Effects of training flights of combat jet pilots on parameters of airway function, diffusing capacity and systemic oxidative stress, and their association with flight parameters

BACKGROUND

Fighter aircraft pilots are regularly exposed to physiological challenges from high acceleration (Gz) forces, as well as increased breathing pressure and oxygen supply in the support systems. We studied whether effects on the lung and systemic oxidative stress were detectable after real training flights comprising of a wide variety of exposure conditions, and their combinations.

METHODS

Thirty-five pilots of the German Air Force performed 145 flights with the Eurofighter Typhoon. Prior to and after flight lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO), alveolar volume (VA), and diffusing capacities per volume (KCO, KNO) were assessed. In addition, the fractional concentration of exhaled nitric oxide (FeNO) was determined, and urine samples for the analysis of molecular species related to 8-hydroxy-2'-deoxyguanosine (8-OHdG) were taken. For statistical analysis, mixed ANOVA models were used.

RESULTS

DLNO, DLCO, KNO, KCO and VA were reduced (p < 0.001) after flights, mean ± SD changes being 2.9 ± 5.0, 3.2 ± 5.2, 1.5 ± 3.7, 1.9 ± 3.7 and 1.4 ± 3.1%, respectively, while FeNO decreased by 11.1% and the ratio of 8-OHdG to creatinine increased by 15.7 ± 37.8%. The reductions of DLNO (DLCO) were smaller (p < 0.001) than those of KNO (KCO). In repeated flights on different days, baseline values were restored. Amongst various flight parameters comprising Gz-forces and/or being indicative of positive pressure breathing and oxygenation support, the combination of long flight duration and high altitude appeared to be linked to greater changes in DLNO and DLCO.

CONCLUSIONS

The pattern of reductions in diffusing capacities suggests effects arising from atelectasis and increased diffusion barrier, without changes in capillary blood volume. The decrease in exhaled endogenous NO suggests bronchial mucosal irritation and/or local oxidative stress, and the increase in urinary oxidized guanosine species suggests systemic oxidative stress. Although changes were small and not clinically relevant, their presence demonstrated physiological effects of real training flights in a modern 4th generation fighter jet.

Learning on the job, the use of selection, optimization, and compensation strategies, and their association with telomere length as an indicator of biological aging

PURPOSE

Due to the increased need for retention of older workforce caused by demographic changes in industrialized countries, support of healthy aging in occupational settings is of increasing relevance. This study examines the relationship between leucocyte telomere length (LTL), a potential biomarker for biological aging, and selection, optimization, and compensation (SOC) and learning opportunities as strategies involving efficient management and gain of resources at work.

METHODS

Within a cross-sectional study, blood samples were drawn from 141 geriatric care professionals to measure LTL by quantitative real-time polymerase-chain reaction. Furthermore, all participants were asked with standardized questionnaires to rate their learning opportunities at work and use of SOC strategies. Analyses were performed by multiple linear regressions.

RESULTS

SOC use, especially compensation, tended to be negatively, and learning opportunities tended to be positively associated with LTL. Furthermore, a significant interaction was found between optimization and learning opportunities, such that LTL and learning opportunities were only positively associated when optimization was high.

CONCLUSIONS

Resources at work were weakly associated with telomere length, which is not unexpected in view of the multiplicity of factors affecting LTL. The results further suggest that a mismatch between SOC and learning opportunities may negatively affect successful aging. They also suggest that more detailed research on biological aging and its relation to resources at work is needed.

Acute effects of hypertonic saline inhalation on nitric oxide pulmonary diffusing capacity in healthy adults

We investigated acute effects of inhalation of hypertonic saline solution (HSS) and oxygen (O₂, control exposure) on pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO). In a randomized crossover study, 20 healthy, non-smoking subjects were allocated to short-term inhalation of HSS or O₂. Spirometry [(forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC)] and combined single-breath DLNO-DLCO measurements were performed before and immediately after inhalation of either HSS or O₂. Percent changes were presented as median values (interquartile range). After HSS inhalation, DLNO, FEV₁ and FVC were decreased by -3.0% (-7.3, 0.5), -3.1% (-4.2, -1.6) and -1.2% (-3.3, 0.6), respectively (all P < 0.05), without significant effect on DLCO. No changes in spirometry and diffusing capacity were observed following O₂ inhalation. Acute inhalation of HSS causes a slight decrease in membrane conductance, probably as a result of fluid imbalance at the alveolar surface and interstitial fluid accumulation, both of which could impair gas exchange.

