Hypergravity
Weightlessness
Gravitation
Hypogravity
Weightlessness Simulation
Centrifugation
Gravity, Altered
Weightlessness Countermeasures
Gravity Suits
Dispersion of 0.5- to 2-micron aerosol in microG and hypergravity as a probe of convective inhomogeneity in the lung. (1/95)
We used aerosol boluses to study convective gas mixing in the lung of four healthy subjects on the ground (1 G) and during short periods of microgravity (microG) and hypergravity ( approximately 1. 6 G). Boluses of 0.5-, 1-, and 2-micron-diameter particles were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 150 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The dispersion, deposition, and position of the bolus in the expired gas were calculated from these data. For each particle size, both bolus dispersion and deposition increased with Vp and were gravity dependent, with the largest dispersion and deposition occurring for the largest G level. Whereas intrinsic particle motions (diffusion, sedimentation, inertia) did not influence dispersion at shallow depths, we found that sedimentation significantly affected dispersion in the distal part of the lung (Vp >500 ml). For 0.5-micron-diameter particles for which sedimentation velocity is low, the differences between dispersion in microG and 1 G likely reflect the differences in gravitational convective inhomogeneity of ventilation between microG and 1 G. (+info)Hypergravity stimulates collagen synthesis in human osteoblast-like cells: evidence for the involvement of p44/42 MAP-kinases (ERK 1/2). (2/95)
The formation and organization of skeletal tissue is strongly influenced by mechanical stimulation. There is increasing evidence that gravitational stress has an impact on the expression of early response genes in mammalian cells and may play a role in the formation of extracellular matrix. In particular, osteoblasts may be unique in their response to gravitational stimuli since in these cells microgravity has been reported to reduce collagen synthesis, while in fibroblasts the opposite effect was observed. Here, we have investigated the influence of hypergravity induced by centrifugation on the collagen synthesis of human osteoblast-like cells (hOB) and studied the possible involvement of the mitogen-activated protein (MAP) kinase signaling cascade. Collagen synthesis was significantly increased by 42+/-16% under hypergravity at 13 x g, an effect paralleled by the enhanced expression of the collagen I alpha 2 (COL1A2) mRNA. No difference was seen in the proportion of collagen types I, III, and V synthesized by hOB. Hypergravity induced a markedly elevated phosphorylation of the p44/42 MAP kinases (ERK 1/2). The inhibition of this pathway suppressed the hypergravity-induced stimulation of both collagen synthesis as well as COL1A2 mRNA expression by about 50%. Our results show that the collagen synthesis of non-transformed hOB is stimulated under hypergravitational conditions. This response appears to be partially mediated by the MAP kinase pathway. (+info)The gravity field of Mars: results from Mars Global Surveyor. (3/95)
Observations of the gravity field of Mars reveal a planet that has responded differently in its northern and southern hemispheres to major impacts and volcanic processes. The rough, elevated southern hemisphere has a relatively featureless gravitational signature indicating a state of near-isostatic compensation, whereas the smooth, low northern plains display a wider range of gravitational anomalies that indicates a thinner but stronger surface layer than in the south. The northern hemisphere shows evidence for buried impact basins, although none large enough to explain the hemispheric elevation difference. The gravitational potential signature of Tharsis is approximately axisymmetric and contains the Tharsis Montes but not the Olympus Mons or Alba Patera volcanoes. The gravity signature of Valles Marineris extends into Chryse and provides an estimate of material removed by early fluvial activity. (+info)Altered gravity downregulates aquaporin-1 protein expression in choroid plexus. (4/95)
Aquaporin-1 (AQP1) is a water channel expressed abundantly at the apical pole of choroidal epithelial cells. The protein expression was quantified by immunocytochemistry and confocal microscopy in adult rats adapted to altered gravity. AQP1 expression was decreased by 64% at the apical pole of choroidal cells in rats dissected 5.5-8 h after a 14-day spaceflight. AQP1 was significantly overexpressed in rats readapted for 2 days to Earth's gravity after an 11-day flight (48% overshoot, when compared with the value measured in control rats). In a ground-based model that simulates some effects of weightlessness and alters choroidal structures and functions, apical AQP1 expression was reduced by 44% in choroid plexus from rats suspended head down for 14 days and by 69% in rats suspended for 28 days. Apical AQP1 was rapidly enhanced in choroid plexus of rats dissected 6 h after a 14-day suspension (57% overshoot, in comparison with control rats) and restored to the control level when rats were dissected 2 days after the end of a 14-day suspension. Decreases in the apical expression of choroidal AQP1 were also noted in rats adapted to hypergravity in the NASA 24-ft centrifuge: AQP1 expression was reduced by 47% and 85% in rats adapted for 14 days to 2 G and 3 G, respectively. AQP1 is downregulated in the apical membrane of choroidal cells in response to altered gravity and is rapidly restored after readaptation to normal gravity. This suggests that water transport, which is partly involved in the choroidal production of cerebrospinal fluid, might be decreased during spaceflight and after chronic hypergravity. (+info)Microgravity and hypergravity effects on fertilization of the salamander Pleurodeles waltl (urodele amphibian). (5/95)
