Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “bone”

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.

At least 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Internal tibial torsion correction study

A quantitative study of internal torsion in the entire tibial bone was performed by using strain gauges to measure the amount of deformation occuring at different locations. Comparison of strain measurements with physical dimensions of the bone produced the modulus of rigidity and its behavior under increased torque. Computerized analysis of the stress distribution shows that more strain occurs near the torqued ends of the bones where also most of the twisting and fracturing takes place.

Cantu, J. M.↗
NASA NTRS1973

Skeletal status and soft tissue composition in astronauts. Tissue and fluid changes by radionuclide absorptiometry in vivo

A device has been constructed and tested which provides immediate readout of bone mineral content and bone width from absorptiometric scans with low energy radionuclides. The basis of this analog system is a logarithmic converter-integrator coupled with a precision linear ratemeter. The system provided accurate and reliable results on standards and ashed bone sections. Clinical measurements were made on about 100 patients with the direct readout system, and these were highly correlated with the results from digital scan data on the same patients. The direct readout system has been used successfully in field studies and surveys as well as for clinical observations.

Cameron, J. R.↗
NASA NTRS1975

Effects of a 2X gravity environment on the ultrastructure of the gerbil parathyroid gland

A number of studies concerning the effects of hypergravity on bone have shown increases in bone mass or bone dimensions. Correlative studies, which could provide clues to the mechanism for such a response, have been lacking. The purpose of the present study was to evaluate the ultrastructure of parathyroid glands of Mongolian gerbils exposed to a continuous 2 X gravity force for 60 d. It was found that the experimental animals had parathyroid glands which had a greater percentage of chief cells in the active stage of their secretory cycle when compared with control animals. This result was interpreted to indicate an increase in parathyroid gland secretory activity and, hence, an increase in parathyroid hormone release. It was suggested that increased parathyroid secretory activity was necessary to maintain serum calcium levels of hypergravity animals within normal limits. Cellular forms resembling water clear cells and highly compact, degenerating cells were described in experimental animals but not in controls. Areas suggestive of cellular dissolution and disorganization were also reported in experimental parathyroids.

Sannes, P. L.↗
NASA NTRS1979

Prosthesis coupling

A coupling for use in an apparatus for connecting a prosthesis to the bone of a stump of an amputated limb is described which permits a bio-compatible carbon sleeve forming a part of the prosthesis connector to float so as to prevent disturbing the skin seal around the carbon sleeve. The coupling includes a flexible member interposed between a socket that is inserted within an intermedullary cavity of the bone and the sleeve. A lock pin is carried by the prosthesis and has a stem portion which is adapted to be coaxially disposed and slideably within the tubular female socket for securing the prosthesis to the stump. The skin around the percutaneous carbon sleeve is able to move as a result of the flexing coupling so as to reduce stresses caused by changes in the stump shape and/or movement between the bone and the flesh portion of the stump.

Reswick, J. B.↗
NASA NTRS1980

Effects of factors of prolonged space flight on conditions of tortoise skeleton

After a 60-90 day space flight mild osteoporosis developed in the epiphyses and metaphyses of long tubular bones of tortoises, which was not attributed to reduced mineral saturation of the preserved bone tissue microstructures. The diminished strength of the cancellous bone of the epiphyses in tortoises after space flight was due to the reduced properties of its structure. The strength of the compact substance did not change under the effect of weightlessness.

Stupakon, G. P.↗
NASA NTRS1981

Experiment K307: Vertebral body strength of rat spinal columns

The effects of space flight on vertebral body bone strength excised were investigated. Comparative biomechanical investigations of vertebral body strength for flight, synchronous, and vivarium rats following spacecraft recovery (R+0), at R+6 and R+29 days post flight recovery are presented. Statistical analyses are presented for the mechanical properties of stiffness, ultimate load, displacement to ultimate load, and energy to ultimate load. At R+0 all of the above properties show that the vertebral body exhibits an increasing susceptibility to fracture. The reduction of bone strength is inhomogeneous and dependent on vertebral level. The R+6 recovery data was inconclusive since it varied above and below the R+0 data. At R+29 ultimate load values showed a statistically significant increase in bone strength approaching that of the vivarium or control group.

Kazarian, L. E.↗
NASA NTRS1984

Osseous adaptation to continuous loading of rigid endosseous implants

The effect of loading on etched Ti implants in the femurs of young (3 mo) and adult (6 mo) rabbits is investigated experimentally. The results are presented in photographs, fluorescence and polarization micrographs, radiographs, and drawings and discussed. Implantation is followed by formation of coarse woven bone within 3 d and mature lamellar bone by 6 wks, with nonspecific subperiosteal bony hypertrophy in the young rabbits only. Spring loading at 100 g produces spontaneous spiral-type fractures when applied immediately, but the implants remain rigid when loads are applied after 6-12 wks of healing. The mechanisms of bone formation involved are examined, and the potential of endosseous implants as anchors in orthodontics or dentofacial-orthopedics is confirmed.

