Influence of the professional activity of pilots on the adaptive pattern of hemodynamic reactions to the tilt test

A comparative study of the blood circulation??s response to the tilt test was performed in three groups of healthy subjects: AF pilots (n = 72), engine drivers (n = 44), and students at the Military Institute of Radio Electronics (n = 32). In all the groups, adequate adaptive responses to the test were recorded under eukinetic hemodynamics where steady cardiac output and blood pressure values combined with an increase of the heart rate by 10?C12%. Hypokinetic hemodynamics caused a 20% increase in cardiac output during the initial 5 min of orthostasis in pilots versus an 8?C12% increase in the others. Hyperkinetic hemodynamics were responsible for the increase in the cardiac output in pilots but not in the other groups. Parasympathetic system activation was peculiar of hypokinetic hemodynamics, while sympathetic system activation was associated with hyperkinetic hemodynamics. These results suggest a larger body functional reserve in pilots compared to other subjects as a side effect of their profession.     

Effect of motor load on the course of functional maturation of the autonomic control of the cardiovascular system of adolescents

A comparative study of the state of the cardiovascular systems of adolescents not engaged in sports and young athletes of the same age has been performed. According to the indices recorded in the resting state, a relative lag of the functional development of the systems of autonomic control of the cardiovascular system was shown for adolescent nonathletes at an age of 13–14 years as compared with young athletes. This lag is compensated by the age of 15–16 years, but the adequate level of autonomic activity is reached through the activation of central regulatory mechanisms (sympathetic and humoral), with a relatively low contribution of the peripheral vagal and baroreflex mechanisms. This conclusion is confirmed by the results of assessment of the reactivity of the cardiovascular system of adolescents with different levels of motor activity in a functional test with limited pulmonary ventilation.     

Administration of a synthetic antiprotease reduces smoke-induced lung injury.

Our previous studies suggest that a neutrophil-mediated inflammatory injury causes a major fraction of the pulmonary edema that occurs after smoke inhalation. Because activated neutrophils extrude cytotoxic proteases, the current study was conducted to evaluate the role of proteases in the pulmonary microvascular injury. Twelve sheep, instrumented for collection of lung lymph, were insufflated with cotton smoke. The sheep were treated 30 min after smoke inhalation with either gabexate mesilate (an inhibitor of serine proteases) or vehicle. Smoke inhalation resulted in an increased protease activity in the lung interstitium, as evidenced by decreases in both antiprotease activity and immunoreactive alpha 2-macroglobulin. Intravenous infusion of gabexate mesilate prevented the decrease in antiprotease activity. The protease inhibitor significantly attenuated the smoke-induced increase in transvascular fluid and protein flux, with untreated animals exhibiting 460% increases in flux compared with 180% in the inhibitor treated sheep. The protease inhibitor also eliminated the functional degradation in gas exchange that was observed in the untreated sheep. These studies strongly suggest that an increase in pulmonary proteolytic enzyme activity is responsible for a significant fraction of the degradation in microvascular integrity and gas exchange that is associated with smoke inhalation injury.     

Evaluation of the functions of human neutrophils by their reaction to a bacterial stimulus

The principle of functional loading, i.e. stimulation of the neutrophiles with enterobacterial inactivated vaccine in vitro or with bacterial polysaccharides in vivo followed by the NBT-test is recommended for adequate estimation of the neutrophile link in the system of the host defense from infections. 97 practically healthy persons were examined in Novosibirsk and Norilsk and it was shown that in the regions of the Far North there were differences among the population with respect to the initial functional activity of the neutrophiles and especially with respect to their reaction to the stimulation. The effect of neutrophile stimulation in vitro with an inactivated vaccine of Serratia marcescens was higher and more stable than that with a single inhalation of prodigiosan. The prevalence of the least pathway providing increased resistance of the phagocytosing cells to infection in the population of the Far North might be the cause of a significant risk of infectious diseases in them.     

