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Biomedical subjects

C Mapp

Publications and source records attributed to C Mapp.

At least 19 recordsLinked to original sources
PubMed1990

Venous blood platelets decrease during allergen-induced asthmatic reactions.

To determine whether circulating platelets alter during asthmatic reactions induced by allergens, we studied nine subjects previously shown to develop an early or dual asthmatic reaction after inhalation challenge with extracts of house dust mite or grass pollen. In each subject, FEV1, circulating platelets and leucocytes were measured before, 15, 30 and 60 min, and 2, 4, 6 and 8 hr after inhalation of allergen and diluent control administered in a single-blind, randomized fashion. The same procedure was repeated in six of the nine subjects after bronchoconstriction induced by methacholine. Each subject developed an early asthmatic reaction after allergen inhalation challenge, which was followed by a late asthmatic reaction in six subjects and by an equivocal late asthmatic reaction in two of them (fall in FEV1 of 15 and 17% respectively). Compared with the control day, circulating platelets significantly decreased during the allergen-induced early asthmatic reaction (P less than 0.025, at 30 min). Platelet counts returned to baseline values within 4 hr and remained steady thereafter both in subjects who did and did not develop a late asthmatic reaction. No changes in platelet counts occurred after bronchoconstriction induced by methacholine. Diurnal increase of leucocyte numbers occurred after challenge with both allergen and diluent control. These results suggest that platelets may be involved in the pathogenesis of allergen-induced asthmatic reactions.

Adolescent↗
PubMed1989

Ambroxol inhibits airway hyperresponsiveness induced by ozone in dogs.

To follow up previous observations that airway hyperresponsiveness induced by ozone is linked to airway inflammation and particularly to the release of arachidonic acid metabolites, we investigated the effect of ambroxol (a mucoactive and surfactant-stimulating drug that has recently been discovered to inhibit the release of arachidonic acid from cell membrane phospholipids) on airway hyperresponsiveness and bronchoalveolar neutrophilia induced by ozone in dogs. One group of 5 dogs was studied before treatment with nebulized saline and then after exposure to ozone (3 ppm, 1 h); another group of 6 dogs was studied before treatment with ambroxol (100 breaths of a 1% solution) and after exposure to ozone. On each occasion, we measured airway responsiveness to acetylcholine and counted the number of cells in bronchoalveolar lavage fluid. When the dogs were given the saline placebo, ozone induced a marked increase in airway responsiveness to acetylcholine and a marked influx of neutrophils in the airways. When the dogs were given ambroxol, ozone induced the same increase in the number of neutrophils in bronchoalveolar lavage, but did not increase the degree of airway responsiveness to acetylcholine. We conclude that ambroxol inhibits ozone-induced airway hyperresponsiveness in dogs, probably by inhibiting the formation and release of oxygenation products of arachidonic acid from neutrophils.

Acetylcholine↗
PubMed1987

Protective effect of antiasthma drugs on late asthmatic reactions and increased airway responsiveness induced by toluene diisocyanate in sensitized subjects.

To determine whether 4 drugs used in the treatment of asthma inhibit the late asthmatic reaction and the associated increase in airway responsiveness induced by toluene diisocyanate (TDI), we studied 24 sensitized subjects divided into 4 groups. Beclomethasone aerosol (1 mg bid), slow-release theophylline (6.5 mg/kg bid), slow-release verapamil (120 mg bid), and cromolyn (20 mg qid via spinhaler), were administered for 7 days, respectively, to 1 of the 4 groups, according to a double-blind, crossover, placebo-controlled study design. When the subjects were treated with placebo, verapamil, or cromolyn, FEV1 markedly decreased and airway responsiveness increased after exposure to TDI. By contrast, beclomethasone prevented the late asthmatic reaction and the associated increase in airway responsiveness to methacholine induced by TDI. Slow-release theophylline partially inhibited both the immediate and the late asthmatic reactions but had no effect on airway hyperresponsiveness to methacholine. These results suggest that only high-dose inhaled steroids can completely block TDI-induced late asthmatic reactions.

Asthma↗
PubMed1986

Prostaglandin D2 (PGD2) potentiates cholinergic responsiveness in guinea-pig trachea.

PGD2 dose dependently potentiated the parasympathetic-induced contraction in guinea-pig trachea in vitro. This phenomenon was much more evident in ovalbumin-sensitized guinea-pig trachea. Indomethacin pretreatment enhanced the capacity of PGD2 to potentiate cholinergic-induced contraction in normal but not in ovalbumin-sensitized guinea-pig. PGD2 shifted to the left the curve of the exogenous acetylcholine-induced contraction in guinea-pig trachea, indicating a postsynaptic site of action of PGD2. These data suggest a role of PGD2 in the genesis of hyperreactivity of tracheal smooth muscles, particularly in a model of pulmonary anaphylaxis.

Acetylcholine↗
PubMed1986

Immunologic and nonimmunologic responsiveness in ragweed-sensitized dogs.