Effects of microgravity (microG) on fertilization were studied in the urodele amphibian Pleurodeles waltl on board the MIR space station. Genetic and cytomorphologic analyses ruled out parthenogenesis or gynogenesis and proved that fertilization did occur in microG. Actual fertilization was demonstrated by the analysis of the distribution of peptidase-1 genes, a polymorphic sex-linked enzyme, in progenies obtained in microG. Further evidence of fertilization was provided by the presence of spermatozoa in the perivitelline space and in the fertilization layer of the microG eggs and by the presence of a female pronucleus and male pronuclei in the egg cytoplasm. Experiments in microG and in 1.4G, 2G, and 3G hypergravity showed for the first time that, compared to eggs in 1G, several characteristics of the fertilization process including the cortical reaction and the microvillus transformations were altered depending on the gravitational force applied to the eggs. Microvillus elevation, the most evident feature, was reduced on microG-eggs and amplified on eggs submitted to 2G and 3G. No lethal consequences of these alterations on the early development of microG-eggs were observed. (+info)Selected contribution: redistribution of pulmonary perfusion during weightlessness and increased gravity. (6/95)
To compare the relative contributions of gravity and vascular structure to the distribution of pulmonary blood flow, we flew with pigs on the National Aeronautics and Space Administration KC-135 aircraft. A series of parabolas created alternating weightlessness and 1.8-G conditions. Fluorescent microspheres of varying colors were injected into the pulmonary circulation to mark regional blood flow during different postural and gravitational conditions. The lungs were subsequently removed, air dried, and sectioned into approximately 2 cm(3) pieces. Flow to each piece was determined for the different conditions. Perfusion heterogeneity did not change significantly during weightlessness compared with normal and increased gravitational forces. Regional blood flow to each lung piece changed little despite alterations in posture and gravitational forces. With the use of multiple stepwise linear regression, the contributions of gravity and vascular structure to regional perfusion were separated. We conclude that both gravity and the geometry of the pulmonary vascular tree influence regional pulmonary blood flow. However, the structure of the vascular tree is the primary determinant of regional perfusion in these animals. (+info)Effects of 2-G exposure on temperature regulation, circadian rhythms, and adiposity in UCP2/3 transgenic mice. (7/95)
Altered ambient force environments affect energy expenditure via changes in thermoregulation, metabolism, and body composition. Uncoupling proteins (UCPs) have been implicated as potential enhancers of energy expenditure and may participate in some of the adaptations to a hyperdynamic environment. To test this hypothesis, this study examined the homeostatic and circadian profiles of body temperature (T(b)) and activity and adiposity in wild-type and UCP2/3 transgenic mice exposed to 1 and 2 G. There were no significant differences between the groups in the means, amplitudes, or phases of T(b) and activity rhythms at either the 1- or 2-G level. Percent body fat was significantly lower in transgenic (5.2 +/- 0. 2%) relative to the wild-type mice (6.2 +/- 0.1%) after 2-G exposure; mass-adjusted mesenteric and epididymal fat pads in transgenic mice were also significantly lower (P < 0.05). The data suggest that 1) the actions of two UCPs (UCP2 and UCP3) do not contribute to an altered energy balance at 2 G, although 2) UCP2 and UCP3 do contribute to the utilization of lipids as a fuel substrate at 2 G. (+info)Restoration of gravitropic sensitivity in starch-deficient mutants of Arabidopsis by hypergravity. (8/95)
Despite the extensive study of plant gravitropism, there have been few experiments which have utilized hypergravity as a tool to investigate gravisensitivity in flowering plants. Previous studies have shown that starch-deficient mutants of Arabidopsis are less sensitive to gravity compared to the wild-type (WT). In this report, the question addressed was whether hypergravity could restore the sensitivity of starch-deficient mutants of Arabidopsis. The strains examined include a WT, a starchless mutant and a reduced-starch mutant. Vertical orientation studies with dark-grown seedlings indicate that increased centrifugal acceleration improves orientation relative to the acceleration vector for all strains, even the WT. For starchless roots, growth of seedlings under constant 5 g acceleration was required to restore orientation to the level of the WT at 1 g. In contrast, approximately 10 g was required to restore the orientation of the starchless mutant hypocotyls to a WT level at 1 g. Examination of plastid position in root cap columella cells of the starchless mutant revealed that the restoration of gravitropic sensitivity was correlated with the sedimentation of plastids toward the distal cell wall. Even in WT plants, hypergravity caused greater sedimentation of plastids and improved gravitropic capability. Collectively, these experiments support the hypothesis of a statolith-based system of gravity perception in plants. As far as is known, this is the first report to use hypergravity to study the mechanisms of gravitropism in Arabidopsis. (+info)Hypergravity is a term used to describe an environment where the force of gravity is greater than that which we normally experience on Earth's surface (1G). This can occur in various situations such as high-speed aircraft rides, space travel, or in certain laboratory settings. It leads to increased gravitational load and force on the body, which can have various physiological effects, including cardiovascular changes, muscle tension, and altered body positioning. Prolonged exposure to hypergravity can lead to physical fatigue and discomfort.