Roberts, W. E.↗
NASA NTRS1986

Immobilization-associated osteoporosis in primates

Osteopenic changes in the tibial compact bone of fifteen adult male monkeys immobilized for up to 7 months are examined histologically. Osteonal formation in the proximal tibia is analyzed. The analysis reveals the loss of haversian bone in the proximal tibia, increased activation with excessive depth of penetration of osteoclastic activity, rapid bone loss, and resorption cavities of irregular size and orientation. Osteonal formation following reambulation is examined; the recovery of cortical is a repair and rejuvenation process characterized by refilling of resorption cavities and remodeling activities.

Young, D. R.↗
NASA NTRS1987

Femur-bending properties as influenced by gravity. V - Strength vs. calcium and gravity in rats exposed for 2 weeks

The dependence of gravitationally related changes in femur bone strength on the comparable changes in calcium content was investigated in rats exposed to chronic simulations of altered gravity from the 28th to 42nd day of age. Zero G was simulated by harness suspension and 3 G by centrifugation. Bone strength (S) was determined by bending (using modified quasi-static cantilever bending methods and equipment described by Wunder et al., 1977 and 1979) and Ca content (C, by mass pct) determined by atomic absorption spectrometry; results were compared with data obtained on both normal and harnessed control animals at 1 G. Multiple regression showed significant dependence of S upon earth's gravity, independent from C, for which there was no significant coefficient of partial regression. It is suggested that the lack of S/C correlation might have been due to the fact that considerable fraction of the calcium in these young, developing bones has not yet crystallized into the hydroxyapatite which provides strength.

Wunder, Charles C.↗
NASA NTRS1990

Experiment K-6-02. Biomedical, biochemical and morphological alterations of muscle and dense, fibrous connective tissues during 14 days of spaceflight

Findings on the connective tissue response to short-term space flight (12 days) are discussed. Specifically, data regarding the biochemical, biomechanical and morphological characteristics of selected connective tissues (humerus, vertebral body, tendon and skeletal muscle) of growing rats is given. Results are given concerning the humerus cortical bone, the vertebral bone, nutritional effects on bone biomechanical properties, and soft tense fiber connective tissue response.

Vailas, A.↗
NASA NTRS1989

Work, exercise, and space flight. 2: Modification of adaptation by exercise (exercise prescription)

The fundamentals of exercise theory on earth must be rigorously understood and applied to prevent adaptation to long periods of weightlessness. Locomotor activity, not weight, determines the capacity or condition of the largest muscles and bones in the body and usually also determines cardio-respiratory capacity. Absence of this activity results in rapid atrophy of muscle, bone, and cardio-respiratory capacity. Upper body muscle and bone are less affected depending upon the individual's usual, or 1-g, activities. Methodology is available to prevent these changes but space operations demand that it be done in the most efficient fashion, i.e., shortest time. At this point in time we can reasonably select the type of exercise and methods of obtaining it, but additional work in 1-g will be required to optimize the time.

Thornton, William↗
NASA NTRS1991

Cosmos: 1989 immunology studies

The effects of flight on Cosmos mission 2044 on leukocyte subset distribution and the sensitivity of bone marrow cells to colony stimulating factor-GM were determined. A parallel study with antiorthostatic suspension was also carried out. The study involved repetition and expansion of studies performed on Cosmos 1887. Spleen and bone marrow cells were obtained from flown, vivarium control, synchronous control, and suspended rats. The cells were stained with a series of monoclonal antibodies directed against rat leukocyte cell surface antigens. Control cells were stained with a monoclonal antibody directed against an irrelevant species or were unstained. Cells were then analyzed for fluorescence using a FACSCAN flow cytometer. Bone marrow cells were placed in culture with GM-CSF in McCoy's 5a medium and incubated for 5 days. Cultures were then evaluated for the number of colonies of 50 cells or greater.

Sonnenfeld, Gerald↗
NASA NTRS1992

Spaceflight alters immune cell function and distribution

Experiments are described which were performed onboard Cosmos 2044 to determine spaceflight effects on immunologically important cell function and distribution. Results indicate that bone marrow cells from flown and suspended rats exhibited a decreased response to a granulocyte/monocyte colony-stimulating factor compared with the bone marrow cells from control rats. Bone marrow cells showed an increase in the percentage of cells expressing markers for helper T-cells in the myelogenous population and increased percentages of anti-asialo granulocyte/monocyte-1-bearing interleulin-2 receptor bearing pan T- and helper T-cells in the lymphocytic population.

