SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Ultraviolet microscopy is used by cytologists and biochemists to study the morphological and physiological changes in the living cell under varied culture conditions. The yeast cell is used because of its content of ultraviolet absorbing materials and its lack of motility.
The effects of spaceflight on erythropoiesis and blood volume in the rat were studied during the 14-day NASA Spacelab Life Sciences 2 (SLS-2) Shuttle mission. Measurements included red blood cell mass (RBCM), plasma volume (PV), iron utilization and iron utilization in response to an injection of erythropoietin. Red blood cell (RBC) survival, splenic sequestration and erythrocyte morphology were also evaluated. At landing, the RBCM adjusted for body weight was significantly lower in the flight animals than in the ground controls. While the PV was also decreased, the change was not statistically significant. Incorporation of iron into circulating RBCs was normal when measured after five days of spaceflight and the rat responded normally to the single in-flight injection of erythropoietin. No change in RBC morphology could be attributed to spaceflight. A normal survival was found for the RBC population that was represented by Cr-51 labeled RBCS. These results demonstrate that rats, like humans, return from spaceflight with a decreased RBCM and total blood volume.
Loss of functional weight bearing, such as experienced during space flight or bed rest (BR), distorts intervertebral disc (IVD) and muscle morphology. IVDs are avascular structures consisting of cells that may derive their nutrition and waste removal from the load induced fluid flow into and out of the disc. A diurnal cycle is produced by forces related to weight bearing and muscular activity, and comprised of a supine and erect posture over a 24 hr period. A diurnal cycle will include a disc volume change of approx. 10-13%. However, in space there are little or no diurnal changes because of the microgravity, which removes the gravitational load and compressive forces to the back muscles. The BR model and the etiology of the disc swelling and muscle atrophy could provide insight into those subjects confined to bed for chronic disease/injury and aging. We hypothesize that extremely low-magnitude, high frequency mechanical vibrations will abate the disc degeneration and muscle loss associated with long-term BR.
The objective of the research was to begin evaluating the effect of zero-shear on the development of the cell wall of Saccharomyces cerevisiae employing the High Aspect Rotating-Wall Vessel (HARV) NASA bioreactor. This particular yeast has enormous potential for research as a model eukaryotic system on the International Space Station, as well as the production of food stuffs' at the future lunar colony. Because the cell wall is the barrier between the cell and the environment, its form and function as influenced by microgravity is of great importance. Morphologic studies revealed that the circularity and total area of the individual yeast cells were essentially the same in both the control and test HARV's. The growth rates were also essentially the same. In zero-shear, the yeast grew in clumps consisting of rudimentary pseudohyphae in contrast to solitary budding cells in the control. Based upon mechanical and sonic shear applied to the yeast cells, those grown in zero-shear had stronger cell walls and septa. This suggests that there are structural differences, most likely related to the chitin skeleton of the cell wall. From this research further NASA support was obtained to continue the work. Investigations will deal with gene expression and ultrastructure. These will lead to a clearer assessment of the value of S. cerevisiae eukaryotic as a model for space station research.
We propose a multifunctional X-ray facility for the Materials, Biotechnology and Life Sciences Programs to visualize formation and behavior dynamics of materials, biomaterials, and living organisms, tissues and cells. The facility will combine X-ray topography, phase micro-imaging and scattering capabilities with sample units installed on the goniometer. This should allow, for the first time, to monitor under well defined conditions, in situ, in real time: creation of imperfections during growth of semiconductors, metal, dielectric and biomacromolecular crystals and films, high-precision diffraction from crystals within a wide range of temperatures and vapor, melt, solution conditions, internal morphology and changes in living organisms, tissues and cells, diffraction on biominerals, nanotubes and particles, radiation damage, also under controlled formation/life conditions. The system will include an ultrabright X-ray source, X-ray mirror, monochromator, image-recording unit, detectors, and multipurpose diffractometer that fully accommodate and integrate furnaces and samples with other experimental environments. The easily adjustable laboratory and flight versions will allow monitoring processes under terrestrial and microgravity conditions. The flight version can be made available using a microsource combined with multilayer or capillary optics.
