Interplay of water and reactive elements in oxidation of alumina-forming alloys.

High-temperature alloys are crucial to many important technologies that underpin our civilization. All these materials rely on forming an external oxide layer (scale) for corrosion protection. Despite decades of research on oxide scale growth, many open questions remain, including the crucial role of the so-called reactive elements and water. Here, we reveal the hitherto unknown interplay between reactive elements and water during alumina scale growth, causing a metastable 'messy' nano-structured alumina layer to form. We propose that reactive-element-decorated, hydroxylated interfaces between alumina nanograins enable water to access an inner cathode in the bottom of the scale, at odds with the established scale growth scenario. As evidence, hydride-nanodomains and reactive element/hydrogen (deuterium) co-variation are observed in the alumina scale. The defect-rich alumina subsequently recrystallizes to form a protective scale. First-principles modelling is also performed to validate the RE effect. Our findings open up promising avenues in oxidation research and suggest ways to improve alloy properties.

Skin permeation studies of chromium species - Evaluation of a reconstructed human epidermis model.

A reconstructed human epidermis (RHE) model, the EpiDerm, was investigated and compared to human skin ex vivo regarding tissue penetration and distribution of two chromium species, relevant in both occupational and general exposure in the population. Imaging mass spectrometry was used in analysis of the sectioned tissue. The RHE model gave similar results compared to human skin ex vivo for skin penetration of CrVI. However, the penetration of CrIII into the tissue of the RHE model compared to human skin ex vivo differed markedly, such that in the RHE model the CrIII species accumulated in the tissue layer corresponding to stratum corneum whereas in human skin ex vivo, the CrIII species penetrated evenly through the skin tissue. Further, skin lipids such as cholesterol were less abundant in the RHE model compared to the human skin tissue. Results presented here indicate that the RHE models do not possess the same fundamental properties as human skin tissue. As the RHE models appear to be able to give false negative results, experiments using RHE models for the study of skin penetration should be evaluated with caution.

Repaired oesophageal atresia: respiratory morbidity and pulmonary function in adults.

Although after oesophageal atresia (OA) repair in infancy, respiratory problems are common, their natural history remains unclear. We assessed morbidity, pulmonary function (PF), and bronchial hyperresponsiveness (BHR) in adults with repaired OA respiratory. 588 patients who underwent surgery for OA during 1947-1985 were identified and those 262 who were alive and had their native oesophagus were included. Respiratory symptoms and respiratory symptom-related quality of life (RSRQoL) were assessed by questionnaire and interview, and the patients underwent spirometry, a histamine challenge test, and an exhaled nitric oxide test. For the questionnaires, we added 287 carefully matched general population-derived controls. Among the 101 (58 male) patients, median age 36 yrs (range 22-56 yrs), respiratory morbidity was significantly increased compared to controls. Patients had more respiratory symptoms and infections, as well as asthma and allergies, and more often impaired RSRQoL (p<0.001 for all). PF tests revealed restrictive ventilatory defect in 21 (21%) patients, obstructive ventilatory defect in 21 (21%) patients, and both in 36 (36%) patients. A total of 41 (41%) had BHR, and in 15 (15%), it was consistent with asthma. The most significant risk factors for restrictive ventilatory defect were thoracotomy-induced rib fusions (OR 3.4, 95% CI 1.3-8.7; p = 0.01) and oesophageal epithelial metaplasia (OR 3.0, 95% CI 1.0-8.9; p = 0.05). After repair of OA, respiratory-related morbidity, restrictive ventilatory defect and BHR extended into adulthood. Nearly half the patients had BHR and over half had a restrictive ventilatory defect. Thoracotomy-induced rib fusions and gastro-oesophageal reflux-associated oesophageal epithelial metaplasia were the strongest risk factors for restrictive ventilatory defect.

Mechanisms of asthma in Olympic athletes--practical implications.