Evaluation of the Blood Circulation System in Pilots of Deck Aircrafts during Long-distance Missions

The goal of this study was to evaluate the state of cardiovascular system in fighter and helicopter pilots during a long-distance naval mission. The study was carried out aboard a heavy aircraft carrier in pilots of deck aircrafts, and its participants were represented by 17 fighter pilots, 9 helicopter pilots, as well as 21 flight operations controllers. The circulation indicators were studied by the method of volumetric compression oscillography, using an APKO-8 oscillometric analyzer of circulation. An AnnaFlash 2000 digital 24-h ECG accumulator was used to monitor the time course of heart rate (HR) in fighter and helicopter pilots flying off the deck of the carrier. The analysis of the central and peripheral hemodynamic indicators has shown a significant predominance of pilots with prehypertension and mild hypertension among the flight personnel of deck-based aviation. Maximal values of systolic, diastolic, and mean blood pressure prevailed in helicopter pilots, while minimal values were characteristic of fighter pilots. Differences in these parameters between helicopter and fighter pilots tended to increase gradually with the duration of the long-distance mission. Maximum HR increases (up to 157 bpm) were recorded in fighter pilots during landing on the carrier deck). The most stressful task for helicopter pilots proved to be the descent of a rescuer in a winch, which was evidenced by the HR values increasing up to 132 bpm. The indicators of adaptation to the conditions of a naval mission varied within wide ranges. Fighter pilots adapted themselves more successfully than helicopter pilots. Hence the conclusion about the necessity to upgrade the system of flight personnel selection and training for operating under the conditions of a long-distance naval mission, as well as the monitoring of the health state of pilots.     

Development of a rodent lung macrophage chromosome aberration assay

Lung macrophages are the first line of defense against inhaled xenobiotics. They are able to accumulate airborne particulates as well as having metabolic capability. They may thus be sensitive indicator cells for detecting inhalation exposure to environmental mutagens. Their usefulness as a short-term in vivo genotoxic assay has not, however, been adequately explored. We have systematically investigated the feasibility of developing a lung macrophage chromosome-aberration assay. It was found that with different types of spindle-binding chemicals (vinblastine and vincristine), and with improved harvesting procedures, an adequate number of metaphase cells can be collected from mice and Chinese hamsters. The chromosome aberration frequencies in macrophages from control mice and Chinese hamsters were found to be 1.2 +/- 2.3 and 0.75 +/- 2.2 per 100 cells respectively. These frequencies are within normal ranges for other somatic cells. After inhalation exposure to an occupational-exposure level of benzene (0, 0.1 and 1 ppm), significant dose-dependent induction of aberrations (1.2 +/- 2.3, 5.7 +/- 6.3 and 6.8 +/- 6.2 chromatid deletions per 100 cells resp.) were observed in the macrophages. Thus, these cells can be used as one of a battery of in vivo assays for inhalation exposure studies.     

The Role of the Sympathoadrenomedullary System in the Formation of Pilot’s Adaptation to Flight Loads

The objective of this study was to evaluate the functions of the sympathoadrenomedullary system and the related psychophysiological reactions of pilots, depending on flying hours on a highly maneuverable aircraft. The study involved 78 volunteer pilots (41 high-maneuverability pilots and 37 bomber and transport aviation pilots). A set of methods was chosen with the possibility of their use according to the principle of comprehensive evaluation of the body functional state under flight loads taken into account. Our results indicate that highly maneuverable aircraft piloting induces a significant activation of the sympathoadrenomedullary system in pilots, compared to bombing and transport aircrafts. This is particularly common to young pilots with the total flying time of less than 1000 h. It has been recorded that changes in adaptation to the effect of flight factors on the body develop with age and flight experience.     

Monitoring the functional state of human operators by the parameters of the fundamental tone and spectrum of speech

The possibility of distant monitoring of the functional state of a human operator by speech signal parameters is considered. Examples of this monitoring in pilots during simulated and real flights are presented.     

Protective and adaptive reactions of the air-conducting and respiratory portions of the lungs to exposure to atmospheric pollutants

A complex structural-functional investigation of protective-adaptive reactions of various parts in the lungs has been performed under inhalation of some toxic substances. To a continuous inhalation effect of 1,2-dichlorpropane, 132 non-inbred white rats have been subjected. At the first stage of the investigation, using specific loading tests, periods for formation of increased and decreased resistivity of the experimental animals have been defined. Under the given scheme of the experiment the state of a maximal resistivity develops by the 30th day of the influence, then it gradually decreases and in 60 days becomes significantly lower than in the control animals. Synchronous changes in resistivity and in loading of the respiratory organs are revealed. The structural-functional investigation of the pneumatic and respiratory parts of the lungs during the period of formation (in 5 days of the influence), at maximum (in 30 days of the influence) and at decreased resistivity (in 60 days of the influence) makes it possible to establish that functional activity of the aero-hematic, aero-epithelial barriers and the surfactant system of the lungs increases during the period of elevated resistivity and decreases at the stage of reduced endurance to the loading. A suggestion is made that, together with other factors, increasing functional activity in the systems studied is an essential component for formation of the elevated stability of the organism against toxic inhalation.     

