European journal of respiratory diseases. Supplement最新文献

This study was based on a sample of 3,065 farmers from a larger survey population of 12,056 Finnish farmers. Data were gathered in a postal survey conducted by the Social Insurance Institution of Finland. Serum precipitins were determined by a microplate method of immune diffusion. The antigen panel consisted of mycelial antigens of Micropolyspora faeni, Thermoactinomyces vulgaris, Aspergillus fumigatus, and Aspergillus umbrosus. Geographical variation in the prevalence of precipitins was statistically significant, evidently due to climatic differences. The more intensive the cattle raising, the more commonly were precipitins found in the sera of farmers. For participation in animal tending (cattle, pigs, or poultry) or in plant cultivation work only, the prevalence of precipitins was largest among farmers who tended cattle or swine. According to earlier studies, serum precipitins to Thermoactinomyces vulgaris are associated with farmer's lung. Precipitins to this microbe were most commonly found in farmers who tended pigs and were also very common in farmers who worked only in plant cultivation. These findings imply that farmer's lung may also develop among pig farmers and grain producers. Precipitins to Thermoactinomyces vulgaris were clearly related to the type of grain drier used on the farm. The study failed to identify detailed tasks in farming associated with large prevalence of precipitins, probably owing to considerable overlap in the exposure encountered in different tasks.

Development of chronic bronchitis has been shown to depend strongly on smoking habits. Atopy is known to predispose individuals to the development of asthma. Few studies, however, have dealt with the role of the atopic status of the individual as a predisposing factor for chronic bronchitis. In our previous survey among farmers, we observed that chronic bronchitis occurred more often among atopic than non-atopic subjects. Atopy was defined on the basis of past or present atopic manifestations. The association between atopy and chronic bronchitis was re-examined in a separate study of 169 individuals. Using the skin-prick technique we tested these farmers for atopy. The antigen panel included 36 common and farm-related allergens. Among non-smokers with negative skin tests the prevalence of chronic bronchitis was 5.6%, whereas among farmers with positive skin tests (area of at least one skin test reaction equal to 6 mm2 or larger) the prevalence of chronic bronchitis was 15.1%. When age, sex and smoking habits were accounted for statistically, individuals with positive skin tests suffered from chronic bronchitis twice as frequently as subjects with negative skin tests. The predisposing effects of smoking and atopy were of the same order of magnitude. The results of the clinical study of atopy correspond closely to those of the survey study. In the farming population, individuals with an atopic constitution are predisposed to development of chronic bronchitis.

Work-related respiratory diseases are common among farmers. Few studies, however, have dealt with the consequences of respiratory diseases for the lives of the afflicted farmers. To estimate the socioeconomic consequences of respiratory diseases in the farming population, we made a cross-sectional study and a follow-up study. In 1979 farmers with farmer's lung were twice as likely as healthy farmers to plan to reduce their farming work or to stop farming completely. Fifteen percent of the farmers who developed chronic bronchitis during a three-year follow-up had decided to reduce farming work, close down the farm or change the line of production on the farm. The respective rate for healthy farmers was 8%. In 1982, after the follow-up study of new cases of respiratory diseases, the rate of giving up occupational activities was twice as great among individuals with farmer's lung or asthma as in the rest of the farming population. Based on this study, we estimated that of the new cases of respiratory diseases, every tenth will stop farming in the near future, owing to one of the respiratory diseases analyzed. In Finland about 300 farmers per 100,000 and a total of about 600 farmers annually reduce their farming work or stop farming due to respiratory diseases.

A number of proteolytic enzymes (proteases) and their inhibitors (anti-proteases) have been demonstrated in the bronchial secretions. The most important of these proteases is probably the potent elastase derived from polymorphonuclear leukocytes (PMN) which are recruited into the bronchial tree during inflammation. This enzyme can degrade elastin, collagen and proteoglycan and can damage the bronchial epithelium; it is inhibited by antileukoprotease and by alpha protease inhibitor (API). Pulmonary macrophages also secrete an elastase, but Pseudomonas aeruginosa is the only microorganism known to produce elastase. Antileukoprotease is probably the most important of the antiproteases to be found in bronchial secretions. Other antiproteases such as low molecular weight inhibitors, API and alpha 2 macroglobulin have been demonstrated in bronchial secretions but they are present in low concentration. A balance between proteolytic enzymes and their inhibitors is thought to be of great importance in the prevention of proteolytic damage to local tissues, not only in emphysema but also in chronic bronchitis, bronchiectasis and cystic fibrosis. Oxidants derived from PMN or from tobacco smoke can inactivate protease inhibitors and in both the bronchial tree and the lung parenchyma, a balance between oxidants and anti-oxidants must presumably also be maintained to prevent local tissue damage.