Health effects of laser printer emissions: a controlled exposure study

Ultrafine particles emitted from laser printers are suspected to elicit adverse health effects. We performed 75-minute exposures to emissions of laser printing devices (LPDs) in a standardized, randomized, cross-over manner in 23 healthy subjects, 14 mild, stable asthmatics, and 15 persons reporting symptoms associated with LPD emissions. Low-level exposures (LLE) ranged at the particle background (3000 cm^-3 ) and high-level exposures (HLE) at 100 000 cm^-3 . Examinations before and after exposures included spirometry, body plethysmography, transfer factors for CO and NO (TLCO, TLNO), bronchial and alveolar NO, cytokines in serum and nasal secretions (IL-1β, IL-5, IL-6, IL-8, GM-CSF, IFNγ, TNFα), serum ECP, and IgE. Across all participants, no statistically significant changes occurred for lung mechanics and NO. There was a decrease in volume-related TLNO that was more pronounced in HLE, but the difference to LLE was not significant. ECP and IgE increased in the same way after exposures. Nasal IL-6 showed a higher increase after LLE. There was no coherent pattern regarding the responses in the participant subgroups or single sets of variables. In conclusion, the experimental acute responses to short but very high-level LPD exposures were small and did not indicate clinically relevant effects compared to low particle number concentrations.

Hydrogen peroxide in exhaled air: a source of error, a paradox and its resolution

The concentration of hydrogen peroxide (H₂O₂) in exhaled air has been reported to be elevated in asthma and chronic obstructive pulmonary disease (COPD), but results are inconsistent and difficult to reproduce. As H₂O₂ occurs in ambient air, we examined its association with exhaled H₂O₂ in human subjects. Exhaled breath condensate (EBC) of 12 COPD patients and nine healthy control subjects was collected either with an inhalation filter (efficiency 81%) or without. Ambient air condensate (AAC) was collected in parallel and samples were analysed for H₂O₂. Additionally, ambient H₂O₂ was recorded by an atmospheric measuring device (online fluorometric measurement). H₂O₂ concentration in AAC was significantly higher (p<0.001) than in EBC. AAC variations were concordant with the data from the atmospheric measuring instrument. In both subjects' groups, the inhalation filter reduced H₂O₂ values (p<0.01). Despite generally low levels in exhaled air, analysis by a mathematical model revealed a contribution from endogenous H₂O₂ production. The low H₂O₂ levels in exhaled air are explained by the reconditioning of H₂O₂-containing inhaled air in the airways. Inhaled H₂O₂ may be one factor in the heterogeneity and limited reproducibility of study results. A valid determination of endogenous H₂O₂ production requires inhalation filters.

Biological effects of inhaled nitrogen dioxide in healthy human subjects

PURPOSE

Several epidemiological studies indicate that inhaled nitrogen dioxide (NO2) at low concentrations have been statistically associated with adverse health effects. However, these results are not reflected by exposure studies in humans. The aim of the study was to assess the acute functional and cellular responses to different NO2 concentrations in healthy human subjects with various techniques.

METHODS

Twenty-five subjects were exposed for 3 h to NO2 concentrations 0, 0.1, 0.5, and 1.5 ppm in a randomized crossover study design during 4 consecutive weeks. In each subject, lung function, diffusion capacity and exhaled nitric oxide were measured and inflammation markers were assessed in blood, nasal secretions, induced sputum and exhaled breath condensate.

RESULTS

From all lung function indices under consideration, only intrathoracic gas volume was borderline significantly increased after 0.5 ppm (p = 0.048) compared to 0.1 ppm NO2. Regarding the cellular effect parameters, the macrophage concentration in induced sputum decreased with increasing NO2 concentration, although these changes were only borderline significant (p = 0.05).

CONCLUSION

These results do not suggest a considerable acute adverse response in human subjects after 3 h of exposure to NO2 in the NO2 concentration range investigated in this study.

