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At least 1,135 records · Page 63Linked to original sources
PubMed2004

Space Station Biological Research Project (SSBRP) Cell Culture Unit (CCU) and incubator for International Space Station (ISS) cell culture experiments.

The CCU and Incubator are habitats under development by SSBRP for gravitational biology research on ISS. They will accommodate multiple specimen types and reside in either Habitat Holding Racks, or the Centrifuge Rotor, which provides selectable gravity levels of up to 2 g. The CCU can support multiple Cell Specimen Chambers, CSCs (18, 9 or 6 CSCs; 3, 10 or 30 mL in volume, respectively). CSCs are temperature controlled from 4-39 degrees C, with heat shock to 45 degrees C. CCU provides automated nutrient supply, magnetic stirring, pH/O2 monitoring, gas supply, specimen lighting, and video microscopy. Sixty sample containers holding up to 2 mL each, stored at 4-39 degrees C, are available for automated cell sampling, subculture, and injection of additives and fixatives. CSCs, sample containers, and fresh/spent media bags are crew-replaceable for long-term experiments. The Incubator provides a 4-45 degrees C controlled environment for life science experiments or storage of experimental reagents. Specimen containers and experiment unique equipment are experimenter-provided. The Specimen Chamber exchanges air with ISS cabin and has 18.8 liters of usable volume that can accommodate six trays and the following instrumentation: five relocatable thermometers, two 60 W power outlets, four analog ports, and one each relative humidity sensor, video port, ethernet port and digital input/output port.

Automation↗
PubMed2005

G tolerance and pulmonary effects of removing chest counterpressure during pressure breathing.

BACKGROUND: In agile fighter aircraft positive pressure breathing is commonly used as part of the anti-G ensemble. To optimize G protection and prevent over-distention of the lungs, increased airway pressure is balanced by applying a counterpressure to the chest. The aim was to investigate the efficacy of chest counterpressure. METHODS: Three series of experiments were performed using the anti-G ensemble of the 39 Gripen aircraft (AGE-39) and exposing the subjects to 20-s G time profiles; in the first (n = 12) up to +8.0 Gz, in the second (n = 9) up to + 9.0 Gz, and also to simulated aerial combat maneuvers (SACM). Central and peripheral vision, arterial and airway pressures, pressure in the lower portion of the esophagus, and chest wall distension were measured. In the third series, six subjects were exposed to up to +7.0 Gz and esophageal pressure was measured in the upper thorax. In all series, two conditions were compared: with and without pressurized chest bladder. RESULTS: During the 20-s profiles arterial and esophageal pressures, chest wall distension, and visual impairment were similar with and without pressurized chest bladder. Upper esophageal pressure was slightly higher by 10-24% with than without chest bladder (p = 0.03). During SACM, time to exhaustion and the level of perceived exertion were similar with and without pressurized chest bladder. SUMMARY: The results suggest that the chest counterpressure can be removed from the AGE-39 without diminishing G tolerance or G endurance or significantly increasing the risk of lung parenchyma disruption.

Adult↗
PubMed2005

[Effects of dilution rates on the oscillatory behaviors of a very high gravity continuous ethanol fermentation system].

Continuous ethanol fermentation using very high gravity medium containing 280 g/L glucose, 5 g/L yeast extract and 3 g/L peptone was run at the dilute rates of 0.006 h(-1), 0.012 h(-1), 0.017 h(-1), 0.024 h(-1) and 0.032 h(-1) (based on the total working volume) in a combined bioreactor system composed of a stirred tank and three-stage tubular bioreactors in series. Oscillations marked by big fluctuations of residual glucose, ethanol and biomass were observed at the dilution rate of 0.012 h(-1). The Hopf Bifurcation theory was used to analyze and predict the occurring of these oscillations and the dilution rates that incited oscillations. Theoretical analysis revealed that oscillations can occur at designated specific growth rates and was validated by experimental results. The benefits of oscillations for the fermentation system were also discussed by comparing the fermentation results with those without oscillations.