Weightlessness, also known as zero gravity or microgravity, is a condition in which people or objects appear to be weightless. The effects of weightlessness on the human body are similar to those experienced during freefall.
This state can be achieved in various ways:
1. Freefall: This is the natural weightless state that occurs when an object is in free fall and accelerating towards the center of a celestial body such as Earth, but is not being affected by any other forces (like air resistance). During this state, the only force acting upon the object is gravity, which pulls everything towards the center of the planet. This is why astronauts experience weightlessness during space travel.
2. Neutral Buoyancy: In a fluid medium like water, an object can achieve neutral buoyancy when its weight equals the weight of the fluid it displaces. This creates a state where the object neither sinks nor floats, appearing to be weightless.
3. Specialized Equipment: Devices such as aircraft that fly in parabolic arcs can create short periods of weightlessness for training purposes or research. These flights involve climbing steeply, then diving towards the earth, creating a state of freefall and thus weightlessness.
Prolonged exposure to weightlessness can have significant effects on the human body, including muscle atrophy, bone loss, balance disorders, and changes in cardiovascular function.
I'm sorry for any confusion, but "gravitation" is not a term that is typically used in the context of medical definitions. Gravitation is a fundamental force that attracts two objects with mass towards each other. It is the force that causes objects to fall towards the earth and keeps the planets in orbit around the sun.
In the field of medicine, the concepts of gravity or gravitational forces are not directly relevant to the diagnosis or treatment of medical conditions. However, there may be some indirect applications related to physiology and human health, such as the effects of microgravity on the human body during space travel.
I'm sorry for any confusion, but "hypogravity" is not a term used in medical definitions. The term "hypogravity" is related to physics and astronomy, and it refers to a state of being subjected to a gravitational force that is significantly lower than that of Earth. It's not a concept that's directly applicable to medical science. If you have any questions related to medical definitions or health concerns, I would be happy to help answer those!
Weightlessness simulation, also known as "zero-gravity" or "microgravity" simulation, is the reproduction of the condition in which people or objects appear to be weightless. This state can be achieved through various methods, including neutral buoyancy, which is simulating the feeling of weightlessness by immersing individuals in a fluid (usually water) with a density equal to their body, or reduced-gravity environments created using specialized equipment such as aircraft that fly in parabolic arcs to generate brief periods of weightlessness.
Another method for weightlessness simulation is through the use of virtual reality and other technology to create an illusion of weightlessness. This can be done by manipulating visual and auditory cues, as well as providing a haptic feedback system that simulates the sensation of movement in zero-gravity environments. These simulations are often used for training astronauts, researching the effects of weightlessness on the human body, and developing technologies for use in space.
Centrifugation is a laboratory technique that involves the use of a machine called a centrifuge to separate mixtures based on their differing densities or sizes. The mixture is placed in a rotor and spun at high speeds, causing the denser components to move away from the center of rotation and the less dense components to remain nearer the center. This separation allows for the recovery and analysis of specific particles, such as cells, viruses, or subcellular organelles, from complex mixtures.
The force exerted on the mixture during centrifugation is described in terms of relative centrifugal force (RCF) or g-force, which represents the number of times greater the acceleration due to centrifugation is than the acceleration due to gravity. The RCF is determined by the speed of rotation (revolutions per minute, or RPM), the radius of rotation, and the duration of centrifugation.
Centrifugation has numerous applications in various fields, including clinical laboratories, biochemistry, molecular biology, and virology. It is a fundamental technique for isolating and concentrating particles from solutions, enabling further analysis and characterization.
"Space flight" is not a term that has a specific medical definition. However, in general, it refers to the act of traveling through space, outside of Earth's atmosphere, aboard a spacecraft. This can include trips to the International Space Station (ISS), lunar missions, or travel to other planets and moons within our solar system.
From a medical perspective, space flight presents unique challenges to the human body, including exposure to microgravity, radiation, and isolation from Earth's biosphere. These factors can have significant impacts on various physiological systems, including the cardiovascular, musculoskeletal, sensory, and immune systems. As a result, space medicine has emerged as a distinct field of study focused on understanding and mitigating these risks to ensure the health and safety of astronauts during space flight.
