrier, halothane-induced intracellular alkalinization might exhibit some protective effect in clinical situations, such as aspiration pneumonia. IMPLICATIONS: In vitro, halothane induces an intracellular alkalinization of pneumocytes II via the activation of a Na+H+ antiporter. Because acidification of these cells has been associated with alterations in the alveolar epithelial barrier, halothane might exhibit some protective effect in clinical situations, such as aspiration pneumonia.

Anesthetics, Inhalation↗

PubMed1999

Diesel exhaust particles are taken up by human airway epithelial cells in vitro and alter cytokine production.

The involvement of diesel exhaust particles (DEPs) in respiratory diseases was evaluated by studying their effects on two in vitro models of human airway epithelial cells. The cytotoxicity of DEPs, their phagocytosis, and the resulting immune response were investigated in a human bronchial epithelial cell line (16HBE14o-) as well as in human nasal epithelial cells in primary culture. DEP exposure induced a time- and dose-dependent membrane damage. Transmission electron microscopy showed that DEPs underwent endocytosis by epithelial cells and translocated through the epithelial cell sheet. Flow cytometric measurements allowed establishment of the time and dose dependency of this phagocytosis and its nonspecificity with different particles (DEPs, carbon black, and latex particles). DEPs also induced a time-dependent increase in interleukin-8, granulocyte-macrophage colony-stimulating factor, and interleukin-1beta release. This inflammatory response occurred later than phagocytosis, and its extent seems to depend on the content of adsorbed organic compounds because carbon black had no effect on cytokine release. Furthermore, exhaust gas posttreatments, which diminished the adsorbed organic compounds, reduced the DEP-induced increase in granulocyte-macrophage colony-stimulating factor release. These results suggest that DEPs could 1) be phagocytosed by airway epithelial cells and 2) induce a specific inflammatory response.

Biological Transport↗

PubMed1999

Alteration in diaphragmatic function induced by acute necrotizing pancreatitis in a rodent model.

Some of the common complications of acute necrotizing pancreatitis also involve pulmonary complications. These manifestations are often associated with a cephalad diaphragmatic shift. We hypothized that diaphragmatic function might be directly compromised by the acute abdominal process. This hypothesis was tested on an acute necrotizing pancreatitis (ANP) rat model. We assessed the diaphragm and peripheral (Extensor Digitorum Longus and Soleus) muscle properties in vitro using strips in control (C) and ANP animals. Contractile parameters included single twitch and a force-frequency curve (10 to 100 Hz), and an endurance capacity index (T50%) was calculated after a repetitive stimulation (30 Hz). Breathing pattern was not different between control and ANP animals, and muscular histologic examination was normal. However, ANP was associated with a marked decrease in diaphragmatic strength for all frequencies of stimulation when compared with C. Endurance capacity was also reduced in ANP animals as assessed by a lower T50% (ANP: 31 +/- 10.5 s; C: 49 +/- 10.3 s; p < 0.05). By contrast, no significant change in peripheral muscle function was observed in both groups. We conclude that ANP causes impairment in diaphragmatic strength and endurance capacity, whereas peripheral muscles are spared. These findings suggest that alterations in the respiratory pump may be involved in the genesis of acute respiratory failure in ANP.

Animals↗

PubMed1999

[Multicenter, controlled, double-blind study of the efficacy and tolerance of Vectrine (erdostein) versus placebo in the treatment of stabilized chronic bronchitis with hypersecretion].

The clinical efficacy of vectrine (erdosteine) was evaluated in the treatment of chronic bronchitis patients with hypersecretion during a controlled clinical trial having included 170 patients. For inclusion, the bronchitis patients had to be in a stable status (no exacerbation since at least three months). The patients received, in double-blind protocol, vectrine, one capsule b.i.d. or placebo, one similar capsule b.i.d. during a period treatment of 21 days. The results of the main evaluation criteria, the global index of efficacy (frequency of the cough + severity of the cough + difficulty in breathing + dyspnea) but also on the intensity and frequency of the cough were statistically significant in favor of vectrine. The safety of the treatment was excellent.

Administration, Oral↗

PubMed1998

Inducible expression of the alpha1-acid glycoprotein by rat and human type II alveolar epithelial cells.

