Biomedical subjects

A Cartier

Publications and source records attributed to A Cartier.

At least 145 records · Page 8Linked to original sources

PubMed1988

Theophylline minimally inhibits bronchoconstriction induced by dry cold air inhalation in asthmatic subjects.

The aim of this study was to evaluate the effect of a sustained-release theophylline preparation on bronchial responsiveness to cold dry air inhalation in asthmatic subjects. Sixteen adult subjects with asthma in a clinical steady state underwent 3 isocapnic cold air challenges on 3 consecutive days at a time when they had not received oral theophylline medication over the past 3 days. The dose of cold air causing a 20% (PD20) fall in FEV1 was obtained from each subject's dose-response curve. Subjects were then administered active or placebo sustained-release theophylline preparations according to a double-blind, randomized, two-treatment crossover design. Medication was given for a minimum of 3 consecutive days. PD20 was reassessed on 4 different days, 3 to 4 h after receiving active or placebo medication (two visits for each medication). We found a significant bronchodilator effect of theophylline as compared to the placebo (mean +/- SD differences in changes of FEV1 of 8.8 +/- 1.9%). We also documented a significant blocking effect of the active medication as opposed to the placebo on PD20 (p = 0.01). This difference (mean = 0.18 on the loge scale) was statistically beyond the intraindividual between-day variability observed on the 3 control days (p less than 0.001) but was physiologically minimal. This blocking effect was also partially related to changes in airway caliber. We conclude that theophylline showed a blocking effect on bronchial responsiveness to dry cold air, which was physiologically minimal and was partially related to changes in airway caliber.

Adolescent↗

PubMed1988

Patterns of improvement in spirometry, bronchial hyperresponsiveness, and specific IgE antibody levels after cessation of exposure in occupational asthma caused by snow-crab processing.

Thirty-one workers with occupational asthma caused by snow-crab processing were assessed by a long-term follow-up on three occasions at mean +/- SD intervals of 12.8 +/- 5.4, 31.4 +/- 6.3, and 64.4 +/- 6.3 months after leaving work. The diagnosis of work-related asthma was initially confirmed in all of them by specific inhalation challenges at the workplace or by laboratory inhalation of snow-crab boiling water (n = 24) or by serial monitoring of airway caliber and bronchial responsiveness to histamine at work and off work (n = 7). Total duration of work-related exposure was 12.8 +/- 5.6 months (range, 3 to 21 months), and the duration of symptoms after onset was 6.8 +/- 4.2 months (range, 1 to 18 months). At the time of diagnosis, all 31 subjects required medication for asthma, 11 had a FEV1 less than or equal to 85% predicted, and all subjects had a PC20 less than or equal to 16 mg/ml. Twelve of 25 serum samples assessed showed high levels of specific immunoglobulin E (IgE) antibodies to crab meat and/or boiling water. At the time of the first follow-up, there was a reduction in the number of subjects still requiring medication, with a significant reduction in FEV1, and a PC20 less than or equal to 16 mg/ml. However, no further change was observed afterwards. Similarly, the mean FEV1 and FEV1/FVC improved significantly from the time of diagnosis to the first follow-up (p less than 0.01), with a plateau thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Acute exposure to sawdust does not alter airway calibre and responsiveness to histamine in asthmatic subjects.

We investigated the effects of particles of sawdust delivered through a special device at known concentrations (close to the threshold limit value-short term exposure limit (TLV-STEL) of 10 mg.m-3) on FEV1 and PC20 in 12 asthmatic subjects free of clinical sensitization to this product. Subjects were studied over two days (day 1: exposure to sawdust; day 2: sham exposure) in random order with a maximum interval of 1 week. On each day, after the assessment of spirometry and PC20, subjects underwent exposure to sawdust or sham exposure. Sawdust was inhaled for a total of 30 min at average concentrations varying from 8.0 to 19.3 mg.m-3 (mean = 11.5 mg.m-3). Twenty-five to 39.7% (mean = 34.6%) of inhaled particles had a diameter less than 10 mu (diameter allowing deposition in the trachea and lower respiratory tract). At the end of each period of exposure, FEV1 was assessed. After recovery, the second PC20 was obtained. Serial measurements of FEV1 were carried out every hour for up to 6 h after the end of exposure. At that time, PC20 was reassessed. Only one subject showed an acute bronchoconstriction immediately after exposure to sawdust (maximum fall of 14% in FEV1) with complete recovery 10 min later. Overall, inhalation of sawdust did not modify PC20 by comparing the mean result of the first test with the second and the third assessments. Also, the mean changes in PC20 at each interval after exposure to sawdust were not significantly different from the variations in PC20 on the sham day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Bronchoconstriction due to exercise combined with cold air inhalation does not generally influence bronchial responsiveness to inhaled histamine in asthmatic subjects.