Real-Time State Estimation in a Flight Simulator Using fNIRS

Working memory is a key executive function for flying an aircraft. This function is particularly critical when pilots have to recall series of air traffic control instructions. However, working memory limitations may jeopardize flight safety. Since the functional near-infrared spectroscopy (fNIRS) method seems promising for assessing working memory load, our objective is to implement an on-line fNIRS-based inference system that integrates two complementary estimators. The first estimator is a real-time state estimation MACD-based algorithm dedicated to identifying the pilot’s instantaneous mental state (not-on-task vs. on-task). It does not require a calibration process to perform its estimation. The second estimator is an on-line SVM-based classifier that is able to discriminate task difficulty (low working memory load vs. high working memory load). These two estimators were tested with 19 pilots who were placed in a realistic flight simulator and were asked to recall air traffic control instructions. We found that the estimated pilot’s mental state matched significantly better than chance with the pilot’s real state (62% global accuracy, 58% specificity, and 72% sensitivity). The second estimator, dedicated to assessing single trial working memory loads, led to 80% classification accuracy, 72% specificity, and 89% sensitivity. These two estimators establish reusable blocks for further fNIRS-based passive brain computer interface development.     

Structural and functional reserves of the autonomic nervous system in pilots of high-maneuver aircrafts

The purpose of the study was to analyze morbidity among pilots of different categories of aircraft and to investigate reactivity of the autonomic nervous system (ANS) in pilots of high-maneuver aircrafts who varied in age and flying time. Morbidity of the flying personnel was analyzed based on the data of aviation medical exams. The ANS investigation involved 56 pilots of fighter and assault aircrafts both in inter-flight periods and during duty shifts. Cytochemistry was used to measure glycogen in peripheral blood neutrophils in 77 pilots. It was shown that the pre-stress state in pilots with a flying time of more than 1000 h may transform into chronic stress, provided that flight duties remain heavy. Cytochemical data studies of the concentration of neutrophilic glycogen revealed that the level of this substance was controlled by hormonal components of the sympathetic and parasympathetic divisions of the ANS and indicated the energy potential of peripheral blood leukocytes.     

Effect of radish (Raphanus sativus Linn.) on thyroid status under conditions of varying iodine intake in rats

Cruciferous plants viz. cabbage, cauliflower, turnip, radish, mustard etc. that contain goitrogenic/antithyroid substances, constitute a portion of regular human diet. The effect of chronic feeding of fresh and cooked radish, R. sativus under varying state of iodine intake on morphological and functional status of thyroid in albino rats was evaluated by thyroid gland morphology and histology, thyroid peroxidase activity, serum triiodothyronine, thyroxine and thyrotropin levels. The consumption pattern of iodine and goitrogens of cyanogenic origin was evaluated by measuring urinary iodine and thiocyanate levels respectively. After chronic radish feeding, increased weight of thyroid gland, decreased thyroid peroxidase activity, reduced thyroid hormone profiles and elevated level of thyrotropin were observed resembling a relative state of hypoactive thyroid gland in comparison to control even after supplementation of adequate iodine.     

Behavioural and functional vestibular disorders after space flight: 2. Fish,amphibians and birds

The review presents data on functional changes in fish, amphibians and birds associated with otolith organ activity after exposure to weightlessness during spaceflight. These data are of importance both for solving some fundamental problems of vestibulology and for practice. In the latter case, lower vertebrates are considered as a convenient and, most importantly, adequate model to unravel the mechanisms of vestibular disorders in humans. Analysis of the experimental results shows that weightlessness exerts no substantial effect on the formation and functional state of the otolith system in embryos of fish, amphibians and birds developing during spaceflight. Moreover, they even promote faster embryonic development of fish and amphibians as shown for mammalian fetuses. The experiments show that both in lower and higher vertebrates weightlessness brings about similar functional and behavioral changes. For example, in fish hatchlings and amphibian tadpoles (without lordosis) the vestibulo-ocular reflex was more pronounced immediately after orbital spaceflight than in control. An analogous alteration in the otolith reflex was observed in most cosmonauts after short-time space missions. In adult terrestrial vertebrates, as well as in humans, immediately after landing there was found a drop in the level of activity and deterioration of the equilibrium function and motor coordination. Another interesting finding was an unusual looping behavior when fish and tadpoles swam in loops post landing. Presumably, unusual motor activity of animals, as well as illusions arising in cosmonauts and astronauts during the transition from 1 to 0 g, have the same background being associated with changes in the stimulation pattern of the otolith organs. Considering the similarity of vestibular responses, the use of animal models seems very promising as allowing different invasive techniques.     

