Biomedical subjects

L Pineau

Publications and source records attributed to L Pineau.

At least 19 recordsLinked to original sources

PubMed2002

Interactions between biocide cationic agents and bacterial biofilms.

The resistance of bacterial biofilms to physical and chemical agents is attributed in the literature to various interconnected processes. The limitation of mass transfer alters the growth rate, and physiological changes in the bacteria in the film also appear. The present work describes an approach to determination of the mechanisms involved in the resistance of bacteria to quaternary ammonium compounds (benzalkonium chloride) according to the C-chain lengths of those compounds. For Pseudomonas aeruginosa CIP A 22, the level of resistance of the bacteria in the biofilm relative to that of planktonic bacteria increased with the C-chain length. For cells within the biofilm, the exopolysaccharide induced a characteristic increase in surface hydrophilicity. However, this hydrophilicity was eliminated by simple resuspension and washing. The sensitivity to quaternary ammonium compounds was restored to over 90%. Staphylococcus aureus CIP 53 154 had a very high level of resistance when it was in the biofilm form. A characteristic of bacteria from the biofilm was a reduction in the percent hydrophobicity, but the essential point is that this hydrophobicity was retained after the biofilm bacteria were resuspended and washed. The recovery of sensitivity was thus only partial. These results indicate that the factors involved in biofilm resistance to quaternary ammonium compounds vary according to the bacterial modifications induced by the formation of a biofilm. In the case of P. aeruginosa, we have underlined the involvement of the exopolysaccharide and particularly the three-dimensional structure (water channels). In the case of S. aureus, the role of the three-dimensional structure is limited and drastic physiological changes in the biofilm cells are more highly implicated in resistance.

Animals↗

PubMed2000

Antimicrobial resistance of mesophilic Aeromonas spp. isolated from two European rivers.

The activity of 19 antibiotics and four antiseptics and/or disinfectants was studied against 138 non-redundant strains of Aeromonas spp. (104 Aeromonas caviae, 22 Aeromonas sobria and 12 Aeromonas hydrophila) isolated from two European rivers. Antibiotic resistance frequencies were: nalidixic acid, 59%; tetracycline, 14%; fosfomycin, 8%; tobramycin and cotrimoxazole, 7%; cefotaxime, 4%; chloramphenicol, 2%; gentamicin, 1%. Most of the nalidixic acid-resistant strains were susceptible to fluoroquinolones (54-98%). Antibiotic resistance rates varied according to the source of the strains. All Aeromonas spp. strains were killed by 50 ppm of chlorine, cetylpyridinium chloride and peracetic acid, and by 1600 ppm of glutaraldehyde.

Aeromonas↗

PubMed1997

Automatic washer disinfector for flexible endoscopes: a new evaluation process.

BACKGROUND AND STUDY AIMS: Many automatic washer disinfectors for flexible endoscopes have been marketed and offered as an alternative method of preventing infections, but they are frequently unsatisfactory. There is therefore clearly a need to test prototypes prior to marketing, following an evaluation process that is sufficiently reliable and rigorous to guarantee the efficacy of the decontamination processes. MATERIALS AND METHODS: The present study describes an experimental method based on the follow-up of the decontamination of a Tygon tube, the internal surface of which was contaminated by a bacterial biofilm. This method is proposed as a preliminary test for evaluating washer disinfectors. RESULTS: An analysis of the results obtained after technical modifications of the first prototype of the Fibro-Cleaner showed that complementary activities of each successive cycle phase allow a reduction in the number of adherent bacteria of more than 8 log per cm2 of support. With the three different biofilms tested (Escherichia coli, Pseudomonas aeruginosa mucoid and Staphylococcus aureus), no microorganisms were recovered from the support at the end of the decontamination process. CONCLUSIONS: The experimental protocol suggested here seems to be well suited for assessing washer disinfectors during the development phase of the prototype, as well as for comparative studies.