The experiments described are aimed at exploring PTH regulation of production of collagenase and protein inhibitors of collagenase (tissue inhibitors of metalloproteases, TIMP-1 and -2) by osteoblast-like osteosarcoma cells under conditions of weightlessness. The results of this work will contribute to information as to whether a microgravity environment alters the functions and responsiveness of the osteoblast. The objectives of the Bone Culture Research (BCR) experiment are: to observe the effects of microgravity on the morphology, rate of proliferation, and behavior of the osteoblastic cells, UMR 106-01; to determine whether microgravy affects the hormonal sensitivity of osteroblastic cells; and to measure the secretion of collagenase and its inhibitors into the medium under conditions of microgravity. The methods employed will consist of the following: the osteoblast-like cells, UMR-106-01, will be cultured in four NASDA cell culture chambers; two chambers will be subjected to microgravity on SL-J; two chambers will remain on the ground at KSC as ground controls but subjected to an identical set of culture conditions as on the shuttle; media will be changed four times; twice the cells will receive the hormone parathyroid hormone-related protein (PTHrP) and media collected; cells will be photographed under conditions of microgravity; and media and photographs will be analyzed upon return to determine whether functions of the cells changed.
Magnetite crystals produced by terrestrial magnetotactic bacterium MV-1 are elongated on a [111] crystallographic axis, in a so-called truncated hexa-Octahedral shape. This morphology has been proposed to constitute a biomarker (i.e., formed only in biogenic processes). A subpopulation of magnetite crystals associated with carbonate globules in Martian meteorite ALH84001 is reported to have this morphology, and the observation has been taken as evidence for biological activity on Mars. In this study, we present evidence for the exclusively inorganic origin of [111]-elongated magnetite crystals in ALH84001. We report three-dimensional(3-D) morphologies for approx.1000 magnetite crystals extracted from: (1) thermal decomposition products of Fe-rich carbonate produced by inorganic hydrothermal precipitation in laboratory experiments; (2) carbonate globules in Martian meteoriteeALH84001; and (3) cells of magnetotactic bacterial strain MV-1. The 3-D morphologies were derived by fitting 3-D shape models to two-dimensional bright-field transmission-electron microscope (TEAM) images obtained at a series of viewing angles. The view down the {110} axes closest to the [111] elongation axis of magnetite crystals ([111]x{110) not equal to 0) provides a 2-D projection that uniquely discriminates among the three [111]-elongated magnetite morphologies found in these samples: [111]-elongated truncated hexaoctahedron ([111]-THO), [111]-elongated cubo-octahedron ([111]-ECO), and [111]-elongated simple octahedron ([111]-ESO). All [111] -elongated morphologies are present in the three types of sample, but in different proportions. In the ALH84001 Martian meteorite and in our inorganic laboratory products, the most common [111]-elongated magnetite crystal morphology is [111]-ECO. In contrast, the most common morphology for magnetotactic bacterial strain MV-1 is [111]-THO. These results show that: (1) the morphology of [111]-elongated magnetite crystals associated with the carbonate globules in Martian meteorite ALH84001 is replicated by an inorganic process; and (2) the most common crystal morphology for biogenic (MV-1) magnetite is distinctly different from that in both ALH84001 and our inorganic laboratory products. Therefore, [111]-elongated magnetite crystals in ALH84001 do not constitute, as previously claimed, a robust biosignature and, in fact, an exclusively inorganic origin for the magnetite is fully consistent with our results. Furthermore, the inorganic synthesis method, i.e., the thermal decomposition of hydrothermally precipitated Fe-rich carbonate, is a process analogue for formation of the magnetite on Mars. Namely, precipitation of carbonate globules from carbonate-rich hydrothermal solutions followed at some later time by a thermal pulse, perhaps in association with meteoritic impact or volcanic processes on the Martian surface.
What is the threshold gravity (minimum gravity level) required for the nominal functioning of the human system? What dosage is required? Do human cell lines behave differently in microgravity in response to an external stimulus? The critical need for such a gravity simulator is emphasized by recent experiments on human epithelial cells and lymphocytes on the Space Shuttle clearly showing that cell growth and function are markedly different from those observed terrestrially. Those differences are also dramatic between cells grown in space and those in Rotating Wall Vessels (RWV), or NASA bioreactor often used to simulate microgravity, indicating that although morphological growth patterns (three dimensional growth) can be successiblly simulated using RWVs, cell function performance is not reproduced - a critical difference. If cell function is dramatically affected by gravity off-loading, then cell response to stimuli such as radiation, stress, etc. can be very different from terrestrial cell lines. Yet, we have no good gravity simulator for use in study of these phenomena. This represents a profound shortcoming for countermeasures research. We postulate that we can use magnetic levitation of cells and tissue, through the use of strong magnetic fields and field gradients, as a terrestrial microgravity model to study human cells. Specific objectives of the research are: 1. To develop a tried, tested and benchmarked terrestrial microgravity model for cell culture studies; 2. Gravity threshold determination; 3. Dosage (magnitude and duration) of g-level required for nominal functioning of cells; 4. Comparisons of magnetic levitation model to other models such as RWV, hind limb suspension, etc. and 5. Cellular response to reduced gravity levels of Moon and Mars.
