European journal of respiratory diseases. Supplement最新文献

The lipid composition of airway secretion is described. Major differences in the literature may depend on methods. Bronchoalveolar lavage includes a major contribution of alveolar surfactant. Sputum may be contaminated by secretions from the upper airways and saliva, and shows great variations in total lipids and free fatty acids. Diseases affect its composition. Tracheobronchial aspirates and washings are more direct methods and show much cholesterol, DPPC, and other phospholipids. Secretions by explants and cell cultures also show very mixed lipid composition including neutral, phospho- and other lipids. Although much airway lipid may travel up from the alveoli, there is evidence that the larger airways can secrete their own lipids. They may also arise from breakdown of cells. Their functions may include a modification of mucus rheology, an effect on ciliary beat and mucociliary clearance, a modification of mucus adhesiveness, an action on bacterial invasion, and a lessening of the tendency to collapse of small airways due to the surface activity of the lipids.

An overview of activities of the EORTC Lung Cancer Coöperative Group in small cell lung cancer is given. Optimal length of therapy, identification of patients with good/bad prognostic factors, role of surgery and the study of new drugs presently are the main areas of interest for the group. With its large patient potential the group is able to verify "early favourable reports" and to quickly perform phase II studies.

We examined the relationship between mucus rheology, depth of mucus layer, and clearance by simulated cough. A model trachea constructed of rigid plexiglass was lined with mucus simulants--borate-crosslinked locust bean gum gels. Their viscoelastic properties were determined by magnetic rheometry and expressed as mechanical impedance (dynamic stress/strain ratio or vectorial sum of elasticity and viscosity) and loss tangent (viscosity/elasticity ratio). Cough was simulated by opening a solenoid valve connecting the model trachea to a pressurized tank, using an upstream flow-constrictive element to shape the flow profile to approximate the pattern seen in a normal adult. Mucus clearance was quantitated by observing the movement of contrasting marker particles placed in the mucus layer. The median particle displacement per cough manoeuvre was defined as the clearance index, C.I. We found that C.I., for any initial depth of mucus, increased with the driving pressure in the tank. For a given driving pressure, C.I. increased linearly with increasing mucus depth. For a given driving pressure and depth, C.I. decreased with increasing mechanical impedance of mucus. At constant mechanical impedance, C.I. increased with increasing loss tangent. Mucus clearance was associated with transient wave formation in the lining layer. Thus the dependence on viscoelasticity is consistent with the observations that airflow-mucus interaction and wave formation are impeded by elasticity. The clearance vs. loss tangent relationship for cough is opposite to that found for ciliary clearance, suggesting a natural balance in viscosity and elasticity for mucus to be cleared by both mechanisms.

It has been demonstrated that compression and expansion of a monomolecular film lead to a unidirectional transport of particles which are present on this film. Using the same model we could demonstrate that Broncho-Alveolar Lavage fluids from healthy rats also produce a transport of particles in the direction of the compression phase and that lavage fluids from SO2 exposed rats show impaired and even reversed transport properties. In parallel there is a change of the phospholipid pattern in lavage fluid from SO2 exposed animals. The relevance of these observations is discussed for physiological and pathophysiological situations in the lung periphery.

Airway mucus is essential for the effectiveness of cough and mucociliary transport. Even the resting airway produces some mucus but, under a great variety of threats to airway function, this production increases. A number of mechanisms may be responsible for augmenting secretion; these include reflexes, initiated by nervous receptors in the airways, and with their efferent limbs in the autonomic nerves to the airways. Cigarette smoke short circuits this reflex pathway; nicotine absorbed from the smoke stimulates ganglion cells directly and so drives secretion. Secretomotor nerves which control the output from submucosal glands include cholinergic, adrenergic and NANC fibres. A number of mediators of the sort released during inflammation and antigen challenge, including prostaglandins and leukotrienes, can also elicit secretion into the airway lumen. Other stimuli act at least partly on unknown mechanisms to release mucus from the surface epithelium into the airway lumen. For example inhalation of dust, which stimulates cough receptors and so acts partly by driving mucus secretion reflexly, also initiates secretion into the denervated airway. Similarly, during the inhalation of cool dry air, the airway lining secretes more mucus, probably by a non-nervous mechanism which responds to drying of the airway surface. More needs to be learned about such apparently direct mechanisms. Different control systems appear to stimulate the production of a variety of mucins from distinct cell types. We do not yet know the physiological and pathological importance of these differences.

Seventeen victims of farmer's lung were monitored during two indoor feeding seasons for cattle. The victims, who had all recovered from the acute phase of the disease before entering the experiment, used powered helmets for respiratory protection (Air-Stream) equipped with Type P2 filters. Filters were changed once a week. The lung function of each subject was investigated at the beginning and towards the end of the indoor feeding season. Each subject kept a diary about the use of dust respirators, changing of filters, inconvenience related to the use of respirators, and symptoms experienced during the follow-up. None of the subjects reported symptoms they related to farmer's lung, and mean values for the lung function parameters (PEF, FEV1, FVC, DLCO, and KCO) did not decrease during the two follow-up periods. In contrast, mean DLCO and KCO increased slightly. At the very end of the both indoor feeding seasons, after the actual follow-up periods, one subject developed mild recurrences of the disease without deterioration detectable by radiology. The patient asserted that he had used the protective helmet properly. The results indicate that powered respirator helmets have protective value in farmer's lung and are appropriate for long-term use. A possibility remains, however, that the disease may recur in highly sensitized individuals, despite the use of efficient protective devices. Other measures for preventing or decreasing mould exposure are equally important.