Biofilms↗

PubMed1995

Incapacity and autonomy: striking a balance.

We want to take this opportunity to offer our perspective on some of the issues to which the Substitute Decisions Act, 1992, and the Consent to Treatment Act, 1992, represent a response. To a lesser extent, the provisions of the Advocacy Act, 1992, which governs the provision and role of advocates, will be considered. First, we hope to explain, perhaps a little more than can be done in Committee, or in the Legislature, the thinking that underlies some of the protective measures this legislation makes available to persons who are thought to be mentally incapable. Second, we provide some discussion of the problem of the criterion of mental capacity, and argue that where there is no strict criterion, it is important to ensure that individuals who are subjects of assessments of their mental capacity are protected by a balance of power in which they hold a prominent position. Third, we suggest that the lack of a strict criterion of capacity argues for a broad criterion for assessors.

Advance Directives↗

PubMed1986

Lack of acute effects of ascorbic acid on spirometry and airway responsiveness to histamine in subjects with asthma.

Sixteen adult subjects with asthma in a clinical steady state were studied. On day 1, after baseline spirometry, they underwent four histamine inhalation tests with functional recovery between each test. The provocative concentration causing a 20% fall in FEV1 (PC20) was obtained after each test. On days 2, 3, and 4, after baseline spirometry, active and placebo ascorbic acid (2 gm) was administered orally, double-blind, according to a 4.3.1 two-treatment crossover study design. One hour later, spirometry was performed, and PC20 was reassessed. We found no significant changes in FEV1 and FVC after ascorbic acid as compared with placebo administration. There was no difference between PC20 on days 2, 3, and 4 and by standardizing for the four PC20 results obtained on day 1. We conclude that ascorbic acid has no acute bronchodilator effect and does not alter bronchial responsiveness to histamine in subjects with asthma.

Adult↗

PubMed1986

Occupational asthma caused by eastern white cedar (Thuja occidentalis) with demonstration that plicatic acid is present in this wood dust and is the causal agent.

A worker developed symptoms of work-related asthma a few weeks after starting to work in a sawmill where eastern white cedar (Thuja occidentalis) was transformed into shingles. The diagnosis of occupational asthma was confirmed by monitoring of peak expiratory flow rates and bronchial responsiveness to histamine off work and at work, and specific inhalation challenges in the laboratory that demonstrated an isolated late asthmatic reaction after exposure for 4 hours to the wood dust. Specific inhalation challenges with western red cedar (thuja plicata) for 2 hours and plicatic acid (PA) for 7 minutes also caused an isolated late asthmatic reaction. Elevated specific IgE levels to PA were present. Antiserum was produced in rabbits that were immunized with PA conjugated to human serum albumin. With this antiserum in inhibition experiments, cross-reactivity between western red cedar and eastern white cedar, both belonging to the family of arborvitae, was found. It is estimated that eastern white cedar contains approximately half the amount of PA present in western red cedar.

Adult↗

PubMed1985

Follow-up of occupational asthma caused by crab and various agents.

Sixty-three subjects with occupational asthma caused by crab (n = 31) and various other agents (n = 32) were studied after cessation of exposure at work for mean +/- SD intervals of 12.3 +/- 5.5 and 24.5 +/- 18.7 months (greater than 6 months in every subject), respectively. Nineteen of the subjects with asthma caused by crab and 30 of the subjects with asthma caused by various agents were still symptomatic of asthma, nine subjects of the latter group requiring bronchodilators (with inhaled beclomethasone in five) regularly. No significant changes in baseline spirometry were observed at the time of follow-up as compared with initial assessment, nine subjects (all in the asthma group caused by various agents) demonstrating significant bronchial obstruction. Improvement in bronchial responsiveness to histamine was significant (p less than 0.01) in the group with asthma caused by crab but not in the other group. Forty-eight of 52 subjects still had significant airway hyperexcitability. Subjects with asthma caused by crab who were asymptomatic and those subjects with asthma caused by various agents who used bronchodilators only if they were needed had worked for shorter intervals after onset of symptoms (p less than 0.01 and p less than 0.05, respectively). It is concluded that subjects with occupational asthma caused by various agents can remain symptomatic of asthma and demonstrate a persistence of bronchial obstruction and hyperexcitability for prolonged intervals after cessation of exposure.