Heart rate variability, hemostatic and acute inflammatory blood parameters in healthy adults after short-term exposure to welding fume

The present study aimed to investigate, whether short-term experimental exposure to high levels of welding fumes would be capable of exerting acute effects in healthy subjects. Specifically, we assessed cardiovascular function in terms of heart rate variability (HRV) as well as the concentrations of inflammatory mediators and hemostatic proteins in blood as outcome measures. Twenty subjects without a history of airway and cardiovascular diseases were exposed to either control air or welding fume for 1 h on 2 separate days under standardized conditions. The median concentration of the alveolar particle fraction during welding was 3.5 mg/m(3 )(quartiles: 1.4-6.3 mg/m(3); range 1.0-25.3 mg/m(3)). Five hours later a panel of clinical assessments was performed, including HRV measurement and drawing of blood samples. There were no changes in symptom ratings or lung function after welding fume exposure. Exposures did also not differ regarding effects on time- and frequency-domain parameters of HRV. Similarly, blood leukocyte numbers, cell differentials and the blood levels of fibrinogen, C-reactive protein, antithrombin III, factor VIII, von Willebrand factor, ristocetin cofactor, sICAM-1, tumor necrosis factor alpha, interleukin 6, interleukin 8 and epithelial neutrophil activating peptide 78 were not altered by welding fume inhalation. However, there was a significant fall in the level of endothelin-1 (P < 0.01). In conclusion, the data did not indicate effects of clinical significance of a short-term high-level exposure to welding fumes on HRV or a set of blood hemostatic and acute inflammatory parameters in healthy subjects. The small but statistically significant effect on endothelin levels demonstrated that measurable effects could be elicited even in these individuals. Overall, welding fumes are not likely to exert acute cardiovascular effects in healthy individuals.

[Megakaryocytic myelosis: clinical and morphological features (author's transl)]

In general, megakaryocytic myelosis is nowadays considered to be a separate disease entity, one of the myeloproliferative syndromes. Morphologically there are localised or diffuse proliferations of usually large pleomorphic megakaryocytes and immature atypical megakaryocytes up to megakaryoblasts in the bone marrow, in the sense of a haemoblastosis. In the course of the disease megakaryocytic splenomegaly develops. A sarcomatous form (megakaryoblastoma, megakaryo-sarcoma) is rare. Megakaryocytic myelosis may arise from chronic meyloid leukaemia or polycythaemia vera, rarely as a transitional stage to an acute myeloblastic leukaemia or megakaryoblastic leukemia in the sense of a blast crisis. The mature form of the disease, which has an age peak at 59 years and is not sex-linked, often takes a course over years with increasing splenomegaly, anaemia, moderate leucocytosis and usually marked thrombocytosis (average value of 720 X 10(9)/1). Life threatening complications are haemorrhages, thromboembolism and increased frequency of infections due to antibody deficiency in the advanced stage.

[Histological examinations of late changes of bone marrow and bone following local fractionated gamma irradiation in patients with genital carcinoma (author's transl)]

In 25 patients iliac crest biopsies have been taken after radiation therapy of genital carcinoma. The radiation doses in the biopsied region ranged up to about 3,000 rads. The time interval from the end of radiation until the control biopsy was 2 months or longer, up to 25 years. The immediate consequences of the radiation, compared with the pretherapeutic picture, have been analyzed in an earlier study (Beil et al., 1974). By histomorphotometric analysis of the samples it can be shown that a more or less severe atrophy of the bone marrow is persisting in the irradiated area for years. The atrophy is accompanied either by normal or increased bony trabecularization, together with increased osteoblastic and -clastic activity. These disturbances are likely to depend of a chronic distortion of the marrow capillarization, which may be influenced by the individual RES activity; different types of the reticuloendothelial response can be demonstrated in our material. Whether this response has a bearing regarding the prognosis of the tumours condition itself remains a matter of speculation, to be proved by further investigations.

[Haematological and immunological findings in bone marrow aplasia (author's transl)]

The cellularity of the bone marrow, the number of blood cells and the immunoglobulins were investigated in 51 patients suffering from bone marrow aplasia. In this disease not only is a haematopoietic organ disturbed, but disorders of the lymphocyte and of the monocyte-systems can be detected too: the majority of patients show lymphocytopenia and monocytopenia. Immunologic reactions seem to be involved in the pathogenesis of bone marrow aplasia. The plasma cells of the bone marrow are elevated in nearly all of the patients, lymphocytes in every second case. One or several fractions of immunoglobulins are increased in about 50% and diminished in 25% of the patients.