CONTENTS
Experimental and Theoretical Investigations
Mitrikas V.G. Estimation of ionizing radiation effective doses in the International space station crews by the method of calculation modeling
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 5-11
Monitoring of the radiation loading on cosmonauts requires calculation of absorbed dose dynamics with regard to the stay of cosmonauts in specific compartments of the space vehicle that differ in shielding properties and lack means of radiation measurement. The paper discusses different aspects of calculation modeling of radiation effects on human body organs and tissues and reviews the effective dose estimates for cosmonauts working in one or another compartment over the previous period of the International space station operation. It was demonstrated that doses measured by areal or personal dosimeters can be used to calculate effective dose values. Correct estimation of accumulated effective dose can be ensured by consideration for time course of the space radiation quality factor.
Key words: space ionizing radiation, effective dose, quality factor.
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Ivanov À.À., Dorozhkina Î.V., Lyakhova Ê.N., Bulynina Ò.Ì., Abrosimova À.N., Severyukhin Yu.S., Gaevsky V.N., Molokanov À.G., Ushakov I.B., Krasavin Å.À. Immediate radiobiological effects in mice following γ-irradiation by low doses
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 12–18
Outbred CD-1 mice females aged 4 to 4.5-months were investigated in 21–22 hours following total γ-irradiation at 10, 25, 50, 75, 100 and 200 mGy. Loss in bone marrow karyocytes, as well as spleen and thymus mass reductions were significant in the group of animals irradiated at 50 and 200 mGy and less dramatic in mice irradiated at 75 mGy. The orientative-trying behavior reaction (OTBR) in the open field tested in 19–20 hours after exposure to 10 and 25 mGy was reliably stronger than in the group of biological control; however, emotional status (ES) in the animals that received 10 mGy dropped significantly. Mice irradiated at 50 mGy were found to weaken the grip of their front limbs. Dose levels differing in opposite radiobiological effects on the parameters under study were established. Doses in the range from 10 to 25 mGy maximized OTBR and ES, while doses of 50, 100 and 200 mGy produced high reactions of the immune and hemopoietic organs.
Key words: γ-radiation, small dose, bone marrow, thymus, spleen, leukocytes, open field test, spontaneous motor activity, physical ability, radiosensitivity, radioresistance.
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Kuzichkin D.S., Markin À.À., Vorontsov À.L., Morukov B.V., Zhuravleva Î.À., Zabolotskaya I.V., Vostrikova L.V. Comprehensive assessment of the hemostasis system in test-subjects in experiment «Mars-500»
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 19–24
The paper is devoted to the håmostasis studies in the course of long-term (520 d) isolation in an airtight chamber. Measured parameters included activated partial thromboplastin time (APTT), international normalized ratio (INR), thrombin time (ÒT); concentrations of fibrinogen (FBG), plasminogen (PG), Willebrand factor (WF), tissue factor pathway inhibitor (TFPI), and tissue plasminogen activator (TPA), thrombomodulin (ÒÌ); activities of the coagulation cascade factors (II, V, VII, X, VIII, IX, XI, XII), antithrombin III (ATIII), protein Ñ (PC), Ñ1-inhibitor (Ñ1), ?2-antiplasmin (ÀP), TPA and TFPI.
The investigation revealed a diversity of changes in the plasma fibrinogen concentration, slower blood coagulation in the intrinsic pathway and the final stage, and a relative rise in the activities of ATIII and PC-inhibited factors. The rest parameters showed different trends.
Key words: håmostasis, blood coagulation factors, isolation in airtight chamber.
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Kuznetsova G.D., Gabova A.V., Lazarev I.E., Obukhov Yu.V., Obukhov K.Yu., Morozov A.A., Kulikov M.A., Shchatskova A.B., Vasilieva O.N. Tomilovskaya E.S. Frequency-temporal structure of human electroencephalogram in the condition of artificial hypogravity: dry immersion model
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 25–32
Frequency-temporal electroencephalogram (EEG) reactions to hypogravity were studied in 7 male subjects at the age of 20 to 27 years. The experiment was conducted using dry immersion (DI) as the best known method of simulating the space microgravity effects on the earth. This hypogravity model reproduces hypokinesia, i.e. the weight-bearing and mechanic load removal, which is typical of microgravity.