I'm sorry for any confusion, but "flowering tops" is not a standard medical term. The term "flowering tops" is commonly used in the context of cannabis cultivation and refers to the top colas or buds of female cannabis plants that are covered in trichomes and are therefore the most potent part of the plant. If you have any questions about medical terminology, I would be happy to help clarify those for you!
"Altered gravity" is not a medical condition or diagnosis itself, but rather a state that can have various medical implications. It refers to a situation where the force of gravity is different from what humans normally experience on Earth's surface (approximately 9.8 m/s²). This could include conditions such as:
1. Microgravity: This is the condition experienced in outer space, where the force of gravity is significantly reduced. It can have various effects on the human body, including muscle atrophy, bone loss, fluid shifts, and changes in balance and coordination.
2. Hypergravity: This refers to environments where the force of gravity is greater than Earth's normal level. Examples might include high-speed centrifuges or certain types of space travel. Hypergravity can lead to symptoms such as nausea, disorientation, and cardiovascular changes.
Medical research into altered gravity conditions is important for understanding the effects of space travel on the human body, as well as for developing countermeasures to mitigate these effects.
Weightlessness countermeasures refer to the methods and techniques used to prevent or minimize the negative effects of weightlessness (or microgravity) on the human body during spaceflight. Prolonged exposure to weightlessness can lead to various physiological changes, such as muscle atrophy, bone loss, cardiovascular deconditioning, and balance disorders. Weightlessness countermeasures aim to mitigate these effects through various strategies, including:
1. Exercise: Regular exercise, particularly resistance and aerobic exercises, helps maintain muscle strength, endurance, and cardiovascular fitness during spaceflight. Devices like the Advanced Resistive Exercise Device (ARED) and treadmills are used on the International Space Station (ISS) to provide a suitable exercise routine for astronauts.
2. Nutrition: Adequate nutrient intake, including calcium, vitamin D, and protein, is essential for maintaining bone and muscle health during spaceflight. Monitoring and optimizing dietary habits can help counteract the negative effects of weightlessness on the body.
3. Medications and supplements: Some medications and supplements may be used to prevent or treat specific issues related to weightlessness, such as bone loss (bisphosphonates) or muscle wasting (anabolic agents). However, these interventions should be carefully evaluated for their risks and benefits.
4. Artificial gravity: Systems that create a gravitational force, such as rotating spacecraft or centrifuges, can help maintain the body's physiological adaptations to Earth's gravity. Although not yet implemented in human spaceflight, artificial gravity is a promising countermeasure for long-duration missions.
5. Pre- and post-flight rehabilitation: A well-structured rehabilitation program before and after spaceflight can help astronauts recover more quickly from the effects of weightlessness and reduce the risk of long-term health issues.
6. Monitoring and telemedicine: Regular monitoring of physiological parameters, such as muscle mass, bone density, and cardiovascular function, allows for early detection and intervention of any adverse effects related to weightlessness. Telemedicine can also provide remote medical support and guidance during space missions.
Overall, a comprehensive approach that combines various countermeasures is essential for minimizing the negative impacts of weightlessness on astronaut health during and after space missions.
"Gravity suits" is not a recognized medical term. However, in the context of space medicine and space travel, gravity suits, also known as g-suits or anti-G suits, are specialized garments worn by pilots and astronauts to prevent or reduce the negative effects of high gravitational forces (G-forces) on their bodies during high-speed maneuvers or while re-entering the Earth's atmosphere.
These suits work by applying pressure to specific areas of the body, typically around the lower abdomen and legs, to prevent the pooling of blood in those areas due to the increased G-forces. This helps maintain adequate blood flow to the brain and other vital organs, reducing the risk of loss of consciousness (G-induced Loss of Consciousness or G-LOC) and other symptoms associated with high G-forces such as blackouts, vision impairment, and disorientation.
It's important to note that gravity suits are not used as a medical treatment for any specific condition but rather as a protective measure during space travel and high-performance aviation.
Arsanilic acid is a type of arsenical compound that was once used in medicine, particularly as a veterinary medication, for the treatment and prevention of certain parasitic diseases. It is an organic compound containing arsenic, with the chemical formula As(C6H5O3)2.
Arsanilic acid has been largely replaced by other medications due to its potential toxicity and the availability of safer alternatives. Prolonged exposure or ingestion of high doses of arsanilic acid can lead to arsenic poisoning, which may cause symptoms such as nausea, vomiting, abdominal pain, diarrhea, and in severe cases, neurological damage, liver and kidney failure, and even death.
It is important to note that the use of arsanilic acid in human medicine is now highly restricted and its handling should be done with caution due to its potential health hazards.
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