Athletes' symptoms may only occur in extreme conditions, which are far from normal. Exercise may increase ventilation up to 200 l/min for short periods in speed and power athletes, and for longer periods in endurance athletes such as swimmers and cross-country skiers. Increasing proportions of young athletes are atopic, i.e. they show signs of IgE-mediated allergy which is, along with the sport event (endurance sport), a major risk factor for asthma and respiratory symptoms. Mechanisms in the etiology and clinical phenotypes vary between disciplines and individuals, and it may be an oversimplification to discuss athlete's asthma as a distinct and unambiguous disease. Nevertheless, the experience on Finnish Olympic athletes suggests at least two different clinical phenotypes, which may reflect different underlying mechanisms. The pattern of 'classical asthma' is characterized by early onset childhood asthma, methacholine responsiveness, atopy and signs of eosinophilic airway inflammation, reflected by increased exhaled nitric oxide levels. Another distinct phenotype includes late onset symptoms (during sports career), bronchial responsiveness to eucapnic hyperventilation test, but not necessarily to inhaled methacholine, and a variable association with atopic markers and nitric oxide. A mixed type of eosinophilic and neutrophilic airway inflammation seems to affect especially swimmers, ice-hockey players, and cross-country skiers. The inflammation may represent a multifactorial trauma, in which both allergic and irritant mechanisms play a role. There is a significant problem of both under- and overdiagnosing asthma in athletes and the need for objective testing is emphasized. Follow-up studies are needed to assess the temporal relationship between asthma and competitive sporting, taking better into account individual disposition, environmental factors (exposure), intensity of training and potential confounders.

Intense physical training decreases circulating antioxidants and endothelium-dependent vasodilatation in vivo.

Physical training increases free radical production and consumes antioxidants. It has previously been shown that acute exercise markedly increases the susceptibility of LDL to oxidation but whether such changes are observed during physical training is unknown. We measured circulating antioxidants, lipids and lipoproteins, and blood flow responses to intrabrachial infusions of endothelium-dependent (acetylcholine, ACh, L-N-monomethyl-arginine, L-NMMA) and -independent (sodium nitroprusside, SNP) vasoactive agents, before and after 3 months of running in 9 fit male subjects. Maximal aerobic power increased from 53 +/- 1 to 58 +/- 2 ml/kg min (P < 0.02). All circulating antioxidants (uric acid, SH-groups, alpha-tocopherol, beta-carotene, retinol) except ascorbate decreased significantly during training. Endothelium-dependent vasodilatation in forearm vessels decreased by 32-35% (P < 0.05), as determined from blood flow responses to both a low (10.8 +/- 2.1 vs. 7.3 +/- 1.5 ml/dl min, 0 vs. 3 months) and a high (14.8 +/- 2.6 vs. 9.6 +/- 1.8) ACh dose. The % endothelium-dependent blood flow (% decrease in basal flow by L-NMMA), decreased through training from 37 +/- 3 to 22 +/- 7% (P < 0.05). Blood flow responses to SNP remained unchanged. The decrease in uric acid was significantly correlated with the change in the % decrease in blood flow by L-NMMA (r = 0.74, P < 0.05). The lag time for the susceptibility of plasma LDL to oxidation in vitro, LDL size and the concentration of LDL cholestetol remained unchanged. We conclude that relatively intense aerobic training decreases circulating antioxidant concentrations and impairs endothelial function in forearm vessels.

Effects of morphine, physostigmine and raphe nuclei stimulation on 5-hydroxytryptamine release from the cerebral cortex of the cat.

1. The release of 5-hydroxytryptamine (5-HT) from the cerebral cortex and caudate nucleus of brainstem-transected cats and from the cerebral cortex of rats anaesthetized with urethane was determined by radioenzymatic and biological assay. 2. The stimulation of nucleus linearis intermedius of raphe doubles the basal 5-HT release in the caudate nucleus and increases it 3 fold in the cerebral cortex. The effects of the electrical stimulation of the raphe are potentiated by chlorimipramine. 3. Brain 5-HT release is greatly increased by morphine hydrochloride (6 mg/kg i.v.) and by physostigmine (100 microgram/kg i.v.), but not by DL-DOPA (50 mg/kg i.v.). 4. It is suggested that the 5-HT releasing action of physostigmine can contribute to some of its pharmacological effects such as the analgesic effect so far attributed exclusively to its indirect cholinomimetic activity. 5. The 5-HT releasing action of physostigmine seems unrelated to its anticholinesterase activity.

Reversible inhibition of acetylcholinesterase by eseroline, an opioid agonist structurally related to physostigmine (eserine) and morphine.