What is the threshold gravity (minimum gravity level) required for the nominal functioning of the human system? What dosage is required? Do human cell lines behave differently in microgravity in response to an external stimulus? The critical need for such a gravity simulator is emphasized by recent experiments on human epithelial cells and lymphocytes on the Space Shuttle clearly showing that cell growth and function are markedly different from those observed terrestrially. Those differences are also dramatic between cells grown in space and those in Rotating Wall Vessels (RWV), or NASA bioreactor often used to simulate microgravity, indicating that although morphological growth patterns (three dimensional growth) can be successfully simulated using RWVs, cell function performance is not reproduced - a critical difference. If cell function is dramatically affected by gravity off-loading, then cell response to stimuli such as radiation, stress, etc. can be very different from terrestrial cell lines. Yet, we have no good gravity simulator for use in study of these phenomena. This represents a profound shortcoming for countermeasures research. We postulate that we can use magnetic levitation of cells and tissue, through the use of strong magnetic fields and field gradients, as a terrestrial microgravity model to study human cells. Specific objectives of the research are: 1. To develop a tried, tested and benchmarked terrestrial microgravity model for cell culture studies; 2. Gravity threshold determination; 3. Dosage (magnitude and duration) of g-level required for nominal functioning of cells; 4. Comparisons of magnetic levitation model to other models such as RWV, hind limb suspension, etc. and 5. Cellular response to reduced gravity levels of Moon and Mars. The paper will discuss experiments md modeling work to date in support of this project.
What is the threshold gravity (minimum gravity level) required for the nominal functioning of the human system? What dosage is required (magnitude and duration)? Do human cell lines behave differently in microgravity in response to an external stimulus? The critical need for a variable gravity simulator is emphasized by recent experiments on human epithelial cells and lymphocytes on the Space Shuttle clearly showing that cell growth and function are markedly different from those observed terrestrially. Those differences are also dramatic between cells grown in space and those in Rotating Wall Vessels (RWV), or NASA bioreactor often used to simulate microgravity, indicating that although morphological growth patterns (three dimensional growth) can be successfully simulated using RWVs, cell function performance is not reproduced - a critical difference. If cell function is dramatically affected by gravity off-loading, then cell response to stimuli such as radiation, stress, etc. can be very different from terrestrial cell lines. Yet, we have no good gravity simulator for use in study of these phenomena. This represents a profound shortcoming for countermeasures research. We postulate that we can use magnetic levitation of cells and tissue, through the use of strong magnetic fields and field gradients, as a terrestrial microgravity model to study human cells. Specific objectives of the research are: 1. To develop a tried, tested and benchmarked terrestrial microgravity model for cell culture studies; 2. Gravity threshold determination; 3. Dosage (magnitude and duration) of g-level required for nominal functioning of cells; 4. Comparisons of magnetic levitation model to other models such as RWV, hind limb suspension, etc. and 5. Cellular response to reduced gravity levels of Moon and Mars.
A heterotrophic mastigote from the flat laminated Microcoleus-dominated intertidal microbial mat at the Sippewissett salt marsh, Cape Cod, Massachusetts, was isolated into monoprotist culture in the same anoxic medium that led to spirochete and other anaerobic bacterial enrichments. The protist grew vigorously and was transferred indefinitely in oxic marine medium. Videomicroscopy as well as scanning and transmission electron microscopy were used to document its features. The swimming and perching behavior, nutritional mode (bactivory) and morphology including ultra-structure identify it as an aloricate bicosoecid. The presence of heteromorphic acronematic undulipodia, bilateral bipartite tubular mastigonemes, absence of a cytostome, absence of extrusomes, and presence of "Dauerstadien" (duration stages) distinguish this from other Cafeteriaceae bicosoecids. Cell division involves a closed intranuclear spindle. The unspecialized bicosoecid morphology and behavior juxtaposed with oomycete-like vesicles and mastigonemes suggest that this protist may be an extant descendant of a common ancestor of bicosoecids and other stramenopiles (e.g. labyrinthulids, thraustochytrids and oomycetes). A new genus and species, Acronema sippewissettensis, are proposed.