Resistance and hemodynamic reactions in healthy pilots under the conditions of passive orthostatic loading

The results of the analysis of materials on the expert assessment of 66 healthy pilots subjected to a passive orthostatic stress test (POT) by the generally accepted technique of a 20-min head-down tilt bed rest at an angle of 80° to the horizontal are presented. The obtained hemodynamic responses to the test were typified using the generally accepted concepts of functional classes (FC). A good POT tolerance was recorded in 86.4% of the observations, with 36.4% assigned to the first functional class (FC-I) and 50%, to the second functional class (FC-II). A satisfactory orthostatic test tolerance (FC-III) was recorded in 10.6% of the observations, whereas a reduced and poor tolerance (FC-IV and FC-V) was found in 3% of the observations. According to ECGs and computer-assisted tachooscillography, subjects of the FC-I group reached the optimum indicators in their adaptive hemodynamic responses, compared to the pilots of the FC-II group and, particularly, the FC-III group. The latter two groups were found to exhibit some previously unknown objective symptoms, such as marked blood pressure (BP) lability and reversible hypo- and hypertensive responses, which allowed us to differentiate the FC-I pilots from the latter two groups. Based on the obtained results, additional clinical functional tolerance assessment criteria have been developed for a passive orthostatic test as part of the medical expert assessment of flight personnel with different levels of functional stability.     

Salt-induced folding of a rabbit muscle pyruvate kinase intermediate at alkaline pH

The effect of alkaline denaturation on the structural and functional characteristics of rabbit muscle pyruvate kinase (PK) was investigated using enzymatic activity measurements and a combination of optical methods such as circular dichroism, fluorescence, and ANS binding. At a critical pH, 10.5, PK exists in an intermediate state (alkaline unfolded state) with predominant secondary structure along with some of the tertiary interactions and a strong binding to the hydrophobic dye ANS. This intermediate retains the enzymatic activity and corresponds to a dimeric state of the molecule. Above pH 10.5, a sudden fall in the spectral properties and enzymatic activity occurs suggesting the dissociation of the molecule followed by unfolding at very high pH. Addition of salts such as NaCl, KCl, and Na₂SO₄ to the alkali-induced state induces both secondary and tertiary structure to a level equivalent to that of native tetramer (salt-induced state). Chemical- and temperature-induced unfolding of the alkali-induced state as well as the salt-induced refolded state of PK reveal the presence of intermediate conformations in the unfolding pathway. The unfolding transition curves are noncoinciding and noncooperative along with ANS binding at intermediate concentrations of denaturants during unfolding. The observations presented in this paper suggest that the native pyruvate kinase tetramer dissociates to an active dimer around pH 10.5 and further to inactive monomer before attaining a completely unfolded monomeric conformation.     

The features of lipid peroxidation and the antioxidant system of blood under the influence of different concentrations of nitric oxide in a chronic experiment

This paper presents the results of the study of oxidative metabolism of the blood of intact animals subjected to prolonged exposure to nitric oxide at concentrations of 20, 50, and 100 ppm. The experiment was carried out with Wistar rats. NO inhalation was performed for 30 days. The state of blood oxidative metabolism was evaluated after inhalation and a 30-day-long recovery period after discontinuation of NO oxidative stress. The intensity of lipid peroxidation was studied in plasma and erythrocytes by induced biochemiluminescence and the measurement of the level of malondialdehyde. The activity of superoxide dismutase was determined in the hemolysate of erythrocytes. It was established that the optimal dose of inhaled NO is 20 ppm: a maximum increase in the total antioxidant activity after 30 days and normalization of lipid peroxidation in the blood after the completion of the recovery period were observed at this concentration. High concentrations of nitric oxide (50 and 100 ppm) initiated lipid peroxidation in erythrocytes and plasma after discontinuation of NO oxidative stress (after the completion of the recovery period) thus enhancing catalytic properties of superoxide dismutase.     