Alpha1-acid glycoprotein (AGP) is a major acute phase protein in rat and human. AGP has important immunomodulatory functions that are potentially important for pulmonary inflammatory response. The liver is the main tissue for AGP synthesis in the organism, but the expression of AGP in the rat lung has not been investigated. We show that AGP mRNA was induced in the lung of dexamethasone-, turpentine-, or LPS-treated rats, whereas AGP mRNA was not detected in the lung of control rats. In the lung of animals treated intratracheally with LPS, in situ hybridization showed that AGP gene expression was restricted to cells located in the corners of the alveolus, consistent with an alveolar type II (ATII) cell localization. The inducible expression of the AGP gene was confirmed in vitro with SV40 T2 cells and rat ATII cells in primary culture: maximal expression required the presence of dexamethasone. IL-1 and the conditioned medium of alveolar macrophages acted synergistically with dexamethasone. Rat ATII cells secreted immunoreactive AGP in vitro when stimulated with dexamethasone or with a combination of dexamethasone and the conditioned medium of alveolar macrophages. In vivo, in the human lung, we detected immunoreactive AGP in hyperplastic ATII cells, whereas we did not detect AGP in the normal lung. We conclude that AGP is expressed in the lung in cases of inflammation and that ATII cells are the main source of AGP in the lung.

Acute-Phase Proteins↗

PubMed1998

[Pneumococci with diminished sensitivity to penicillin in pneumopathies. Clinical consequences].

INCREASING PREVALENCE: Since 1988, French clinicians have been faced with an increasing prevalence of penicillin-resistant pneumococcal pneumonia. In 1996, the percentage of strains with reduced susceptibility to penicillin reached more than 40% and the number of multiresistant strains has increased steadily. CLINICAL IMPACT: Despite this apparently alarming situation, the clinical impact is not obvious. Different clinical studies have demonstrated that mortality due to pneumococcal pneumonia has not been affected by the development of resistant strains, eventually because the strains involved belong to less invasive serotypes than penicillin susceptible pneumococci. HYPOTHESIS: The preferential distribution of penicillin resistance among less invasive serotypes might explain the development of resistance in carriage strains more often exposed to antibiotic selection and the greater risk for immunodepressed subjects to acquire these strains. PRACTICAL CONSEQUENCES: To date, first-line antibiotic therapy with amoxicillin at the dose of 3g/24 h remains valid for the great majority of cases. Use of much higher dosages or other antibiotics for pneumococcal pneumonia would only be rational when penicillin minimum inhibitory concentrations are above 2 mg/l.

Amoxicillin↗

PubMed1998

Role of nitric oxide on diaphragmatic contractile failure in Escherichia coli endotoxemic rats.

Contractile dysfunction of the respiratory muscles plays an important role in the genesis of respiratory failure during sepsis. Nitric oxide (NO), a free radical that is cytotoxic and negatively inotropic in the heart and skeletal muscle, is produced in large amounts during sepsis by a NO synthase inducible (iNOS) by LPS and/or cytokines. The aim of this study was to investigate whether iNOS was induced in the diaphragm of Escherichia coli endotoxemic rats and whether inhibition of iNOS induction or of NOS synthesis attenuated diaphragmatic contractile dysfunction. Rats were inoculated intravenously (IV) with 10 mg/kg of E. coli endotoxin (LPS animals) or saline (C animals). Six hours after LPS inoculation animals showed a significant increase in diaphragmatic NOS activity (L-citrulline production, P < 0.005). Inducible NOS protein was detected by Western-Blot in the diaphragms of LPS animals, while it was absent in C animals. LPS animals had a significant decrease in diaphragmatic force (P < 0.0001) measured in vitro. In LPS animals, inhibition of iNOS induction with dexamethasone (4 mg/kg IV 45 min before LPS) or inhibition of NOS activity with N(G)-methyl-L-arginine (8 mg/kg IV 90 min after LPS) prevented LPS-induced diaphragmatic contractile dysfunction. We conclude that increased NOS activity due to iNOS was involved in the genesis of diaphragmatic dysfunction observed in E. coli endotoxemic rats.

Animals↗

PubMed1998

Theophylline dilates rat diaphragm arterioles via the prostaglandins pathway.

1. We investigated by intravital microscopy in rats, the in vivo direct effects of theophylline on the diameters of second and third order diaphragm arterioles. 2. Theophylline (1-100 microM) dilated second and third order diaphragm arterioles significantly, and with an amplitude which was not statistically different from the one obtained with adenosine (1-100 microM). Enprofylline (1-100 microM), a theophylline analogue with poor adenosine-receptor antagonism but with similar or higher phosphodiesterases inhibition properties than theophylline, also dilated diaphragm arterioles, causing however, a significantly smaller dilatation than theophylline. 3. Neither the A1 adenosine receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (CPX, 50 nM), nor the A2 adenosine receptor antagonist 3,7-dimethyl-1-proparglyxanthine (DMPX, 10 microM) reduced significantly theophylline-induced arteriolar dilatation. 4. Theophylline (100 nM) abolished adenosine-induced arteriolar dilatation. 5. The dilatation induced by theophylline was unchanged by the nitric oxide (NO) synthase inhibitor N(omega)-nitro-L-arginine (NNA, 300 microM). 6. Theophylline-induced arteriolar dilatation was abolished by the prostaglandin synthesis inhibitors mefenamic acid or indomethacin (20 microM). 7. These findings show that theophylline induced a significant dilatation of diaphragm arterioles via the release of prostaglandins.