Chromatin is thought to be structurally discontinuous because it is packaged into morphologically distinct chromosomes that appear physically isolated from one another in metaphase preparations used for cytogenetic studies. However, analysis of chromosome positioning and movement suggest that different chromosomes often behave as if they were physically connected in interphase as well as mitosis. To address this paradox directly, we used a microsurgical technique to physically remove nucleoplasm or chromosomes from living cells under isotonic conditions. Using this approach, we found that pulling a single nucleolus or chromosome out from interphase or mitotic cells resulted in sequential removal of the remaining nucleoli and chromosomes, interconnected by a continuous elastic thread. Enzymatic treatments of interphase nucleoplasm and chromosome chains held under tension revealed that mechanical continuity within the chromatin was mediated by elements sensitive to DNase or micrococcal nuclease, but not RNases, formamide at high temperature, or proteases. In contrast, mechanical coupling between mitotic chromosomes and the surrounding cytoplasm appeared to be mediated by gelsolin-sensitive microfilaments. Furthermore, when ion concentrations were raised and lowered, both the chromosomes and the interconnecting strands underwent multiple rounds of decondensation and recondensation. As a result of these dynamic structural alterations, the mitotic chains also became sensitive to disruption by restriction enzymes. Ion-induced chromosome decondensation could be blocked by treatment with DNA binding dyes, agents that reduce protein disulfide linkages within nuclear matrix, or an antibody directed against histones. Fully decondensed chromatin strands also could be induced to recondense into chromosomes with pre-existing size, shape, number, and position by adding anti-histone antibodies. Conversely, removal of histones by proteolysis or heparin treatment produced chromosome decondensation which could be reversed by addition of histone H1, but not histones H2b or H3. These data suggest that DNA, its associated protein scaffolds, and surrounding cytoskeletal networks function as a structurally-unified system. Mechanical coupling within the nucleoplasm may coordinate dynamic alterations in chromatin structure, guide chromosome movement, and ensure fidelity of mitosis.
BACKGROUND: Rho family GTPase regulation of the actin cytoskeleton governs a variety of cell responses. In this report, we have analyzed the role of the GTPase Rho in maintenance of the T lymphocyte actin cytoskeleton. RESULTS: Inactivation of the GTPase Rho in the human T lymphocytic cell line HPB-ALL does not inhibit constitutively high adhesion to the integrin beta1 substrate fibronectin. It did however result in the aberrant extension of finger-like dendritic processes on the substrates VCAM-1, Fn, and mAb specific to beta1 integrins. Time-lapse video microscopy demonstrated that C3 induced extensions were primarily the result of an altered pseudopod elongation rather than retraction. Once the stellate pseudopodia extended, none retracted, and cells became completely immobile. Filipodial structures were absent and the dendritic-like processes in C3 treated cells were rich in filamentous actin. Immunolocalization of RhoA in untreated HPB-ALL cells spreading on fibronectin demonstrated a diffuse staining pattern within the pseudopodia. In C3 treated cells, clusters of RhoA were pronounced and localized within the altered extensions. CONCLUSIONS: GTPase Rho is actively involved in the regulation of T lymphocyte morphology and motility.
It has long been recognized that flow in the melt can have a profound influence on the dynamics of a solidifying interface and hence the quality of the solid material. In particular, flow affects the heat and mass transfer, and causes spatial and temporal variations in the flow and melt composition. This results in a crystal with nonuniform physical properties. Flow can be generated by buoyancy, expansion or contraction upon phase change, and thermo-soluto capillary effects. In general, these flows can not be avoided and can have an adverse effect on the stability of the crystal structures. This motivates crystal growth experiments in a microgravity environment, where buoyancy-driven convection is significantly suppressed. However, transient accelerations (g-jitter) caused by the acceleration of the spacecraft can affect the melt, while convection generated from the effects other than buoyancy remain important. Rather than bemoan the presence of convection as a source of interfacial instability, Hurle in the 1960s suggested that flow in the melt, either forced or natural convection, might be used to stabilize the interface. Delves considered the imposition of both a parabolic velocity profile and a Blasius boundary layer flow over the interface. He concluded that fast stirring could stabilize the interface to perturbations whose wave vector is in the direction of the fluid velocity. Forth and Wheeler considered the effect of the asymptotic suction boundary layer profile. They showed that the effect of the shear flow was to generate travelling waves parallel to the flow with a speed proportional to the Reynolds number. There have been few quantitative, experimental works reporting on the coupling effect of fluid flow and morphological instabilities. Huang studied plane Couette flow over cells and dendrites. It was found that this flow could greatly enhance the planar stability and even induce the cell-planar transition. A rotating impeller was buried inside the sample cell, driven by an outside rotating magnet, in order to generate the flow. However, it appears that this was not a well-controlled flow and may also have been unsteady. In the present experimental study, we want to study how a forced parallel shear flow in a Hele-Shaw cell interacts with the directionally solidifying crystal interface. The comparison of experimental data show that the parallel shear flow in a Hele-Shaw cell has a strong stabilizing effect on the planar interface by damping the existing initial perturbations. The flow also shows a stabilizing effect on the cellular interface by slightly reducing the exponential growth rate of cells. The left-right symmetry of cells is broken by the flow with cells tilting toward the incoming flow direction. The tilting angle increases with the velocity ratio. The experimental results are explained through the parallel flow effect on lateral solute transport. The phenomenon of cells tilting against the flow is consistent with the numerical result of Dantzig and Chao.
