Nouveaux outils d’évaluation du contrôle de l’asthme : le NO expiré et le NO nasal

Nitric oxide (NO) is present in the upper and lower human airways. Nasal and exhaled levels of NO can be determined by non-invasive techniques using chemiluminescence analysers. NO levels in the upper airways are 10–100-fold higher than in the lower airways. International recommendations for standardized measurement of nasal and exhaled NO have been published recently. Exhaled NO is increased in patients with untreated asthma, and this elevation reflects, at least partially, bronchial inflammation. Measurement of exhaled NO may be useful when the diagnosis is doubtfull and for differentiation from other causes of chronic cough. Nasal NO is usually also increased in asthma but this is related to the frequency of allergic rhinitis in asthmatic patients. However, in patients with nasal polyps and asthma, nasal NO is decreased in proportion to the extent of sinusoidal involvement. Levels of exhaled NO decrease rapidly in asthmatic patients treated with anti-inflammatory drugs. Further studies are needed to establish more precisely the place of exhaled NO measurement in monitoring the control of asthma, especially in comparison with other non-invasive markers of bronchial inflammation.     

Faim et satiété, contrôle de la prise alimentaire

Food intake is a complex periodical behaviour through which a living organism can extract vital nutrient and energy substances from the environment. Hunger and satiety are psycho-physiological states that, respectively, elicit or inhibit food intake. Homeostatic (glucostatic or lipostatic) and non-homeostatic (environmental conditions) mechanisms contribute to the periodic initiation of food intake. Once a meal has started, the stimulation to eat is progressively antagonized by the cumulative effects of the ingested foods. This satiation process brings the eating episode to an end before the ingested nutrients have been absorbed. Meal size is determined by an interaction of sensory (food quality and variety), gastro-intestinal, and neuroendocrine responses. A Pavlovian learning mechanism allows the metabolic consequences of ingesting a particular food to become associated with the sensory characteristics of the food; as a consequence, a unique repertoire of food acceptance and rejection responses is shaped for each individual eater. Satiety, the post-meal phase of inhibition of eating, depends on the nutrient composition of the meal and, mainly, on its energy density. The selection of high energy-density foods induces little satiety and favours “passive over-consumption”. In humans, culture, socio-economical status, family context, and even the physical characteristics of the environment affect food choices and energy intake. The mechanisms selected by Evolution in order to allow survival under environmental conditions of food shortage seem more efficient at correcting for energy needs than excesses. In the present context of food plethora, the obesity epidemic reflects both a biological bias and the potent stimulation from the environment.     

Réaction anaphylactoïde post-BCG : le rôle du dextran ?

The authors describe the case of a 16-year-old male without any medical history who developed anaphylactic shock a few minutes after the injection of the intradermal vaccine BCG Pasteur. Chronology of events, lack of any other drug intake and the dramatic increase of serum tryptase level account for the anaphylactic reaction consecutive to vaccine injection. A few weeks after the accident, the allergic data donˈt reveal much. At this time, serum anti dextran IgG are significantly high (8 mg/L), suggesting the involvement of dextran in this severe adverse reaction.