Adult↗

PubMed1985

Occupational asthma due to azobisformamide.

Azobisformamide is a low molecular weight agent used in the plastic industry as a foaming product. Two subjects with a history of work-related asthma in association with exposure to azobisformamide underwent specific inhalation tests. One subject developed an isolated late asthmatic response, whereas in the other a dual reaction was observed.

Adult↗

PubMed1985

Slope of the dose-response curve to inhaled histamine and methacholine and PC20 in subjects with symptoms of airway hyperexcitability and in normal subjects.

Slopes of the dose-response curves to inhaled histamine or methacholine and PC20 were compared in 14 subjects with symptoms of bronchial hyperexcitability and in 10 normal subjects. Slopes were obtained by analyzing curves with 3 to 6 points by the least squares method. Only curves with satisfactory correlation coefficients corresponding to p values less than 0.05 were kept for analysis. Twelve of the 14 subjects with symptoms of bronchial hyperexcitability and 1 of the 10 normal subjects had slopes greater than 20 (percent change in FEV1/log histamine or methacholine concentration) (chi-square = 13.5, p less than 0.001). Eleven of the 14 subjects with symptoms of bronchial hyperexcitability and 1 of the 10 normal subjects had PC20 results less than or equal to 16 mg/ml (chi-square = 11.0, p less than 0.001). It is concluded that, using the method described in our study, slopes of the dose-response curve to inhaled histamine or methacholine are different in subjects with and without symptoms of bronchial hyperexcitability.

Adult↗

PubMed1984

Occupational asthma in snow crab-processing workers.

The prevalence of occupational asthma was studied in two snow crab-processing industries in operation since 1980. Before the 1982 season, all except 10 of the 313 employees were investigated by a questionnaire, prick skin tests with common allergens, crab n and crab-boiling water extracts, and spirometry. The diagnosis was confirmed in 46 (15.6%) workers (including 33 of 64 subjects with a history highly suggestive of occupational asthma in the previous seasons) by (1) specific inhalation challenges in 33 subjects (one immediate, nine dual, and 23 late asthmatic responses) and/or (2) a combination of monitoring of peak expiratory flow rates (n = 12) and significant changes in bronchial responsiveness to histamine (n = 16) as well as in spirometry (n = 18) after reappearance of symptoms on return to work. Positive skin tests to crab (p less than 0.001) and, to a lesser degree, smoking history (p = 0.03) but not atopy (p greater than 0.05) were related to the presence of occupational asthma. A high prevalence of rhinoconjunctivitis (35 of 46) and urticaria (16 of 46) was also documented in the affected individuals.

Asthma↗

PubMed1984

Occupational asthma due to pepsin.

A 30-year-old atopic worker exposed to pepsin powder, herb, and pollen extracts at work developed an increase in asthmatic symptoms. Monitoring of peak expiratory flow rate revealed more important fluctuations at work. Skin prick tests yielded a large immediate reaction to pepsin. Specific inhalation challenges confirmed the diagnosis; an intense early response was documented after exposure to pepsin. The pepsin IgE RAST was positive and selectively inhibited by pepsin.

Adult↗

PubMed1984

Effect of sodium cromoglycate on histamine inhalation tests.