Bioreactors↗
PubMed2004

The mechanism [correction of mehanism] of spatial [correction of spetial] orientation in conditions of G-stress.

Six test subjects were subjected to lateral (+Gy) and longitudinal-lateral (+Gz/+Gy) accelerations in a centrifuge with a rotation radius of 6.55 m. During rotation, test subjects were instructed to indicate the position of subjective visual vertical. Results of this study demonstrated that during exposure to +Gy and +Gz/+Gy accelerations, the direction of the indicated subjective vertical approached the direction of the resultant acceleration vector when the lateral component increased. This observed effect decreases with an increase of the longitudinal component of the acceleration. It was suggested that exposure to (i.e. "pulling") high lateral acceleration (up to 2-3 Gy) in highly maneuverable aircraft can hinder spatial orientation of a pilot due to this persistent illusory spatial position as reported above. Our analysis showed that the process of spatial orientation under the conditions of G-load influence becomes more difficult and it is depending on the compromise between visual and vestibular-proprioceptive inputs. On account of this finding, it may be proposed that under conditions of G-load influence, pilots that rely primarily on visual perception may be exposed to higher risk of spatial disorientation.

Acceleration↗
PubMed2004

The G-tolerance after pharmacological hypohydration.

A group of 18 healthy male subjects (25-45 y.o.) participated in the studies of +8.3 Gx tolerance (profile of ballistic reentry) and +Gz tolerance (up to physiological limit) before and after pharmacological hypohydration of organism. Moderate hypohydration was carried out by one 40 mg Furosemid (Lasix) dose, or by pharmacological complex: Furosemid (40 mg) + Hypothiazide (25 mg) + Triamteren (50 mg). Subjects removed with urine about 2 l of water, that was accompanied by increase excretion of electrolytes and caused reduction of the body mass by 2.0 +/- 0.2% and diminution of the plasma volume by 13.5% +/- 2.0%. Pharmacological hypohydration does not lead to a substantial loss in +Gx tolerance. No pathological signs, limiting +Gx tolerance up to 8.3 g were found. The longitudinal +Gz tolerance was less, than +Gx one. The limit of achieved +Gz loads after diuretics reduced by 0.6 g. The scientific and applied significance of this research is that diuretics can be safety used in pre-launch period to prevent the negative effects associated with initial phase of space flight. Besides the preliminary intake of diuretics promotes to diminish of discomfort of cosmonauts, reducing urination in a period of prelaunch waiting in spacecraft.

Adaptation, Physiological↗
PubMed2004

Influence of gravity changes induced by parabolic flight on cytokine production in mouse spleen.

Dysregulation of the immune system has been a well-documented effect of human exposure to a microgravity environment during space flight. These effects have included altered cytokine production, reduced proliferative responses, altered signal transduction pathways and altered distribution of peripheral immune cells. Recent reports have documented immunologic studies performed in-flight. When tested during space flight, delayed-type hypersensitivity was reduced, indicating a dysregulation of cell-mediated immune function. However, the mechanisms by which this occurs remain unclear. The production of cytokines plays a critical role in the ability of a host to mount an immune response against an invading microorganism. In this study, the alteration of cytokine responses in mice following parabolic flight (PF) was investigated.

Animals↗
PubMed2004

Lipid peroxidation and the system of antioxidant defence in humans after hypergravitational influence.

Hypergravitational influence (HI) +Gz (head-pelvis) within ranges of up to 3, up to 5, and up to 7 g with an acceleration speed of 0.03 g/s was applied to a group of men of an age of 25 to 45 y.o. In their blood serum the parameters of lipid peroxidation (LP) and the system of antioxidant defence (AOD) had been studied. HI results in LP intensity changing in a human body. HI increasing caused an increase in a number of AOD components involved in the free radical processes (FRP) compensation and functioning in a water phase. The characteristics of AOD lipid-phase link does not change. The mechanisms of compensating and monitoring of FRP intensity at HI required further studies.