The action of eseroline--(3aS,8aR)-1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethylpyrrolo[2,3-b]indo l-5-ol--salicylate was tested on preparations of ChE from different sources and on the longitudinal muscle of guinea-pig ileum. While eseroline is eseroline is extremely weak-acting on horse serum BuChE (Ki = 208 +/- 42 microM), it is a rather strong competitive inhibitor of AChE's, its Ki being 0.15 +/- 0.08 microM, 0.22 +/- 0.10 microM and 0.61 +/- 0.12 microM in electric eel, human RBC and rat brain, respectively. Eseroline inhibitory action in AChE in independent of the duration of pre-incubation and appears fully developed in less than 15 sec. This action is also rapidly reversible; after pre-incubation followed by dilution, maximum enzymic activity is regained within 15 sec. The electrically-evoked contractions of the longitudinal strip were inhibited by concentrations of eseroline in the range 0.2-15 microM, while they were increased by concentrations over 20 microM. In the same preparation, without electrical stimulation, but in the presence of naloxone, eseroline induced contractions at concentrations higher than 5 microM. This effect was antagonized by atropine. The inhibitory activity of eseroline parallels, as regards selectivity, potency and kinetics, that of the phenolic anticurare agent edrophonium, while it differs markedly from that of physostigmine.

Alterations in bronchoalveolar lavage fluid but not in lung function and bronchial responsiveness in swine confinement workers.

Testing of lung function and bronchial reactivity, bronchoalveolar lavage (BAL), and a skin prick test with a standard panel and six "swine" extracts obtained from swine and swine environment were performed in 20 randomly selected nonsmoking swine confinement workers. In addition, blood samples for detection of antibodies by the diffusion in gel-enzyme-linked immunosorbent assay (DIG-ELISA) technique and precipitating antibodies were drawn. Air samples for measurement of dust and endotoxin levels were collected. All the farmers regarded themselves as healthy. The results were compared with reference groups consisting of urban nonsmoking subjects who had not been exposed to pig farming environment. The pig farmers had normal lung function and the bronchial reactivity was not different from the reference group. In the BAL fluid of the farmers, the concentration of total cells and granulocytes was increased while the concentrations of lymphocytes and macrophages were normal. The BAL fluid concentrations of albumin, fibronectin, and hyaluronan were elevated in the farmers. Skin prick tests with swine extracts were negative in all farmers. Antibodies (assessed by DIG-ELISA) against swine dander, swine dust, and pig feed were increased and precipitating antibodies against swine dander were found in 14, against pig food in five, and against swine confinement dust in three of the 20 pig farmers. The concentration of airborne total dust was 7.4 mg/cu mm and the endotoxin concentration was 37 (22 to 60) ng/cu mm during tending the pigs and increased, during feeding, to 13.8 mg/cu mm and 315 (194 to 716) ng/cu mm, respectively. There was no correlation between exposure and lung function or lavage findings. In conclusion, randomly selected pig farmers had signs of airway inflammatory reaction and activation of the immune system without alteration in lung function and bronchial reactivity.

Different response to doubling and fourfold dose increases in methacholine provocation tests in healthy subjects.

RATIONALE: In a modified methacholine provocation test that was used to study changes in airway responsiveness to occupational irritants or sensitizers in healthy subjects, two protocols were used: a long protocol (doubling methacholine concentrations between dose steps) or a short protocol (fourfold increases in concentration). This modified methacholine provocation allows measurements of the provocative dose causing 20% decrease in FEV(1) (PD(20)) in a high proportion of a normal population. METHODS: The distribution of PD(20) was investigated in healthy nonatopic men without history of allergy or asthma symptoms using the long protocol (n = 101) or the short protocol (n = 309). In addition, 30 healthy subjects underwent methacholine provocation tests using both protocols. RESULTS: PD(20) was defined in 79% of subjects with the long protocol and in 48% of subjects with the short protocol. The provocative concentration of methacholine causing a 20% decline in FEV(1) (PC(20)) and PD(20) were significantly lower using the long protocol: long-protocol PC(20) (median [25th to 75th percentile]), 19.9 mg/mL (3.9 to > 32 mg/mL) compared with short-protocol PC(20), > 32 mg/mL (8.7 to >32 mg/mL; p < 0.0001); long-protocol PD(20), 4.2 mg (1.6 to 20 mg) compared with short-protocol PD(20), > 13.7 (2.6 to > 13.7 mg; p = 0. 006). The differences in PD(20) using short and long protocols were confirmed in a randomized trial of 30 healthy subjects tested with both protocols. CONCLUSION: Using doubling concentrations, PC(20) and PD(20) could be defined in a higher proportion of healthy subjects than a protocol using fourfold dose increases. Furthermore, the doubling protocol results in a PD(20) estimate that is less than half the value obtained when using a protocol with fourfold concentrations between dose steps. The difference remains, whether the methacholine effect is regarded as cumulative or noncumulative. The explanation for the difference between the protocols is unclear.