Evaluation of stress induced by flight activity by measuring the hormonal response

The aim of the present study was to quantitatively investigate the different levels of adaptation to glight and to evaluate the hormonal respone to flight activity as a possible reliable tol to quantify the level of stress induced by flight. The hormonal response of growth hormone (GH), cortisol, and prolactin (PRL) to flight activity was evaluated in a group of student pilots (n=11; all male; age 20±2 years) and flight instructors (n=11; all male; age 27±2 years) of an Italian Air Force flight school. Blood samples were obtained immediately before and after a training flight session. Hormonal determination by RIA technique after flight showed a significant increase of plasma hormonal levels of GH, PRL, and cortisol in the students. Conversely, in the instructors only GH showed a significant increase versus preflight values, whereas PRL and cortisol did not show significant differences. Moreover, preflight hormonal levels of GH and PRL were significantly higher for student pilots compared to the same values for flight instructors. The data lead to establishing a close correlation between the hormonal response to flight activity and the level of tolerance and adaptation to flight-induced stress.This study was in part presented as an oral communication to the 62nd Meeting of the Aerospace Medical Association. (Farrace, S. et al., Aviation Space and Environmental Medicine 1992; 63(5):Abstract 413). We gratefully acknowledge Mr. Paul Codley for reviewing the English version.     

Functional diversity changes of microbial communities along a soil aquifer for reclaimed water recharge

The physiochemical and functional diversity of soil-attached microorganisms was investigated using a stabilized laboratory-scale soil aquifer treatment (SAT) system. In this system, reclaimed water after ozonation was used as the feed water, and 60% dissolved organic carbon was removed by the unsaturated vadose layer in 0.8?days. Soil biomass (volatile solids, phospholipid extraction) and functional diversity significantly decreased from the unsaturated vadose layer to the saturated aquifer, where they maintained the same level. Using principal components analysis based on substrate utilization pattern, the vadose layer soil sample was clearly separated from the saturated layer samples. Exceptionally, the oxidation rates of esters remained stable during SAT, indicating the purification potential on certain recalcitrant organic compounds in the saturated aquifer given an adequate retention time. Correlation analysis revealed that organic carbon was the key limiting factor for microbial biomass and activity, especially for tyrosine-like aromatic proteins and soluble microbial byproduct-like materials.     

Potential Sequential Exposures to 2-Butoxyethanol After Use of a Hard-Surface Cleaner

Professional workers and consumers frequently use hard-surface cleaning products and these products may contain glycol ethers (GEs), such as 2-Butoxyethanol (2-BE). Governmental agencies have set exposure limits for some chemicals used in cleaning products and these exposure limits have been used as guides to protect human health. The study objectives were to determine realistic inhalation exposures for professional workers performing multiple, sequential cleaning tasks and compare the exposures to the acute reference exposure level (REL), which California established for 2-BE. The ConsExpo model was acceptable for evaluating exposure based on a comparison of its predictions to experimentally measured 2-BE vapor concentrations from hard-surface cleaning. The typical worker exposure was predicted for a cleaning scenario consisting of three bathrooms and three kitchens (or three bedrooms) in a 1-h period. This exposure scenario would not be expected to result in significant health consequences because the predicted exposure was much lower than the REL. The predicted chronic and aggregate exposures were also acceptable. This analysis identified two important variables that affect inhalation exposure: cleaners should be used with adequate ventilation and wet wiping towels should be properly disposed so that they are not a source of continuing exposure.     

A study of the hygienic aspects of the pedagogic process

A knowledge of the laws governing changes in the functional state of the organism of pupils during lessons at school is one of the principal bases for solving the hygienic problems of organizing the teaching. The main concern is the dynamics of changes in the actual functional state of the CNS as a result of a whole complex of endogenous and exogenous factors as well as the school work of the pupil itself. Changes in the functional state of the optic and acoustic analysors deserve special attention in this respect because of their great exposure in pedagogical work. The existing interindividual differences in performance and in the work rate of pupils should be solved by an adequate pedagogical approach. Correct use of the principle of differentiated tuition can be a positive contribution to solving some of the topical problems of hygiene of the pedagogical process.