Biomedical subjects
D Vervloet
Publications and source records attributed to D Vervloet.
Effects of a constant dose rate of terbutaline on circadian peak expiratory flow, heart rate and systolic arterial pressure in patients with asthma exacerbation.
The purpose of this study was to investigate the effect of a constant infusion rate of terbutaline on circadian bronchial peak expiratory flow rate (PEFR), heart rate and arterial pressure in patients with asthma exacerbation. Fifteen hospitalized asthmatic patients (6 females and 9 males, mean age 43.3 years, mean weight 67.0 kg) were included in this study. In order to reach the desired plasma concentrations of terbutaline immediately, a pharmacokinetic simulation was done. Based on the predicted values thus obtained, an initial 5-min bolus dose of 2.94 micrograms/kg was given to all patients at 7 a.m., i.e. at the beginning of the study. Over the following 24 h (7 a.m. to 7 a.m.), 33 micrograms/kg of terbutaline was infused intravenously at a constant rate with an electric pump. Since severe acute asthma requires corticosteroids, a 40-mg injection of methylprednisolone was given to all patients at 7 a.m. PEFR, heart rate, systolic arterial pressure, side effects and plasma terbutaline levels were recorded at 7 and 10 a.m., 1, 4, 7 and 11 p.m., and 3 and 7 a.m. the following morning. Terbutaline had a significant favorable effect on asthma exacerbation but no circadian rhythm was found in PEFR. Although terbutaline was infused at a constant rate, plasma levels depended on circadian variations.
Mechanisms of anaphylactic reactions to muscle relaxants: role of allergenic determinants.
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[Clinical effectiveness and tolerance of loratadine versus cetirizine in the treatment of seasonal allergic rhinitis].
A double blind multicentre study of seasonal rhinitis (108 patients) has compared Loratadine and Cetirizine. The results of clinical scores are significantly good for both products. Only tolerance is different and in favour of Loratadine, since sleepiness was found in 9.5% of patients treated with Cetirizine, and 3.6% with Loratadine.
Fel d I allergen: skin and or saliva?
To determine the relative importance of saliva and sebaceous glands as sources of Fel d I allergen, we compared Fel d I levels at the base and tip of the hair in areas presenting more or less sebaceous glands and areas licked more or less frequently. The amount of Fel d I was significantly higher at the base than the tip of the hair. Further, it was strongly correlated with the density of sebaceous glands. This study demonstrated that the most abundant source of Fel d I allergen is cat skin.
[Spatial and temporal variations of the quantities of pollen from Cupressaceae-Taxaceae collected in Marseilles].
Marseille has two sites (Centre and North) where airborne pollens are collected and counted. The most numerous pollens are from Cupressaceae Taxaceae. We compared the quantities collected with both pollen traps during February, March and April 1988 and 1989. Most of pollinization takes place in March. In Marseille's Centre, there were three times more trapped pollen during 1989 than in 1988. In 1989, there was 40% more pollen on northern site as compared with the other one. As indicated in 1989 with both sites, it suggests a circadian periodicity of Cupressaceae Taxaceae pollen: their highest count is usually between 9 and 11 hours a.m.
[Evaluation of asthma: clinical or functional scores?].
This article is a review of the clinical and functional scores used for the assessment of the severity of asthma. Dyspnea is a key feature of asthma but its severity is difficult to interpret. Subjects with continuous airway obstruction may tend to be poor sensors of their dyspnea. The addition of other symptoms such as cough, wheezing, etc. to the dyspnea score can also be criticized. An international consensus conference recently proposed a clinical and functional scale to assess the severity of asthma. A combination of clinical, drug and functional information can best express the severity of asthma. Data originating from the authors work suggest that the correlations between clinical and drug scores on the one hand and peak expiratory flow rate values on the other hand are weak. It is the authors' final impression that the severity of asthma should be judged in a global way by considering various parameters.