Exposure to microorganisms associated with allergic alveolitis and febrile reactions to mold dust in farmers.

STUDY OBJECTIVE: To compare exposure to microorganisms associated with allergic alveolitis (AA) and with febrile reactions to inhaled mold dust (organic dust toxic syndrome [ODTS]) in farmers and in normal subjects. DESIGN: A prospective study in which exposure was evaluated within two weeks of medical consultation for AA or ODTS. Samples were collected during normal farming (background) and during the handling of materials associated with disease or causing maximal exposure in reference farms (worst case). SETTING: Swedish farms PARTICIPANTS: Eleven farmers with a confirmed diagnosis of AA from ten farms, 16 subjects with symptoms of ODTS from 12 farms, and 17 reference farmers. MEASUREMENTS AND RESULTS: Worst-case samples representative of the exposure preceding disease were obtained on four farms where five farmers had had AA; the samples contained on average 2.6 +/- 1.8 x 10(9) (SD) spores/m3 of air. On six farms where nine farmers had had ODTS, representative samples averaged 13 +/- 13 x 10(9) spores/m3, and on reference farms this figure was 0.12 +/- 0.20 x 10(9) spores/m3. The daily spore dose associated with allergic alveolitis was 2 x 10(9) spores/d, which was ten times higher than on reference farms. The average dose associated with ODTS was 2 x 10(10) spores. Worst-case samples, collected during 10 to 30 min, contributed to more than 90 percent of the day exposure on farms where AA or ODTS had occurred. CONCLUSION: Allergic alveolitis was associated with high exposure levels on most weekdays for weeks, and ODTS was associated with extreme exposure occurring on a single day. There was no correlation with individual spore types and disease and the present results are compatible with a hypothesis that common cell wall components of microorganisms may cause "toxic" symptoms and stimulate immune reactions.

Hyaluronic acid (hyaluronan) in BAL fluid distinguishes farmers with allergic alveolitis from farmers with asymptomatic alveolitis.

Pulmonary function measurements, bronchoalveolar lavage (BAL), and analyses of precipitating antibodies in blood were performed in 12 farmers wtih no symptoms from the airways and 12 farmers who were admitted to the hospital due to acute symptoms of alveolitis (all nonsmokers). In addition, a bronchial methacholine provocation test was performed in the asymptomatic farmers. In 11 of the 12 symptomatic farmers but in none of the asymptomatic farmers, precipitating antibodies against one or more of the microorganisms which usually occur in a farmer's environment were found. In the farmers with symptomatic alveolitis, a restrictive impairment of pulmonary function was found, while pulmonary function was normal in all asymptomatic farmers. Findings in the BAL fluid showed increased concentrations of total cells, lymphocytes, and neutrophils and elevated levels of albumin, fibronectin, and angiotensin-converting enzyme in asymptomatic farmers compared with our own reference group. The same analyses in BAL fluid from the symptomatic farmers revealed a further increase in all parameters compared with the asymptomatic farmers. The BAL fluid from asymptomatic farmers had normal levels of hyaluronic acid (hyaluronan) and procollagen 3 N-terminal peptide, while these levels were significantly increased in the symptomatic group. We conclude that inflammation in the alveolar space and signs of activation of alveolar macrophages are present in farmers regardless of respiratory symptoms, although these findings are more pronounced in the presence of symptoms of acute alveolitis; however, the findings of impaired pulmonary function and the occurrence of precipitins and elevated levels of hyaluronic acid and procollagen 3 N-terminal peptide in BAL fluid were exclusively found in the farmers with airways symptoms. We postulate the hyaluronic acid, due to its pronounced ability to immobilize water, may be of importance in the development of the pulmonary function impairment observed in farmer's lung disease.