Adult↗
PubMed2004

Brief exposure to -2 Gz reduces cerebral blood flow velocity during subsequent +2 Gz acceleration.

In order to determine the implication of the cerebral vasoconstriction occurring under -Gz acceleration in the mechanism of the push-pull effect, four healthy male non-pilots were submitted to a control centrifugation at +2 Gz, and then to an experimental run with identical +2 Gz plateau, but preceded by -2 Gz exposure. Cerebral blood flow velocity (CBFV), pulsatility index, and resistance index (RI) were continually measured with a transcranial Doppler instrument. The decrease in blood pressure and in CBFV was more important during the experimental run, when the change in RI was not different. We concluded that the cerebral vasoconstriction occurring under -2 Gz exposure seems not to be a major contributor in the mechanism of the push-pull effect appearing during subsequent +2 Gz acceleration.

Blood Pressure↗
PubMed2004

Hydromechanic effects of rotations on human blood vessels on a short-radius centrifuge.

An "imitation" task of evaluating the adequacy of model gravitation (SRC) and natural one with consideration of the distribution of liquid environment in human lower extremities (interval evaluation) has been formulated and solved. A reversed "imitation" task of calculating the SRC rotation frequency with consideration of a patient's individual height on the basis of zero difference on the criterion suggested. The methods developed were realized in a doctor's interface that provides a mode of a calculation experiment. Probation on real information showed great possibilities of using the interface as a technical means for a doctor to solve tasks of cosmic medicine, traumathology and orthopedics.

Aerospace Medicine↗
PubMed2004

Load-dependent regulation of neuromuscular system.

Roles of gravitational loading, sarcomere length, and/or tension development on the electromyogram (EMG) of soleus and afferent neurogram recorded at the L5 segmental level of spinal cord were investigated during parabolic flight of a jet airplane or hindlimb suspension in conscious rats. Both EMG and neurogram levels were increased when the gravity levels were elevated from 1-G to 2-G during the parabolic flight. They were decreased when the hindlimbs were unloaded by exposure to actual microgravity or by suspension. These phenomena were related to passive shortening of muscle fibers and/or sarcomeres. Unloading-related decrease in sarcomere length was greater at the central rather than the proximal and distal regions of fibers. These activities and tension development were not detected when the mean sarcomere length was less than 2.03 micrometers. It is suggested that load-dependent regulation of neuromuscular system is related to the tension development which is influenced by sarcomere length.

Animals↗
PubMed2004

Mechanisms of the gravitational sensitivity of cells.

It is well known that specialized gravireceptory cells have been formed in the course of evolution in the majority of multicellular organisms. These are statosytes (statenchyme cells) in higher plants and otolith apparatus cells in animals. The mechanisms of gravity reception and the generation of gravitational stimuli in these cells are well understood. Therefore, our attention was focused on cells devoid of special gravireceptory mechanisms, namely cell cultures grown in vitro (fibroblasts and osteoblasts) and unicellular free-swimming (i.e. possessing a locomotor apparatus) organisms. These were mainly representatives of two classes: Ciliata and Flagellata. The choice of the objects of study was mainly determined by their ecological and physiological characteristics with the main goals of this work.

Animals↗
PubMed2004

Association between gravitational force and tissue metabolism in periparturient rats.

Recently, interest in mammalian reproduction and offspring survival in altered gravity has been growing. Because successful lactation is critical for mammalian neonate survival, we have been studying the effect of gravity metabolism. We have shown an exponential relationship between glucose metabolic rate in mammary tissue of periparturient rats and an increase in gravity load. In this study we showed that changes in mammary metabolic rate due to gravity force were accompanied by a decrease in glucose metabolism in adipose tissue and by a reduced size of adipocytes. We assume that these changes are likely due to changes in prolactin or leptin levels related to altered gravity load.

Adipocytes↗
PubMed2004

Development of medical control of man in conditions of +Gz accelerations at short-arm centrifuge.