Cat removal and Fel d I levels in mattresses.
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Cross-reactivity between latex and banana.
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Comparison of the ACAREX test with monoclonal antibodies for the quantification of mite allergens.
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Fel d I allergen distribution in cat fur and skin.
Immunohistochemical procedures were performed to ascertain Fel d I antigen (Ag) distribution in cat fur and skin biopsy specimens and to analyze Fel d I allergen concentrations in fur. One hundred strands of fur and 24 skin biopsy specimens (6 by 4 by 3 mm) from shaved areas were collected from 11 different cats. Freshly depilated hairs were immunostained by free-floating monoclonal anti-Fel d I, avidin-biotin-peroxidase complex, and either processed for scanning electron microscopic examination or mounted on glass slides for computer-assisted densitometric analysis (SAMBA system). Skin biopsy specimens were promptly frozen and sectioned just before the immunohistochemical processing. Densitometric analysis of fur demonstrated that immunoprecipitate concentrations were tenfold higher at the root than at the tip. However, this finding may be explained by decrease of the thickness of the hair cortex that varied in similar proportions. The Ag accumulated on the strand surface but may focally penetrate into the medulla through the scale-like cortical interstices. In skin biopsy specimens, Fel d I Ag was found in epithelial squamous cells, within the epidermis and hair follicles, on the surface of the epidermis and hair follicles, and in sebaceous gland cells. These data suggest that Fel d I Ag is produced by sebaceous cells and, to a lesser extent, by basal squamous epithelial cells and that it is stored mainly on the surface of the epidermis and fur.
Reliability of respiratory symptoms to diagnose atopy.
As reliance of responses to epidemiological questionnaires on atopic symptoms is doubtful, we studied the predictive value of these questions relative to atopy, defined by the presence of serum specific IgE, taking into account some extraneous variables such as age and sex. The study population included 2067 adults, 20-60 years old. The protocol consisted of a standardized questionnaire and an evaluation of serum specific IgE using the Phadiatop (Pharmacia Diagnostics, Uppsala, Sweden) test. The predictive value of each symptom suggestive of atopy was quite low, but was much dependent on age and sex. Women more often than men reported atopic symptoms in the absence of atopy. Similarly, the predictive value of each symptom decreased with age. Thus atopic symptoms do not have the same value as predictors of atopy. These findings have both clinical and epidemiological important implications.
Is intrinsic asthma a hereditary disease?
Although studies of families, inbred populations and twins have established that asthma has a hereditary basis, little evidence has shown that intrinsic asthma has an increased familial occurrence. To document this issue, we compared the prevalence of asthma in families of intrinsic asthmatics, extrinsic asthmatics and non-asthmatics. The intrinsic asthma group included those with negative skin tests to common aero-allergens (n = 117). The extrinsic asthma group included those with one or more positive skin tests (n = 164). The non-asthmatic group (n = 224) was recruited at a check-up center. The siblings of each subject completed a standardized questionnaire on history of asthma. The results showed that asthma was more prevalent (P less than 0.001) in siblings of intrinsic asthmatics (8.9%) than in siblings of the non-asthmatic group (2.4%). The prevalence of asthma in siblings of intrinsic and extrinsic asthmatics was similar. In conclusion, both intrinsic and extrinsic asthma have an increased family occurrence.
Medication requirements and house dust mite exposure in mite-sensitive asthmatics.
To better understand the clinical consequences of exposure to house dust mites (HDM), we investigated the relationship between treatment requirements to control symptoms in mite-allergic asthmatic patients and HDM-allergenic levels in their mattresses. This study included 49 asthmatic subjects recruited from an outpatient clinic. The protocol consisted of a questionnaire about the number of asthma attacks and treatment requirements in the last 3 months. Patients provided a sample of house dust collected from their mattresses by a standardized vacuum cleaning procedure. Mean antigen P1 equivalent defined as the sum of major allergens Der pI and Der fI (Ag P1 Eq) level was 1.34 micrograms/g dust in patients who had no treatment, 5.4 micrograms/g dust in patients who took puffs of beta 2-agonists only when required and 17.8 micrograms/g dust in patients who required daily long-term treatment. Similar relationships were demonstrated between mean Ag P1 Eq levels and the number of asthma attacks. These data support the clinical role of allergenic exposure in HDM-allergic asthmatics.