Adenosine↗

PubMed1998

Once-daily sparfloxacin versus high-dosage amoxicillin in the treatment of community-acquired, suspected pneumococcal pneumonia in adults. Sparfloxacin European Study Group.

The objective of this randomized, double-blind, multicenter study of 329 adult patients requiring hospitalization was to compare the safety and efficacy of sparfloxacin at a dosage of 200 mg once daily (following a 400-mg loading dose on day 1) with those of amoxicillin given as a 1-g oral dose three times daily for treatment of community-acquired pneumonia suspected to be due to Streptococcus pneumoniae. Success of treatment was determined by a combination of clinical assessment and chest radiography. Pneumococcal pneumonia was the confirmed diagnosis for 177 patients (54%). Overall rates of success among evaluable patients were equivalent between drugs, both at the end of treatment (sparfloxacin, 92%; amoxicillin, 87%) and at follow-up (sparfloxacin, 89%; amoxicillin, 84%). Sparfloxacin was well-tolerated and produced fewer gastrointestinal effects than amoxicillin. In conclusion, sparfloxacin is a safe and effective alternative to high-dose amoxicillin for the treatment of suspected pneumococcal community-acquired pneumonia.

Adult↗

PubMed1998

Effects of etomidate, propofol and thiopental anaesthesia on arteriolar tone in the rat diaphragm.

We have assessed, by intravital microscopy in rats, the effects of different anaesthetics on diaphragmatic arteriolar diameter. Rats were anaesthetized with etomidate, propofol or thiopental (groups E, P and T, respectively) and the diameters of the arterioles were measured sequentially at baseline and after topical application of either mefenamic acid (MA, 20 mumol litre-1) or N omega-nitro-L-arginine (NNA, 300 mumol litre-1), inhibitors of prostaglandins and nitric oxide, respectively. In group E, baseline arteriolar diameters were significantly higher than those in the two other groups (P < 0.01). MA and NNA induced significant constriction in the three groups (P < 0.001). However, whereas constriction induced by NNA was similar in the three groups, constriction induced by MA was significantly higher in group E compared with groups P and T (P < 0.05). We conclude that diaphragmatic arteriolar diameters in rats were greater during etomidate than during thiopental or propofol anaesthesia. This phenomenon may be mediated by prostaglandins.

Anesthetics, Intravenous↗

PubMed1998

Halothane decreases Na,K-ATPase, and Na channel activity in alveolar type II cells.

BACKGROUND: Halothane alters surfactant biosynthesis and metabolism of alveolar type II cells. In addition to synthesizing surfactant, alveolar type II cells actively transport sodium (Na) from the alveolar space to the interstitium. Na enters the cells through amiloride-sensitive Na channels or Na cotransporters and is extruded by a Na pump. The purpose of this study was to examine the effects of halothane on Na transport activities. METHODS: Epithelial type II cells from adult rat lungs were exposed to halothane concentrations of 1, 2, and 4% from 0.5-4 h. In some experiments, cells that were exposed to 1% halothane for 1 h were allowed to recover after replacement of the medium for 15 and 30 min. Na transport was then evaluated by direct measurement of radiolabeled ions uptake. In addition, the effects of halothane were assessed in the absence of extracellular calcium (Ca) with or without 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, an intracellular Ca chelating agent. RESULTS: Exposure of epithelial type II cells to halothane reduced the activity of sodium, potassium-adenosine triphosphatase, and amiloride-sensitive Na channels, whereas Na cotransporters were unchanged. The decrease in sodium, potassium-adenosine triphosphatase activity was maximal for 30 min of exposure and reached 50, 42, and 56% for halothane concentrations of 1, 2, and 4%, respectively, and did not change for longer exposure times. This effect was not prevented by either the absence of extracellular Ca or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid pretreatment. Exposure for 45 min to 1% halothane also decreased Na channel activity by 46%. These effects were completely reversible after 30 min of recovery. CONCLUSIONS: Sodium, potassium-adenosine triphosphatase, and amiloride-sensitive Na channel activities are impaired by halothane in alveolar type II cells in vitro. This inhibition could reduce transepithelial Na transport.