EEG was recorded by Neuroscan-2 (Compumedics) before the experiment (baseline data) and at the end of day 2 in DI.
Comparative analysis of the EEG frequency-temporal structure was performed with the use of 2 techniques: Fourier transform and modified wavelet analysis. The Fourier transform elicited that after 2 days in DI the main shifts occurring to the EEG spectral composition are a decline in the alpha power and a slight though reliable growth of theta power. Similar frequency shifts were detected in the same records analyzed using the wavelet transform. According to wavelet analysis, during DI shifts in EEG frequency spectrum are accompanied by frequency desorganization of the EEG dominant rhythm and gross impairment of total stability of the electrical activity with time. Wavelet transform provides an opportunity to quantify changes in the frequency-temporal structure of the electrical activity of the brain. Quantitative evidence of frequency desorganization and temporal instability of EEG wavelet spectrograms may be the key to the understanding of mechanisms that drive functional disorders in the brain cortex in the conditions of hypogravity.
Key words: model of hypogravity, dry immersion, human electroencephalogram, Fourier transform, EEG wavelet transform.
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Sun I., Voronkov Yu.I., Ardashev V.N., Glukhova S.I. Heart rhythm variability analysis and assessment of the spinal pain syndrome during dry immersion
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 33–37
The spinal pain syndrome appears in cosmonauts on both short and long-duration missions. This untoward factor may affect body systems functioning and complicate the successful accomplishment of space mission.
Purpose of the investigation was to examine the lumbar spine and to elucidate whether its condition relates to the spinal pain development and changes in heart rate variability (HRV) in the microgravity environment. The experiment was conducted in dry immersion as a method of microgravity effects simulation. It was shown that in dry immersion locomotion reproduces the patterns peculiar for significant gravitational unloading.
Spinal pain intensity, angles and heights of the lumbar intervertebral discs and HRV were measured in 19 selected volunteers. During the experiment, all the volunteers developed pains in the back that abated gradually. Pain dependence on the height of intervertebral discs and cardiac regulatory mechanisms were investigated.
Key words: dry immersion, pain in the back, heart rhythm variability, electrocardiogram dispersion mapping.
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Dyachenko A.I., Ermolaev E.S., Shulagin Yu.À., Goncharov À.Î., Suvorov À.V. Experimental and theoretical studies of human hypercapnic ventilatory response with the use of mathematical gas exchange modeling
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 38–43
A mathematical model of biotechnical system integrating the human cardiorespiratory system with hard- and software was designed to investigate breathing control. The model describes dynamics of carbon dioxide and oxygen in 3 biotechnical system compartments in the course of rebreathing tests. The tests do not require tanks with compressed gas and, therefore, can be performed in space flights. Results of simulated modeling of the ventilation response in 2 breath tests, i.e. to hypercapnia due to rebreathing of a hyperoxic gas mixture and to hypercapnia combined with hypoxia due to air rebreathing, are presented. Model validity was verified by comparison of the modeling and experimental data. The mathematical model made it evident that CO2 partial pressures in tissues, lungs and the breathing circuit equalize very fast when initial carbon dioxide concentration in the respiration circuit is equal to the end-tidal CO2 concentrations in man at rest.
Key words: respiration control, hypercapnic and hypoxic ventilatory response, mathematical gas exchange modeling, rebreathing test.