Direct evidence that eseroline possesses morphine-like effects.

The opiate-like effects of eseroline, a physostigmine derivative, were studied in different tests. The antinociceptive effect of eseroline given s.c. and intracerebrally could be detected in the rat hot plate test and was reversed by naloxone. The apparent pA2 values of naloxone demonstrated with eseroline and morphine were found to be equal, suggesting an effect on similar receptors. Eseroline also had opiate agonist activity on the isolated longitudinal muscle strip of guinea pig ileum and isolated nictitating membrane of the cat: presynaptically, it inhibited the contractions evoked by stimulation and its effect was antagonized by naloxone. Eseroline reduced acetylcholine release from the myenteric plexus of the longitudinal muscle strip when the cholinesterases had been inhibited by physostigmine. In addition, it was also found that eseroline antagonized the inhibitory effect of normorphine in the longitudinal muscle strip and potentiated the effect of exogenous acetylcholine on smooth muscle, both effects being attributed to its anticholinesterase activity. The analgesic effect of eseroline was not related to its anticholinesterase activity.

Inhalation of swine-house dust increases the concentrations of interleukin-1 beta (IL-1 beta) and interleukin-1 receptor antagonist (IL-1ra) in peripheral blood.

Inhalation of dust in swine confinement buildings causes airway inflammation and systemic symptoms. The proinflammatory cytokines interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) increase in bronchoalveolar and nasal lavage fluid, and in serum. The aim of this investigation was to study changes in the IL-1 family of cytokines in peripheral blood in 36 healthy volunteers exposed to swine house dust for 3 h. Interleukin (IL-1 beta) was measured in platelet poor plasma and in a mononuclear cell fraction (PBMC) and interleukin-1 receptor antagonist (IL-Ira), IL-6 and TNF-alpha were measured in serum 4 and 7 h after the start of 3 h exposure. Lung function and a methacholine bronchial provocation test were performed before and 7 h after the start of exposure. The leukocyte count in whole blood and the mononuclear cell count in PBMC were examined before, and 4 and 7 h after the start of exposure. The concentration of airborne inhalable dust and endotoxin were measured using personal samples. The concentration of inhalable dust was 23 (20-30) mg m-3 (median 25th-75th percentile) endotoxin was 1.1 (0.8-1.4) micrograms m-3 and respirable dust (n = 8) was 1.0 (0.7-1.2) mg m-3. IL-1 beta increased from < 0.125 to 0.9 (0.5-1.3) ng l-1 in plasma and from 1.6 to 2.7 (1.1-4.4) ng l-1 in PBMC (P < 0.01). IL-1 ra, IL-6 and TNF-alpha increased 2-, 12- and 2-fold in serum after exposure, respectively. Changes in IL-1 ra correlated with changes in FEV1, bronchial responsiveness, oral temperature (P < 0.01) and blood white cell count (P < 0.05). IL-1 beta correlated significantly with temperature (P < 0.05). These results indicate that IL-1 beta and IL-1 ra increase in peripheral blood following inhalation of swine house dust and may participate in and modulate the inflammatory response together with IL-6 and TNF-alpha.

Is asthma underestimated as a cause of sick leave?

Public interest needs to be focused on the economic burden of asthma on society because of the increasing prevalence of the condition. Asthma is common in individuals of working age and sick leave is an important health-economic issue. In the present study we looked at the prevalence of asthma in a sick leave register. Individuals on sick leave due to asthma, individuals on sick leave due to any other respiratory disorder or symptom and individuals on sick leave due to non-respiratory conditions were included in a questionnaire based study. Individuals in the register diagnosed with asthma could be classified as current asthmatics or possible asthmatics in respectively 94% and 99% of the cases. They were also ex-smokers to a greater extent than the other groups, which was more pronounced in males. However, individuals on sick leave due to 'any other respiratory disorder' could be classified as current asthmatics or possible asthmatics in respectively 19% and 30% of the cases. The corresponding figures in the group on sick leave due to 'other diagnoses' were 7% and 10%. Hence, there is evidence that asthma is an under-reported diagnosis and this must be taken into consideration when sick leave registers are used in health-economic studies.

The salt output of a nebulizer--a comparison between two nebulizer types.