To develop a program of on-line medical monitoring of human subjects during rotation on a short-arm centrifuge (SAC), which is viewed as a promising method of providing artificial gravity, 153 runs were performed with participation of 17 subjects exposed to +Gz at 0.8, 1.2 and 1.6 G up to 40 minutes 3 times a day over a 3-d cycle. It was found that the on-line medical monitoring program for humans exposed to SAC +Gz loads should include recording of the system blood circulation and local circulation in head and leg vessels.

Acceleration↗
PubMed2004

Feasibility of real-time 3D echocardiography in weightlessness during parabolic flight.

Aim of the study was to test the feasibility of transthoracic real-time 3D (Philips) echocardiography (RT3D) during parabolic flight, to allow direct measurement of heart chambers volumes modifications during the parabola. One RT3D dataset corresponding to one cardiac cycle was acquired at each gravity phase (1 Gz, 1.8 Gz, 0 Gz, 1.8 Gz) during breath-hold in 8 unmedicated normal subjects (41 +/- 8 years old) in standing upright position. Preliminary results, obtained by semi-automatically tracing left ventricular (LV) and left atrial (LA) endocardial contours in multiple views (Tomtec), showed a significant (p<0.05) reduction, compared to 1 Gz, of LV and LA volumes with 1.8 Gz, and a significant increase with 0 Gz. Further analysis will focus on the right heart.

Adult↗
PubMed2004

Contemporary conception of anti-G protection of cosmonauts in flights aboard "Soyuz" space vehicles.

To ensure safety of cosmonauts impacted by +Gx loads during insertion into orbit of a Soyuz-type space vehicle, it is critical to conduct appropriate medical selection of candidates to space flights, to give them proper complete physical and specialized centrifuge training, and to make it sure that at the moment of actual injection the cosmonaut's posture is optimal relative to the g-vector and that the body is tight fitting the custom-molded couch. No AGS is needed. For the purposes of protection of cosmonauts descending in the Soyuz vehicles, vital are countermeasures applied in the course of flight, water-salt supplements on the descent day, and the optimal posture, an anti-g suit, and a custom-molded couch with an additional body-restraint system and dampers used on the phase of reentry.

Acceleration↗
PubMed2004

Testing method of plus and minus Gz tolerance at Czech Air Force pilots.

Pilots' physiological measurement in conditions of alternating plus and minus Gz (gravitational acceleration) has been done during real flights. The comparison of physiological responses during flights at the safe altitude of 7000 ft and low level flights at the altitude of 900 ft over ground bears on the evaluation of changes of the continuous blood pressure and the heart rate. High level of pilots' plus-minus Gz tolerance is essential requirement to cope with low level flights in agile aircraft. It was proved that the sinusoidal profile during real flights is possible to use for pilots' tolerance to plus and minus Gz load evaluation. A system for the physiological signal acquisition in a cockpit of combat aircraft was developed for this purpose.

Acceleration↗
PubMed2004

Effect of centrifuge-induced artificial gravity and ergometric exercise on cardiovascular deconditioning, myatrophy, and osteoporosis induced by a -6 degrees head-down bedrest.

We have reported that centrifuge-induced artificial gravity with ergometric exercise could reduce developing cardiovascular deconditioning in humans. In the present study, we examined this load could prevent the myatrophy and osteoporosis induced by head-down bedrest for 20 days. Subjects were ten healthy male volunteers with informed consent. They were requested to lie down at -6 degrees for 20 days, and evaluation for cardiovascular deconditioning, myatrophy, and osteoporosis. As the result, high G-load with low intensity exercise suppressed the orthostatic intolerance and increase in serum osteoporotic marker, whereas low G-load with high intensity ergometric exercise maintained the maximal oxygen intake, heart dimension, and prevented myatrophy. The combination of high/low G-load with low/high intensity exercise will determine the optimal protocol for prevention of cardiovascular deconditioning, myatrophy, and osteoporosis.

Adult↗