Sixteen adult asthmatic subjects in a clinical steady state were included in the study. On day 1, after baseline assessment of spirometry (FEV1, FEV1/FVC, FEF25-75), they underwent three to four consecutive inhalation tests using twofold increasing doses of histamine to measure the provocative concentration causing a fall in FEV1 of 20% (PC20). Baseline FEV1 was back to +/- 5% of the initial assessment before each histamine inhalation test (HIT). On days 2, 3, and 4, after baseline spirometry which confirmed that FEV1 was within 10% of initial day 1 assessment, placebo-lactose (P) or 40 mg of sodium cromoglycate (SCG) were nebulized in a double-blind randomized 4.3.1. two-treatment crossover study design. Ten minutes later, spirometry was repeated and followed by an HIT. Baseline spirometry was not significantly different on each day or after P and SCG. There was no statistical difference between the geometric means of the three or four PC20's done on day 1, indicating that there is no tachyphylaxis induced by repeated HIT. There was no statistical difference between mean PC20 after P (0.52 +/- 3.3 (SD) mg/ml), after SCG (0.50 +/- 3.2), and of the three to four HIT done on day 1 (0.40 +/- 3.6). We conclude that in asthmatic subjects SCG has no acute bronchodilator effect and does not alter the response to inhaled histamine.

Adult↗

PubMed1984

Monitoring of maximum expiratory peak flow rates and histamine inhalation tests in the investigation of occupational asthma.

A 49 year old carpenter developed asthma after he was employed in a new workshop. Specific inhalation tests carried out in a laboratory with presswood sawdust and the different glues used at work were negative. Monitoring peak expiratory flow rates (PEFR) at work revealed a progressive fall on consecutive days with recovery after periods off-work. Histamine inhalation tests showed a definite increase in bronchial hyperexcitability after working periods. Monitoring of PEFR in conjunction with histamine inhalation tests can thus help in confirming occupational asthma.

Asthma↗

PubMed1984

Histamine phosphate has a cumulative effect when inhaled at five minute intervals.

As the duration of bronchoconstriction induced by inhaled histamine phosphate is greater than five minutes, a study was carried out to determine whether this leads to a cumulative effect when histamine is inhaled at five minute intervals as in standardised procedures. Fourteen clinically stable adult asthmatic subjects were studied. In the first part of the study (the noncumulative stage) they inhaled doubling concentrations of histamine until appreciable bronchoconstriction occurred (changes close to 50% in lung resistance for seven subjects and 15% in forced expiratory volume in one second for seven others). After functional recovery the last concentration of histamine was nebulised on two more occasions, allowing for functional recovery after each nebulisation. In the second part of the study (the cumulative stage) subjects inhaled, depending on their responsiveness, three to eight consecutive doses of the histamine concentration last administered in the non-cumulative stage, these doses being administered at five minute intervals, without recovery. The cumulative effect was assessed by linear regression analysis of the changes in the specific functional indices, all the values obtained during the non-cumulative stage being given the score 0 and those obtained during the cumulative step scores of 1, 2, etc. In all but one instance significant (p less than 0.01) correlations were obtained and the slopes were positive, thus showing a cumulative effect. It is concluded that histamine has a cumulative bronchoconstrictor effect if inhaled at five minute intervals once appreciable bronchoconstriction has been reached.

Adult↗

PubMed1984

Bronchial responsiveness to methacholine and effects of respiratory maneuvers.

Eight asthmatic and six normal subjects had methacholine chloride inhalation tests on two visits. On first assessment the provocative concentration causing a 20% fall in forced expiratory volume in 1 s (PC20FEV1) was measured. On the second visit the provocative concentration causing a 35% fall in specific lung conductance (PC35sGL) was obtained in addition to the PC20FEV1. Lung resistance was continuously monitored to evaluate the bronchomotor effect of FEV1 maneuver. Results of PC20FEV1 were within one single twofold concentration on the two visits. In all subjects but one PC35sGL was lower than PC20FEV1, and in 10 instances this difference was superior to a single twofold concentration. The bronchodilator effect of FEV1 maneuver was significantly although loosely related to base-line airway caliber and excitability. However, we were unable to show a significant relationship between the differences between PC20FEV1 and PC35sGL and this bronchodilator effect. This suggests that other factors may explain the greater sensitivity of PC35sGL compared with PC20FEV1.