We investigated immediate and late changes in airway responsiveness to histamine, after bronchoconstriction due to exercise combined with inhalation of cold air, in ten asthmatic subjects who came on six days. On the first visit, the provocation concentration producing 20% fall in FEV1 (PC20) histamine was obtained. After functional recovery, each subject walked on a treadmill whilst breathing dry, cold air. This resulted in an immediate fall greater than 15% (mean +/- SD = 31.9 +/- 11.0%) in forced expiratory volume in one second (FEV1). Following recovery, PC20 was measured again. FEV1 was then monitored for up to 6-8 h. PC20 was measured then and on the two following days at the same time of the day. Subjects were studied on three control days using the same design except that a resting period replaced the exercise with cold air. The mean changes in PC20 at each interval after exercise combined with cold air were not statistically significant. Physiologically significant changes were obtained in only two subjects, reaching a maximum 8 h after the manoeuvre. In these subjects, changes in PC20 were reproducible during a second series of visits. It is concluded that bronchial responsiveness to histamine is not generally influenced by the bronchoconstriction due to exercise combined with cold air.

Adolescent↗

PubMed1988

Kinetics of the recovery from bronchial obstruction due to hyperventilation of cold air in asthmatic subjects.

The timecourse of recovery from bronchial obstruction due to inhaled cold air was studied in eight adult asthmatic subjects. On the first visit, bronchial responsiveness to inhaled histamine was assessed. On the other two visits, after assessment of baseline lung resistance (RL) and spirometry, dry cold (-20 degrees C) air was inhaled for three minutes. RL was monitored continuously until its return to baseline +/- 20%. The baseline concentration of histamine causing a 20% fall in FEV1 (PC20) varied from 0.03 to 5.9 mg.ml-1. The mean maximum increase in RL was 2-fold (2.03 +/- 0.41) and was reached 2-11 min after the challenge. RL values were linearly correlated to time (r2 values greater than 0.80 in 14/16 instances). The two slopes of recovery were not significantly different. Slopes of recovery and total time of recovery (14-55 min) varied greatly between subjects. No relationship was found between baseline airway calibre, bronchial hyperresponsiveness and maximal increase in baseline RL on the one hand and the slopes of recovery on the other.

Adult↗

PubMed1987

Occupational asthma in nurses handling psyllium.

Five nurses aged 31-55 years old had a history of asthmatic symptoms after being exposed to psyllium that they prepared and distributed to patients. They had been nurses for 9-20 years and had reported asthmatic symptoms related to work in the past 3-12 months. They reported symptoms of rhinoconjunctivitis and all were atopic but only one had a previous history of asthma. Four of the five tested subjects had an immediate skin reaction to a commercial psyllium extract. All had IgE antibodies to psyllium. At the time that they were investigated, four out of the five had a significant increase in bronchial responsiveness to methacholine (PC 20 less than 8 mg/ml). Inhalation challenges with psyllium caused isolated immediate (one subject) and dual reactions (three subjects). One subject exposed for only 1 min to the psyllium powder experienced a severe immediate bronchospastic reaction, which required intubation for 3 h with complete functional recovery thereafter. This experience illustrates the precautions necessary, with the inclusion of a cautious dose-response approach, even with an 'occupation-type' challenge in the laboratory.

Adult↗

PubMed1987

Shape of the dose-response curve to cold air inhalation in normal and asthmatic subjects.

Inhalation of cold air at increasing levels of minute ventilation with assessment of bronchomotor tone between each inhalation (dose-response curve) has been used as a method to assess bronchial hyperresponsiveness. However, no information is available on the shape of the obtained dose-response curve, and it is not known if a plateau of response is reached. We investigated this problem in 13 adult asthmatic subjects (PC20 methacholine results varying from 0.04 to 15.2 mg/ml), 5 normal and 2 former asthmatic individuals (PC20 greater than 8 mg/ml). Inhalation dose-response curves were drawn by asking the subjects to inhale dry cold air (-20 degrees C) for 3 min at progressively increasing degrees of ventilation (5, 10, 15, 20, etc., L/min) until maximal voluntary ventilation (MVV) or sufficient bronchoconstriction was reached. FEV1 was assessed after each degree until no further decline was seen. No functional recovery was observed before asking the subject to inhale the next dose of cold air. Maximal falls in FEV1 ranged from 20.7 to 56.5% in the current asthmatic subjects, whereas no significant (less than 10%) changes in FEV1 were obtained in the normal and former asthmatic individuals. Seven to 13 points on the individual dose-response curves were obtained for each current asthmatic subject. Curves were analyzed using the common pharmacologic logistic model. The coefficients of correlation were, in general, highly statistically significant. Curves obtained for the current asthmatic subjects represented a truncated sigmoidal pattern without a plateau. Curves were flat in the normal and former asthmatic individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Occupational asthma and IgE sensitization in a pharmaceutical company processing psyllium.