Alanine↗

PubMed1998

Diaphragmatic function is markedly altered in cerulein-induced pancreatitis.

OBJECTIVE: To assess diaphragmatic function in vitro during experimental cerulein-induced acute pancreatitis. DESIGN: Prospective, randomized, controlled animal trial. SETTING: Research laboratory at a large university medical center. SUBJECTS: Twenty male Sprague-Dawley rats, weighing 180 to 200 g. INTERVENTIONS: Sodium chloride 0.9% or cerulein (5 microg/kg/hr) was infused for 6 hrs. MEASUREMENTS AND MAIN RESULTS: Isometric force generated during electrical stimulation of costal diaphragmatic strips was measured 6 hrs after the end of infusion. Diaphragmatic strength was assessed at different frequencies (10, 20, 30, 50, and 100 Hz). Endurance index was the time until the force generated during the 30 Hz repetitive stimulation decreased to 50% of the initial value (T50%). Histologic examination of the diaphragm was performed. A decrease averaging 40% in diaphragmatic strength generation was observed for all frequencies of stimulation in the pancreatitis group. Compared with the control group, this decrease was associated with a reduction in T50% (30.9 +/- 12.5 [SD] and 46.4 +/- 10.8 secs in pancreatitis and control, respectively; p< .05). No histologic alteration of the diaphragm was observed. CONCLUSIONS: Acute pancreatitis induced marked diaphragmatic dysfunction. Although the precise mechanisms responsible for this alteration are not precisely determined, diaphragmatic dysfunction may play a role in pancreatitis-associated respiratory failure.

Acute Disease↗

PubMed1998

Myosin heavy chain gene expression changes in the diaphragm of patients with chronic lung hyperinflation.

In striated muscle, chronic increases in workload result in changes in myosin phenotype. The aim of this study was to determine whether such changes occur in the diaphragm of patients with severe chronic obstructive pulmonary disease, a situation characterized by a chronic increase in respiratory load and lung volume. Diaphragm biopsies were obtained from 22 patients who underwent thoracic surgery. Myosin was characterized with electrophoresis in nondenaturing conditions, SDS-glycerol PAGE, and Western blotting with monoclonal antibodies specific for slow and fast myosin heavy chain (MHC) isoforms. Flow volume curves, total lung capacity, and functional residual capacity were measured before surgery in 20 patients. We found that the human diaphragm is composed of at least four myosin isoforms, one slow and three fast, resulting from the combination of three MHC species. Chronic overload was associated with an increase in the slow beta-MHC species at the expense of the fast species (beta-MHC, 78.2 +/- 4.6 and 50.0 +/- 6.5% in emphysematous and control patients, respectively; P < 0.005). Linear correlations were found between beta-MHC percentage and forced expiratory volume in 1 s (r = -0.52; P < 0.02), total lung capacity (r = 0.44; P < 0.05), and functional residual capacity (r = 0.65; P < 0.003). The human adult diaphragm is composed of a balanced proportion of slow and fast myosin isoforms. In patients with chronic obstructive pulmonary disease, the proportion of fast myosins decreases, whereas that of slow myosin increases. This increase appears to be closely related to lung hyperinflation and may reflect an adaptation of the diaphragm to the new functional requirements.

Adult↗

PubMed1998

Oncostatin M is a potent stimulator of alpha1-antitrypsin secretion in lung epithelial cells: modulation by transforming growth factor-beta and interferon-gamma.

alpha1-Antitrypsin (alpha1-AT) plays a key role in lung homeostasis. Although the hepatocyte is considered as the primary source of alpha1-AT, we have previously demonstrated that rat alveolar epithelial type II cells as well as the human A549 cell line synthesize alpha1-AT, suggesting its local production within the lung. In the present study, we showed that oncostatin M, as opposed to interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), or IL-6, is a potent stimulator of alpha1-AT synthesis in the human A549 cell line. The oncostatin M-induced alpha1-AT secretion is modulated by interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) at both the protein and mRNA levels. IFN-gamma decreases oncostatin M-induced alpha1-AT secretion. By contrast, TGF-beta in combination with oncostatin M induces a dramatic and synergistic upregulation that is not observed in the HepG2 hepatocyte cell line. Our results suggest that during an inflammatory process, alveolar epithelial cells may contribute to the antiprotease defense within the lung.

Animals↗