Asthma↗

PubMed1984

Nonallergic bronchial hyperexcitability in chronic bronchitis.

The aim of this study was to assess responsiveness to inhaled histamine and methacholine using PC20, the concentration causing a 20% fall in forced expiratory volume in one second (FEV1) in 28 subjects with chronic bronchitis excluding asthma. Eighteen subjects had airway hyperexcitability, as demonstrated by a PC20 less than 16 mg/ml. The response to histamine and methacholine was not significantly different and the correlation coefficient was 0.75. Baseline airway caliber was related to the level of hyperexcitability, as 14 of 14 subjects with a FEV1 to forced vital capacity ratio less than 95% pred and/or a forced expiratory flow during the middle half of the FVC less than 80% pred, and only 4 of 10 subjects with normal spirometry, had a PC20 less than 16 mg/ml (x2 = 15.6, p less than 0.001). There was no correlation between blood or sputum eosinophilia, total IgE levels, or atopy and the level of airway hyperexcitability. Spontaneous daily variations of peak expiratory flow rates were significantly (t = 2.43, p less than 0.05) more pronounced in subjects with PC20 less than 16 mg/ml. We conclude that airway hyperexcitability assessed with PC20 is often present in chronic bronchitis and more often so in the presence of airway obstruction.

Bronchi↗

PubMed1983

Reference values of the provocative concentrations of methacholine that cause 6% and 20% changes in forced expiratory volume in one second in a normal population.

The provocative concentrations of inhaled methacholine that cause 6% (PC6) and 20% (PC20) falls in forced expiratory volume in one second (FEV1) were assessed in a population of 100 nonsmoking persons, equally distributed for sex, who ranged uniformly from 20 to 60 yr of age. These subjects had no respiratory symptoms, rhinitis, atopic history, or familial history of asthma. Single twofold dilutions of methacholine from 2 to 128 mg/ml were used; 81 and 34 subjects, respectively, showed PC6 and PC20 values less than 128 mg/ml. Eight subjects had PC20 values less than 16 mg/ml. In these subjects, the test had a good reproducibility (r = 0.92) when we repeated it, and serial measurements of peak expiratory flow rates did not suggest asthma. The fact that PC6 was related, although loosely, to baseline FEV, FEV/FVC, and forced expiratory flow during the middle half of the FVC (FEF) and that 4 of the 8 subjects with PC20 values less than 16 mg/ml had lower values of FEF might suggest that responsiveness to methacholine is partially linked with baseline airway caliber.

Adult↗

PubMedDate not supplied

Pulmonary function tests and airway responsiveness to methacholine in chronic bronchiectasis of the adult.

Fifty adults with chronic bronchiectasis (mean duration since diagnosis: 25 +/- 16.4 years), excluding those cases secondary to tuberculosis or hypogammaglobulinemia, were investigated by a questionnaire, a chest radiograph and lung function tests. Of these, 29 with an FEV1 greater than 1.5 1 underwent methacholine inhalation tests. Fourty-three subjects and three subjects respectively showed an obstructive or a mixed obstructive and restrictive defect, only four having normal lung function tests. Sixty-nine percent of subjects tested had a provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) less than 16 mg X ml-1. Subjects with daily sputum production had lower values of FEV1 and FEV1/forced vital capacity (FVC) compared to subjects with less than daily sputum. Subjects with clinical features of bronchial hyperexcitability had significantly lower baseline FEV1, vital capacity, and maximal mid-expiratory flow rate (FEF25-75). Subjects with lower PC20 values had significantly lower baseline FEV1, FEV1/FVC and FEF25-75. Finally, subjects with the greatest extent of radiological abnormalities had lower baseline FEV1, FEV1/FVC and diffusing capacity, and a higher residual volume. We conclude that chronic bronchiectasis is associated with significant changes in lung function tests and increased responsiveness to methacholine in the majority of affected individuals.

Adult↗