For the last 3 decades evidence has been accumulating that some types of mammalian cells respond to their mechanically active environment by altering their morphology, growth rate, and metabolism. The study of such responses is very important in understanding, physiological and pathological conditions ranging from bone formation to atherosclerosis. Obtaining this knowledge has been the goal for an active research area in bioengineering termed cell mechanotransduction. The advancement of optical methodologies used in cell biology research has given the tools to elucidate cellular mechanisms that would otherwise be impossible to visualize. Combined with molecular biology techniques, they give engineers invaluable tools in understanding the chemical pathways involved in mechanotransduction. Herein we briefly review the current knowledge on mechanical signal transduction in mammalian cells, focusing on the application of novel optical techniques in the ongoing research.
Metal electrodeposition may introduce various morphological variations depending on the electrolytic conditions including cell configurations. For liquid electrolytes, a precise study of these deposits may be complicated by convective motion due to buoyancy. Zero-gravity (0-G) condition provided by drop shaft or parabolic flight gives a straightforward mean to avoid this effect: we present here 0-G electrodeposition experiments, which we compare to ground experiments (1-G). Two electrochemical systems were studied by laser interferometry, allowing to measure the concentration variations in the electrolyte: copper deposition from copper sulfate aqueous solution and lithium deposition from an ionic liquid containing LiTFSI. For copper, concentration variations were in good agreement with theory. For lithium, an apparent induction time was observed for the concentration evolution at 1-G: due to this induction time and to the low diffusion coefficient in ionic liquid, the concentration variations were hardly measurable in the parabolic flight 0-G periods of 20 seconds.
Hair cells in the bullfrog vestibular otolith organs regenerate following aminoglycoside ototoxicity. Hair cells in these organs are differentially sensitive to gentamicin, with saccular hair cells and hair cells in the utricular striola being damaged at lower gentamicin concentrations than hair cells in the utricular extrastriola. Regenerating hair cells in these organs have short hair bundles and can be classified into a number of phenotypes using the same morphological criteria used to identify their mature counterparts. Our studies suggest that some supporting cells can convert, or transdifferentiate,into hair cells without an intervening cell division. By stimulating these processes in humans, clinicians may be able to alleviate human deafness and peripheral vestibular disorders by regenerating and replacing lost hair cells. In vivo and in vitro studies were done on cell proliferation and hair cell regeneration.
BACKGROUND: We have described the rapid destruction of young red blood cells (neocytolysis) in astronauts adapting to microgravity, in polycythemic high altitude dwellers who descend to sea level, and in patients with kidney disorders. This destruction results from a decrease in erythropoietin (EPO) production. We hypothesized that such EPO withdrawal could trigger physiological changes in cells other than red cell precursors and possibly lead to the uptake and destruction of young red cells by altering endothelial cell-macrophage interactions, most likely occurring in the spleen. METHODS: We identified EPO receptors on human splenic endothelial cells (HSEC) and investigated the responses of these cells to EPO withdrawal. RESULTS: A monolayer of HSEC, unlike human endothelial cells from aorta, glomerulus, or umbilical vein, demonstrated an increase in permeability upon EPO withdrawal that was accompanied by unique morphological changes. When HSEC were cultured with monocyte-derived macrophages (but not when either cell type was cultured alone), EPO withdrawal induced an increased ingestion of young red cells by macrophages when compared with the constant presence or absence of EPO. CONCLUSIONS: HSEC may represent a unique cell type that is able to respond to EPO withdrawal by increasing permeability and interacting with phagocytic macrophages, which leads to neocytolysis.