Several recent reports have documented the efficacy of surfactants replacement therapy in the neonatal respiratory distress syndrome (RDS). The surfactants tested in these trials were obtained from animal lungs or human amniotic fluid. In general, such natural preparations seem to be superior to entirely synthetic surfactants, although promising results have recently been obtained in animal experiments with artificial surfactant based on isolated apoproteins and synthetic phospholipids. Furthermore, surfactant replacement therapy seems to be more effective when the exogenous material is administered at birth, before the first breath, than when surfactant is instilled into the airways after a period of ventilation. This discrepancy may be due to maldistribution of the exogenous material, or to the rapid development of epithelial lesions in the immature lung, with leakage of surfactant-inhibiting proteins into the airspaces. A transient beneficial response to surfactant replacement may also be due to circulatory problems, especially reversal of the shunt through a patent ductus arteriosus, with overloading of the lung circulation leading to pulmonary oedema and recurrent respiratory failure. Additional, properly randomized clinical trials are required to evaluate the benefits and potential hazards of surfactant replacement therapy in neonatal RDS.

Nasal fluid is a heterogeneous substance. It consists largely of a secretory product derived from the 100,000 small seromucous glands. The anterior part of the nose has a relatively high secretory capacity, but this does not seem to be caused by secretion from the 200 anterior serous glands. Compared to sputum, nasal secretion has a lower viscosity, but comparable spinability; it has a lower dry weight, and content of sulphate, sugars and most proteins, but a comparable level of albumin. Watery rhinorrhoea is mainly reflex-mediated. Watery, but not purulent nasal discharge can be reduced by the cholinoceptor antagonist, ipratropium, administered in a dose which matches the degree of the symptoms. It seems likely that the nose, in some respects, can serve as a model for the analysis of airway secretions, but a comparative study of nasal and of bronchial secretions sampled in an identical way is warranted.

Increased pulmonary proteolytic (elastolytic) activity is thought to be the primary cause of emphysema and may also play a rôle in the pathology of bronchitis. These diseases are common amongst tobacco smokers. Serum-derived alpha 1-proteinase inhibitor (alpha 1PI) and locally produced protease inhibitors normally protect the pulmonary epithelium from proteolytic attack, but tobacco smoke can inactivate these antiproteases by oxidative and non-oxidative mechanisms. Bronchoalveolar lavage fluid (BALF) samples lung surface components and most studies show that there is elevated elastolytic activity in smokers' BALF. Whether antiproteolytic capacity is reduced in these samples remains debatable. A selective lavage technique is described which independently samples central and peripheral epithelium from the same subject. Analysis demonstrates a protease-antiprotease imbalance which can differ in central and peripheral lavage and which could be significant in the development of obstructive airways disease. Therapeutic approaches include augmenting antiprotease potential using genetically engineered, oxidant-resistant alpha 1PI or synthetic peptide inhibitors.

The pharmacologic treatment of cough can be divided into two main categories: therapy with controls, prevents or eliminates cough (i.e., antitussive) and therapy that makes cough more effective (i.e., pro-tussive). Definitive antitussive therapy depends on determining the aetiology or operant pathophysiologic mechanism and then initiating specific treatment; it can be almost uniformly successful. Non-specific antitussive therapy is directed at the symptom; it is indicated when definitive therapy cannot be given. For pathologic cough in man, predominantly studied in patients with chronic bronchitis, the following non-specific antitussive drugs have been shown to be effective: aerosolized ipratropium bromide, all narcotics of the phenanthrene alkaloid group (e.g., morphine and codeine), and the non-narcotics, dextromethorphan, glaucine, diphenhydramine, caramiphen, viminol and diviminol. Although studies have shown that hypertonic saline aerosol can improve cough clearance, there are no data, to date, that have convincingly demonstrated this agent or any other pro-tussive drug to be clinically useful.