Sonnenfeld, Gerald↗
NASA NTRS1993

NASA project 1: Full-body dynamometer

In space, where the body does only a fraction of work it does on earth, muscle atrophy is a major concern. The bones and the muscles will begin to deteriorate after a short stay in weightlessness. Bone decalcification appears to be a major problem with extensive living in microgravity. Resistance exercise is not only essential to prevent muscle atrophy in space, it also helps to keep bone decalcification in check. For a space station, where the astronauts are expected to live for months at a time, exercise is especially important. Experts recommend about an hour and a half to two hours of exercise per day to keep the muscles in good condition in microgravity. The exercises will not only keep the astronauts in excellent physical condition, it will also make it easier for them to readjust to earth's gravity on return. The stationary bicycle and the treadmill have been the astronauts' primary sources of exercise since the 1970's. The major problem with both the stationary bicycle and the treadmill is that while they may keep the leg muscles from deteriorating in microgravity, they do little for muscles in the upper body. The National Aeronautics and Space Administration (NASA) is currently developing a full-body dynamometer (FBD), which will provide the astronauts with a full-body workout. It will also test the astronauts for muscle atrophy and rehabilitate the weakened muscle. The specification and the function structure for the FBD is presented.

Lu, Li-Dai↗
NASA NTRS1993

Loading, electromyograph, and motion during exercise

A bicycle ergometer system has been developed to determine forces acting in specific muscles and muscle groups for both cycling and isometric exercise. The bicycle has been instrumented with encoders, accelerometers, and load cells. A harnessing system has been developed to keep subjects in place during isometric exercise. EMG data will also be collected with electrodes attached to various muscles on the subject's leg. Data has been collected for static loading and will be collected for cycling in both an earth-based laboratory and on the KC-135. Once the data is analyzed, the forces will be entered into finite element models of bones of the lower extremities. A finite element model of the tibia-fibula has been generated from the experimental subject's MRI data. The linear elastic isoparametric brick elements representing the bones are connected by linear elastic isoparametric shell elements placed at the locations of ligaments. Models will be generated for the calcaneus and the femur. Material properties for the various tissues will be taken from the literature. The experimentally determined muscle forces will be applied to the models to determine the stress distribution which is created in the bones.

Todd, Beth A.↗
NASA NTRS1993

Cosmos 2229 immunology study (Experiment K-8-07)

The purpose of the current study was to further validate use of the rhesus monkey as a model for humans in future space flight testing. The areas of immunological importance examined in the Cosmos 2229 flight were represented by two sets of studies. The first set of studies determined the effect of space flight on the ability of bone marrow cells to respond to granulocyte/monocyte colony stimulating factor (GM-CSF). GM-CSF is an important regulator in the differentiation of bone marrow cells of both monocyte/macrophage and granulocyte lineages and any change in the ability of these cells to respond to GM-CSF can result in altered immune function. A second set of studies determined space flight effects on the expression of cell surface markers on both spleen and bone marrow cells. Immune cell markers included in this study were those for T-cell, B-cell, natural killer cell, and interleukin-2 populations. Variations from a normal cell population percentage, as represented by these markers, can be correlated with alterations in immunological function. Cells were stained with fluorescein-labelled antibodies directed against the appropriate antigens, and then analyzed using a flow cytometer.

Sonnenfeld, Gerald↗
NASA NTRS1993

A method for continuous monitoring of the Ground Reaction Force during daily activity

Theoretical models and experimental studies of bone remodeling have identified peak cyclic force levels (or cyclic tissue strain energy density), number of daily loading cycles, and load (strain) rate as possible contributors to bone modeling and remodeling stimulus. To test our theoretical model and further investigate the influence of mechanical forces on bone density, we have focused on the calcaneus as a model site loaded by calcaneal surface tractions which are predominantly determined by the magnitude of the external ground reaction force (GRF).

Whalen, Robert↗
NASA NTRS1997

Effects of Hypogravity on Osteoblast Differentiation

Weightbearing is essential for normal skeletal function. Without weightbearing, the rate of bone formation by osteoblasts decreases in the growing rat. Defective formation may account for the decrease in the maturation, strength and mass of bone that is caused by spaceflight. These skeletal defects may be mediated by a combination of physiologic changes triggered by spaceflight, including skeletal unloading, fluid shifts, and stress-induced endocrine factors. The fundamental question of whether the defects in osteoblast function due to weightlessness are mediated by localized skeletal unloading or by systemic physiologic adaptations such as fluid shifts has not been answered. Furthermore, bone-forming activity of osteoblasts during unloading may be affected by paracrine signals from vascular, monocytic, and neural cells that also reside in skeletal tissue. Therefore we proposed to examine whether exposure of cultured rat osteoblasts to spaceflight inhibits cellular differentiation and impairs mineralization when isolated from the influence of both systemic factors and other skeletal cells.

Globus, Ruth↗