We assessed the prevalence of occupational asthma and IgE sensitization to psyllium in a pharmaceutical company producing psyllium hydrophilic mucilloid, which is used as a laxative. Workers were intermittently exposed, approximately 5 times/yr, for periods of less than 10 days. Of the 140 employees, 130 (93%) were studied before a processing period via a questionnaire spirometry (n = 125), blood sampling (n = 118), and skin prick tests (n = 120) with 7 common inhaled allergens as well as plantain and psyllium. Thirty-nine workers had a history suggestive of occupational asthma. Twenty-three of 120 (19%) showed a skin wheal diameter greater than or equal to 3 mm to psyllium and 31 of 118 (26%) had increased specific IgE antibodies; 39 (32%) workers had at least 1 of these 2 features. Subjects with a questionnaire suggestive of asthma or occupational asthma were further investigated by serial monitoring of peak expiratory flow rates and PC20 methacholine before and during the psyllium processing period. All workers had spirometry repeated during the processing period. Twenty-one subjects who had a PC20 less than or equal to 16 mg/ml (n = 10) and/or decreased their PC20 by a greater than or equal to 3.2-fold difference (n = 4) and/or changed their FEV1 by greater than or equal to 10% (n = 13) during the processing period were referred for inhalation challenges to psyllium in the laboratory. Five of the 18 workers for whom these tests were feasible gave an immediate bronchoconstrictive reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Occupational asthma due to fumes of galvanized metal.

Two solderers exposed to fumes of galvanized metal reported a history of shortness of breath and fever which occurred during the evening and night of days spent at work. Specific inhalation challenges performed by asking subjects to do soldering on galvanized iron revealed a late bronchospastic reaction. One subject also demonstrated a significant increase in oral temperature and peripheral neutrophils. Environmental measurements revealed the presence of zinc after soldering on galvanized metal. This contaminant was not present after a control exposure while soldering on iron. Although metal fume fever has been described in workers exposed to fumes of galvanized metal, this is the first account of occupational asthma due to this agent.

Asthma↗

PubMed1987

Prevalence of occupational asthma in spray painters exposed to several types of isocyanates, including polymethylene polyphenylisocyanate.

The prevalence of occupational asthma was assessed in four paint shops of a large assembly plant where 51 employees were exposed to several types of isocyanates, including polymethylene polyphenylisocyanate (PPI). Three employees were first referred by their physician for asthma symptoms. A questionnaire was administered to the other 48 employees. Seven of these were suspected of having work-related asthma. Airway hyperexcitability to inhaled histamine was demonstrated in these ten subjects (three referred and seven screened). The diagnosis of occupational asthma was confirmed in six subjects (three referred and three screened) through specific inhalation challenges in the laboratory to a paint system component containing PPI. Thus, the prevalence of occupational asthma was 11.8% in these paint shops using several types of isocyanates, including PPI.

Adult↗

PubMed1986

Within- and between-day reproducibility of isocapnic cold air challenges in subjects with asthma.

Eight adult subjects with asthma had isocapnic cold air challenges on 4 different days. Three consecutive tests were performed on each visit with functional recovery between tests. Subjects were asked to breathe dry cold air (-20 degrees C) for progressively increasing levels of minute ventilation (7.5, 15, 30, and 60 L/min and maximal voluntary ventilation) until a 20% fall in FEV1 had been reached or when maximal voluntary ventilation was done. FEV1 was assessed between each level. The doses of respiratory heat exchange and minute ventilation causing 10%, 15%, and 20% changes in FEV1 were interpolated from dose-response curves. The within- and between-day 95% confidence intervals based on a single determination on the loge scale varied from +/- 0.32 to 0.59 for the indices derived from respiratory heat exchange. Reproducibility of the between-day results was more satisfactory than for the corresponding within-day assessments. No significant within-day tachyphylaxis was demonstrated for these indices.

Adolescent↗

PubMed1986

Occupational asthma in sawmills of eastern Canada and United States.

Eleven individuals with a history of work-related asthma are described. They were employed in 10 different sawmills of northwestern and southeastern Quebec and Maine where coniferous trees (spruces, firs, and pines) are cut into boards. Duration of exposure and symptomatology varied from 1.5 to 40 years and 0.5 to 10 years, respectively. Ten subjects were atopic and seven demonstrated immediate skin reactivity to mixed tree pollens. The diagnosis of occupational asthma was confirmed by significant and sustained changes in serial peak expiratory flow rates at work as compared with a period off work in every individual and significant changes in bronchial responsiveness to histamine at work as compared with a period off work in eight individuals or significant changes in FEV1 at work in the three other subjects. Specific inhalation tests by exposing four workers to sawdust in our laboratory were negative. We conclude that working in this specific type of sawmills of eastern Canada and northeastern United States can cause occupational asthma. Although the causative agent is unknown, the presence of atopy and/or immediate skin reactivity to tree pollens and/or bronchial hyperresponsiveness might be risk factors.