The output of a nebulizer is generally defined as its weight loss during 1 min of nebulization. This mass output includes the weight loss due to evaporation of the solution required to moisten the dry air that is fed through the nebulizer. In order to compare results obtained from studies using different nebulizers we introduce the salt output as the amount of the solution that actually leaves the liquid phase as droplets and not by evaporation. The performance characteristics of a standard jet nebulizer (MA2) and a Sidestream jet neublizer were compared. Mass output was determined at different methacholine concentrations. Salt output was assessed by analysing the remaining salt in the nebulizers after 1 min of nebulization. Overall system performance in terms of forced expiratory volume in 1 sec (FEV1) reduction after 1 min of exposure to individually selected concentrations of methacholine were studied in 15 healthy, non-smoking subjects. Both nebulizer types showed a moderate linear increase of mass output with methacholine concentration. The efficiency coefficient, the quotient between salt output and mass output, was found to be 0.93 and 0.75 for the MA2 and Sidestream nebulizer respectively. These findings were explained by differences in airflow through, and temperature inside, the nebulizers. The salt output of the nebulizers proved to be better correlated to the FEV1-reduction following methacholine inhalation than did the mass output. The relative amount of the salt output that adhered to the acrylic walls of the Sidestream nebulizer drying tower was found to be 9%. We conclude that it is more appropriate to use salt output than mass output as a nebulizer performance descriptor. The study also shows the importance of determining nebulizer system performance under conditions as similar to true provocations as possible.

Altered regulation of breathing after bilateral lung transplantation.

In our previous animal studies on dogs, regulation of breathing was found to be altered after en bloc transplantation of the heart and both lungs. During carbon dioxide (CO2) inhalation the minute volume was increased due to an increase of tidal volume after transplantation whereas before transplantation both respiratory frequency and tidal volume increased. The success of the heart-lung transplantation was based on experiments on baboons as no long-term survivors were obtained in dogs. It was thought that the regulation of breathing is different in dogs and primates. We therefore decided to study the regulation of breathing in humans after bilateral lung transplantation during CO2 stimulation. The regulation of breathing was tested 2 to 4 months after bilateral lung transplantation in six patients. Six healthy subjects with intact lungs were tested as controls. The test persons were allowed to breathe first room air, then 5% CO2 in air for 4 min and then room air again. The frequency of respiration, tidal volume and minute ventilation were recorded using a phneumotachograph. Simultaneously samples of arterial blood were drawn from a cannulated brachial artery for analysis of pressure of arterial oxygen (PaO2), pressure of arterial carbon dioxide (PaCO2), base excess (BE) and pH. During inhalation of CO2 for 4 min the minute volume doubled in both transplant patients and in controls. The tidal volume of the transplant patients increased significantly more than that of the controls (P < 0.005) whereas respiratory frequency increased significantly only in the controls with intact lungs (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Gram positive bacteria induce IL-6 and IL-8 production in human alveolar macrophages and epithelial cells.

BACKGROUND AND OBJECTIVE: Inhalation of dust from swine confinement buildings results in an acute inflammatory reaction in the respiratory tract. The dust has a high microbial content, dominated by Gram positive bacteria. The aim of the present study was to evaluate the significance of bacteria in the induction of IL-6 and IL-8 release from respiratory epithelial cells and alveolar macrophages. The results would give an indication to what extent the bacteria contribute to the toxic inflammation following exposure to swine dust. METHODS: Epithelial cells from a human lung carcinoma cell line (A549) and human alveolar macrophages obtained from healthy subjects by bronchoalveolar lavage, were stimulated with swine dust, LPS, one Gram negative and four Gram positive bacteria strains. The dose-response release of IL-6 and IL-8 were studied. In addition, a bacteria-free supernatant was prepared from each strain and used for stimulation. RESULTS: With a few exceptions, a dose-dependent IL-6 and IL-8 release was demonstrated from both cell types after stimulation with bacteria. In epithelial cells, Escherichia coli was the most potent bacteria at the highest concentration of 400 bacteria/cell regarding secretion of both IL-6 and IL-8 (P < 0.001), followed by Staphylococcus hominis and Staphylococcus lentus. In alveolar macrophages, S. lentus was the most potent strain (P < 0.001) in inducing cytokine release (P < 0.001), followed by S. hominis and E. coli concerning IL-6 secretion or Micrococcus luteus and E. coli with respect to IL-8 secretion (P < 0.001). Differences in potency between the various bacteria could be demonstrated, both within the two cell types as well as between the epithelial cells and macrophages. Bacteria-free supernatants were also able to induce cytokine release in both cell types. In macrophages the supernatants were even more potent stimuli than whole bacteria. CONCLUSIONS: The results indicate that bacteria or bacterial products could be an important contributing factor to the inflammatory reaction following exposure to swine dust.