The relationship between airway responsiveness to inhaled antigen and histamine, immunologic release of lung histamine, immunologic responsiveness of skin, and specific immunoglobulin E (IgE) antibodies were examined in 11 inbred allergic dogs immunized with extracts of ragweed and grass and 5 nonimmunized control dogs from the same colony. Airway responsiveness to antigen and histamine was characterized by the doses that increased the airflow resistance of the total respiratory system to twice the control values (ED200). Highly significant correlations were found between airway responsiveness and cutaneous responsiveness to antigen and other immunologic characteristics (e.g., IgE and histamine released from lung by inhaled antigen) in all dogs. In ragweed-sensitized dogs, there was an inverse correlation between immunologic responsiveness (reflected by the cutaneous response to antigen and histamine released from lung by inhaled antigen) and nonimmunologic responsiveness of airways (histamine ED200: r = 0.73, P less than 0.05 and r = 0.75, P less than 0.01, respectively). Antigen ED200 was also correlated with histamine release from lung after antigen inhalation (r = 0.74; P less than 0.01). We conclude that airway reactions to inhaled antigen in allergic dogs are dependent not only on immunologic factors but also on the degree of nonimmunologic airway responsiveness to histamine and that these factors are correlated inversely.

Animals↗
PubMed1985

Nicotine-induced respiratory effects of cigarette smoke in dogs.

We report that nicotine is responsible for both a blood-borne stimulation of the respiratory center and a direct effect on intrathoracic airway tone in dogs. We introduced cigarette smoke into the lungs of donor dogs and injected arterial blood obtained from them into the circulation of recipient dogs to show that a blood-borne material increased breathing and airway smooth muscle tone. Smoke from cigarettes containing 2.64 mg of nicotine was effective; that from cigarettes containing 0.42 mg of nicotine was not. Nicotine, in doses comparable to the amounts absorbed from smoke, also increased breathing and tracheal smooth muscle tension when injected into the vertebral circulation of recipient dogs. Finally, blockade of nicotine receptors in the central nervous system and in the airway parasympathetic ganglia inhibited the effects of inhaled cigarette smoke and intravenous nicotine on the respiratory center and on bronchomotor tone. We conclude that nicotine absorbed from cigarette smoke is the main cause of cigarette smoke-induced bronchoconstriction. It caused central respiratory stimulation, resulting in increased breathing and airway smooth muscle tension, and had a direct effect on airway parasympathetic ganglia as well.

Animals↗
PubMed1985

Airway responsiveness to inhaled antigen, histamine, and methacholine in inbred, ragweed-sensitized dogs.

We studied the responses to antigen in animals selected from a colony of inbred dogs sensitized to specific allergens to determine if they had characteristics similar to those of human asthmatics. They were immunized with ragweed and grass pollen extracts (10 micrograms in alum) immediately after routine vaccination with attenuated live virus (distemper and hepatitis) and killed bacteria (Leptospira) at 4, 8, and 12 wk of age. Subsequently, ragweed and grass injections were repeated every 2 months. Immunized dogs made specific IgE-antibodies in serum averaging 3 to 4 times that of control animals (no immunization with pollen or vaccine). They showed positive skin responses to the injection of ragweed pollen extract, whereas control dogs did not respond to ragweed pollen by quantitative skin test or inhalation challenge. In immunized dogs under barbiturate anesthesia, air-flow resistance of the total respiratory system increased from 0.60 +/- 0.07 (mean +/- SEM) before to 12.6 +/- 3.4 cm H2O/lps 5 min after the start of antigen aerosol; respiratory resistance remained increased for 20 min and was associated with 0 hypoxemia and increased arterial plasma histamine. In addition, airway responsiveness to both inhaled histamine and methacholine was greater in immunized dogs than in nonimmunized dogs of comparable age. Airway responses to each agonist were highly reproducible on repeated testing. These results indicate that physiologic responses to antigen by inbred, ragweed-sensitized dogs resemble human asthma closely and that these dogs appear suitable for a variety of experimental studies of asthma with respect to pathogenesis, diagnosis, prevention, and treatment.

Animals↗
PubMed1977

[Chronic broncopneumopathy and pneumoconiosis in workers employed in phosphoric acid production (author's transl)].

Thirty-five subjects employed in a phosphoric acid producing plant were studied by the authors. The investigation included: history, according to the C.E.C.A. questionnaire for chronic bronchitis and emphysema; physical examination, chest X-ray spirometry and lung diffusing capacity for carbon monoxide by the steady state method (DLCOSS). High prevalence of chronic bronchitis (45.7%), obstructive spirometric impairment (37.1%), and decreased values of DlcoSS (31.4%) were detected. Two subjects were found to be affected with p 1/0 and 7 with p 0/1 pneumoconiosis. Such findings were significantly related to the lenght of working activity as well as to dust and gaseous fluoride (hydrofluoric acid, hexafluorosilicic acid and silicon tetrafluoride) exposure.

Adult↗
PubMed1976

[Epidemiologic evaluation of isocyanate immediate irritative action: 'one day effect' control (author's transl)].

Nineteen MDI exposed workers showed ventilatory changes, after eight hour exposure, mainly involving upper respiratory airways; the changes reversed following a bronchodilator aerosol. An incomplete recovery of VC was found in some subjects; therefore, the possibility of changes in the lung elastic recoil forces was hypothesized. No statistically significant differences were found as to occupation and smoking habit, which suggests that even low MDI concentrations could be enough to give rise to acute effects. The greater impairment found in subjects who were already affected by morning time emphasizes the necessity that such subjects were not employed in their specific work.

Adult↗