Adult↗

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

Exposure to a sensitizing occupational agent can cause a long-lasting increase in bronchial responsiveness to histamine in the absence of significant changes in airway caliber.

A 58-year-old subject with a history of occupational asthma to red-cedar sawdust underwent specific inhalation challenges with this product. Significant increases in airway responsiveness to histamine (tenfold fall in PC20 FEV1) were documented 7 hours after exposure for 5 minutes to red cedar while baseline spirometry remained unchanged. A dual asthmatic reaction was induced during the following days by exposing the subject to red-cedar sawdust for 30 minutes and plicatic acid for 7 minutes. After recovery of PC20, the subject was reexposed to plicatic acid for 15 and 30 seconds on 2 consecutive days. No significant changes in FEV1, forced vital capacity, and residual volume were demonstrated in the following 8 hours, although minimal changes in forced expiratory flow rate between 25% and 75% of FVC were observed. PC20 dropped significantly and required 2 weeks to recover. This example illustrates that bronchial hyperresponsiveness to histamine can precede the changes in airway caliber after an antigen challenge. It also demonstrates that such changes can persist for up to 2 weeks after the challenge, even when no significant changes in FEV1 are induced.

Airway Resistance↗

PubMed1986

Theophylline partially inhibits bronchoconstriction caused by inhaled histamine in subjects with asthma.

Sixteen adult subjects in a clinical steady state had four consecutive histamine inhalation tests on the same day when they were not receiving oral theophylline medication. The provocative concentration of histamine causing a 20% fall in FEV1 (PC20) was used to assess the response. They were then administered active or placebo sustained-release theophylline preparations according to a double-blind, randomized 4.4.1. two-treatment crossover design. Medication was administered for a minimum of 3 consecutive days, and PC20 was reassessed on 4 different days, 3 to 4 hours after receiving active or placebo medication (two visits for each medication). A significant but small bronchodilator and blocking effect on histamine excitability was demonstrated for the active medication. This latter effect was present even by adjusting for changes in baseline airway caliber and for the intraindividual variability of the four PC20 values obtained on day 1. We conclude that theophylline partially blocks bronchial responsiveness to inhaled histamine.

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↗

PubMed1986

IgE sensitization in snow crab-processing workers.

Occupational asthma is a highly prevalent disease among snow crab-processing workers, but its immunologic mechanism has not been identified. Prick skin tests with snow crab-meat extract, commercial extracts from other crab genera, and snow crab cooking water collected in 1984 were performed on 119 workers. Crab-specific IgE was assessed by RAST in sera from 115 workers with meat and water extracts. Both skin and RAST tests were performed in 58 individuals. Diagnosis of occupational asthma had previously been confirmed in 54 individuals. A highly significant relationship was demonstrated between the presence of immediate skin reactivity or increased serum levels of specific IgE to crab extracts and the occurrence of occupational asthma. There was good agreement between the results of skin and RAST tests with extracts of either meat or snow crab cooking water. Cooking water and snow crab-meat extracts were more sensitive than commercial preparations. Water extract was more potent and more sensitive than meat extract. We conclude that there is evidence that occupational asthma in snow crab-processing workers is mediated through an IgE mechanism.

Aerosols↗

PubMed1986

Cold air inhalation has a cumulative bronchospastic effect when inhaled in consecutive doses for progressively increasing degrees of ventilation.

In 12 asthmatic subjects, we compared the bronchoconstriction obtained with 3 methods of isocapnic inhalation of cold dry air (IICDA) on 6 visits, two visits for each method: Dose-response curves (DRC), which were obtained by asking the subjects to inhale at progressively increasing degrees of ventilation (7.5, 15, 30, 60 L/min and maximal voluntary ventilation [MVV] at a fixed breathing rate); free MVV, i.e., breathing frequency not set; same degree of ventilation as the last required for DRC (VEeq). Degrees of ventilation were significantly greater with the free MVV method. The percentage fall in FEV1 obtained by VEeq method was significantly lower than the changes recorded with the DRC and the MVV methods, the 2 latter being not significantly different. We conclude that IICDA induces a cumulative bronchoconstriction by the DRC method. However, the bronchoconstriction obtained with the latter method is not significantly different from the one obtained with the free MVV method.

Asthma↗