Altitude and allergy to house-dust mites. A paradigm of the influence of environmental exposure on allergic sensitization.
To further investigate the possibility of a cause and effect relationship between exposure to house-dust mite (HDM) allergens and respiratory disease associated with dust mite sensitivity, we compared schoolchildren living in the Alps, where exposure to HDM is low, with those living at sea level, where it is high. The study included 933 schoolchildren from the fourth and fifth grades. The protocol included the standardized 1978 American Thoracic Society (ATS) questionnaire for children, skin testing using common aero-allergens and controls, and antigenic measurements of dust samples from mattresses (Group I antigen). The prevalence of asthma with positive skin test to HDM and the overall prevalence of positive skin test to HDM were significantly lower in mountain schoolchildren. The mean geometric HDM antigenic level in mattresses was much lower in the Alps (0.36 micrograms/g dust) than at sea level (15.8 micrograms/g dust). In contrast, the prevalence of hay fever and positive skin test to grass pollens as well as the overall prevalence of positive skin tests to grass pollens were significantly higher in the Alps. These data illustrate a striking relationship between exposure to environmental allergens and atopic sensitization.
Unequal day-night terbutaline i.v. dosing in acute severe asthma: effect on nocturnal bronchial patency, heart rate, and arterial pressure.
Our study investigated the differential effects of continuous or unequal day-night terbutaline dosing on circadian bronchial patency, heart rate, and arterial pressure in severe acute asthma. Forty-five hospitalized asthmatic patients (19 women and 26 men, mean age 45.4 years, mean weight 63.5 kg) were included in this multicenter study. Three groups of patients (corresponding to three dosing schedules) were randomized; the three groups were comparable, since no statistically significant difference was detected in the age, weight, or peak expiratory flow values at the beginning of the study. In order to reach immediately the concentrations of terbutaline corresponding to the desired unequal day-night concentrations, a theoretical pharmacokinetic simulation was done to predict the outcome in terms of the plasma concentrations after the three dosing regimens; the results of this simulation allowed us to calculate the initial bolus dose to be given over 5 min to groups A, B, and C, i.e., 1.47, 2.94, and 4.41 micrograms/kg, respectively. This bolus was given to all patients at 0700 h, the beginning of the study.(ABSTRACT TRUNCATED AT 250 WORDS)
Rat basophilic leukemia cells: protein kinase C and secretion.
Phorbol myristate acetate (PMA) but not its inactive analogue phorbol didecanoate modulated the release of [3H] serotonin by rat basophilic leukemia (RBL) cells stimulated by antigen-IgE complexes. Concanavalin A or the calcium ionophore ionomycin, suggesting that protein kinase C (PKC) was involved in the exocytosis process. The PKC inhibitor sphingosine markedly inhibited release. When the PKC content of RBL cells was diminished by a prior 24 h-exposure (long-term PMA-treated cells) to 50 or 100 ng/ml PMA, the release induced by the three secretagogues was also strongly inhibited. Since cell activation by PMA in different cell systems is accompanied by PKC translocation from cytosol to membrane, we studied the location of PKC in resting cells and its translocation by a 5 min-exposure to 100 ng/ml PMA. PKC was cytosolic in long-term PMA-treated and control RBL cells and its translocation occurred regardless of the total PKC cell content, showing a possible correlation between the level of functional PKC (susceptible to be translocated) and exocytosis. Taken together, these data suggest that PKC is involved in the controlling of exocytosis by different secretagogues.