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Vorozhtsova S.V., Bulynina Ò.Ì., Molokanov À.G., Ivanov À.À. Cysteamine-induced modification of cytogenetic damages to the corneal epithelium of mice exposed to corpuscular radiation with varying linear transfer energies
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 44–50
Cytogenetic damages to cells of the corneal epithelium were studied in mice exposed to protons (10, 25, 50 and 645 MeV), ions of boron, carbon and neon, and X-rays (180 keV) within the dose range from 25 to 750 cGy and injected with a radioprotector. Animals were subjected to a single exposure. The protective effect of ß-mercaptoethylamine was tested in the experiment. The radioprotector (0.2 ml) was introduced intraperitoneally 30 minutes before exposure in 350 ml/kg dose. Control animals received the same amount of sodium chloride solution. The animals were sacrificed by cervical dislocation in 24 and 72 hrs. after exposure. It was shown that cysteamine effectively protects in vivo corneal epithelium cells of mice exposed to electromagnetic radiation or protons in a broad energy spectrum (10 to 645 MeV), and to a broad range of radiation doses (25 to 750 cGy), as judged from levels of aberrant mitosis and mitotic activity. The radioprotector exhibited the highest effectiveness in animals exposed to the doses of 50 to 300 cGy. These findings prove that cysteamine may potentially be used for pharmacological protection from protons. The radioprotector failed to prevent chromosomal aberrations after exposure to heavy charged particles of boron, carbon and neon, which implies the need to design radioprotectors against this type of corpuscular radiation specifically.
Key words: corneal epithelium, protons, ions of boron, carbon, neon, mitotic index, chromosomal aberrations, ß-mercaptoethylamine, cysteamine, changed dose factor.
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Pashchenko P.S., Risman B.V. Morphological aspects of changes in the spinal gray matter due to
g-loads in experiment
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 51–55
To study changes in spinal cord structures brought about by g-loads, laboratory animals (rats) were rotated on a centrifuge following a special procedure. Systematic g-loads along the craniocaudal axis resulted in reactive alterations, and also obvious destructive processes in the spinal gray matter (SGM). Light optical microscopy discovered that part of neurons had bodies with less intensive dying. Electron microscopy showed that among the cytoplasmic structures mitochondria were particularly sensitive to g-loads, which could affect mitochondrial oxidation. In the lumbar, these changes were observed in every segment under study; they were more significant in comparison with those found in cervical and thoracic segments of the spinal cord. Interneuron disintegration at neural centers revealed itself by the «light» type degeneration of synapses. Changes in capillaries included nuclei deformations and destruction of organelles in endotheliocytes, pericapillary edema, and erythrocytes sludge in the lumen. Inequality of spinal cord changes suggests the mosaic pattern of their distribution. Furthermore, their manifestation grew with the cranicaudal gradient so that the most conspicuous destructive developments occurred in the lumbar but not in the thoracic let alone the cervical segment. Acute g-loads gave rise to reactive changes in neurons and interneuron synapses that were the morphological markers of increased functional activity of neurons and activation of interneuron firing. In addition to the reactive changes, chronic g-loading also produced destructive disorders in GSM structures. These changes were not observed following acute g-loads and, therefore, resulted from multiple g-exposures and were cumulative.
Key words: gravity, g-loads, spinal cord, anterior horns.
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Brief Communications
Protasova Î.V., Maksimova I.À., Morukov B.V., Protasov S.V., Ushakov I.B. Investigation of iron, zinc, stable strontium and lithium content in biological fluids and tissues during experimental space flight simulation
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Aviakosmicheskaya i Ekologicheskaya Meditsina (Russia). 2015. V. 49. ¹ 3. P. 56–60
In an experiment with space flight simulation, atomic emission spectral analysis with inductively coupled argon plasma was employed to measure iron, zinc, stable strontium and lithium in blood serum and its ultrafiltered fraction, and excretion with daily urine and hair. Monitoring of serum iron and its ultraviolet fraction showed good balance of these parameters in all periods of the experiment. Blood serum was found to contain exclusively iron bound with protein carriers. In the experiment, serum zinc was distinctively dependent on the nutrient status. Stable strontium excretion with daily urine can be a biological indicator of its homeostasis.
The experiment factors had no effect on the lithium form in serum, i.e. lithium was invariably present in the ionized form and in quantities equal to ultrafiltered lithium in all blood samples in all periods of the experiment.
Key words: zinc, iron, stable strontium, lithium, experimental simulation of space flight.
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Chronicles and Information
Belakovsky Ì.S. The 6th International congress «Medicine in space and extreme environments»
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