Characterization of exposure to molds and actinomycetes in agricultural dusts by scanning electron microscopy, fluorescence microscopy and the culture method.

Air samples from 79 farms with 10(5) to 10(11) microorganisms/m3 were analyzed by scanning electron microscopy (SEM), fluorescence microscopy (FM), and the culture method. The total exposure to microorganisms (particularly actinomycetes) was underestimated when assessed as colony-forming units (cfu). The average cfu count was one-sixth of the total count according to SEM or FM, and the individual variability was great. This occurrence was partly explained by the aggregation of spores. Single spores accounted for 2-65% of all spores in 35 samples. There was an average of three spores/particle, and 93 (range 67-100)% of the spores were single or in aggregates of respirable size. Aggregation was more pronounced for actinomycetes and at high spore counts. Actinomycetes and bacteria could not be distinguished by FM. Bacteria (other than actinomycetes) were not detected by SEM, yet the total count of microorganisms was similar for FM and SEM. Most particles were spores from actinomycetes and fungi of the genera Aspergillus or Penicillium.

Impact of occupation on respiratory disease.

OBJECTIVES: This study identified occupations with a marked impact on sick leaves due to respiratory disease. METHODS: A national sick-leave register containing information on all sick leaves exceeding 14 days, physicians' diagnoses, and the occupational status of all manual and service employees in the private sector in Sweden was studied. Sick leaves during 1992-1994 (N=210,755) were analyzed with special attention to respiratory disease and occupation. RESULTS: Respiratory disease accounted for 4.4% of the total number of sick leaves. The incidence of long-term (> or = 90 days) sick leaves due to respiratory disease was 3 times higher in occupations with a high incidence than in those with a low incidence. There was a high correlation (r=0.80) between the incidence of long-term sick leave due to respiratory disease and sick leave due to all other conditions; this finding suggests that market and selection factors may play an important role in determining the overall risk for sick leave in various occupations. The proportion of sick leaves due to long-term respiratory disease out of all long-term disease was compared between occupations. Agricultural workers had a 46% higher proportion of long-term respiratory disease than metal workers. Industrial workers, food industry workers, and painters were also occupations with an increased risk. These findings could not be explained by differences in age or smoking habits. CONCLUSIONS: Major differences were found among manual and service occupations regarding long-term sick leave due to respiratory disease. Several occupations, in which exposure to respiratory sensitizers and irritants are known to occur, were among those in which workers had an increased risk for long-term respiratory disease.

Exposure to microorganisms, febrile and airway-obstructive symptoms, immune status and lung function of Swedish farmers.

A questionnaire was sent to 512 farmers, members of a local farmer's health association. Eighty were interviewed, and their serum precipitins and total serum immunoglobulin E (IgE) values were determined. Forty-five underwent extensive pulmonary function tests. On the basis of the clinical evaluation it was estimated that 19% of the farmers had experienced febrile reactions (fever and/or shivering) following exposure to organic dust, 50% of the 19% having been exposed within the last 2.5 years. Common causes were moldy grain, hay, and woodchips. The pulmonary function, gas exchange, and chest radiographs of those who had previously had febrile reactions were normal. Only 13% showed positive precipitin reactions in Ouchterlony double-diffusion tests. With more sensitive tests, positive precipitins were found in 59%, but they were negatively correlated with febrile episodes. Air samples collected during work with hay and grain on 21 farms contained between 10(7) to 2 X 10(9) microorganisms/m3. The highest values were associated with symptoms of alveolitis. Eleven percent of the farmers reported obstructive chest symptoms following exposure to organic dust. This group showed decreased pulmonary function and elevated serum IgE levels and included a high proportion of smokers and exsmokers. No correlation was found between febrile and obstructive reactions.