Search NASA⌕ Search

SEARCH · Search NASA

Results for “Immobilization”

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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Recovery time course in contractile function of fast and slow skeletal muscle after hindlimb immobilization

The present study was undertaken to characterize the time course and extent of recovery in the isometric and isotonic contractile properties of fast and slow skeletal muscle following 6 wk of hindlimb immobilization. Female Sprague-Dawley rats were randomly assigned to an immobilized group or a control group. The results of the study show that fast and slow skeletal muscles possess the ability to completely recover normal contractile function following 6 wk of hindlimb immobilization. The rate of recovery is dependent on the fiber type composition of the affected muscle.

Witzmann, F. A.↗
NASA NTRS1982

Effect of limb immobilization on skeletal muscle

Current knowledge and questions remaining concerning the effects of limb immobilization on skeletal muscle is reviewed. The most dramatic of these effects is muscle atrophy, which has been noted in cases of muscles fixed at or below their resting length. Immobilization is also accompanied by a substantial decrease in motoneuronal discharges, which results in the conversion of slow-twitch muscle to muscle with fast-twitch characteristics. Sarcolemma effects include no change or a decrease in resting membrane potential, the appearance of extrajunctional acetylcholine receptors, and no change in acetylcholinesterase activity. Evidence of changes in motoneuron after hyperpolarization characteristics suggests that the muscle inactivity is responsible for neuronal changes, rather than vice versa. The rate of protein loss from atrophying muscles is determined solely by the first-order rate constant for degradation. Various other biochemical and functional changes have been noted, including decreased insulin responsiveness and protein synthesis. The model of limb immobilization may also be useful for related studies of muscle adaptation.

Booth, F. W.↗
NASA NTRS1982

Hindlimb immobilization - Length-tension and contractile properties of skeletal muscle

Casts were placed around rat feet in plantar flexion position to immobilize the soleus muscle in a shortened position, while the other foot was fixed in dorsal flexion to set the extensor digitorum longus in a shortened position. The total muscular atrophy and contractile properties were measured at 1, 2, 4, 7, 14, 21, 28, 35, and 42 days after immobilization, with casts being replaced every two weeks. The slow twitch soleus and the fast-twitch vastus lateralis and longus muscles were excised after termination of the experiment. The muscles were then stretched and subjected to electric shock to elicit peak tetanic tension and peak tetanic tension development. Force velocity features of the three muscles were assayed in a series of afterloaded contractions and fiber lengths were measured from subsequently macerated muscle. All muscles atrophied during immobilization, reaching a new steady state by day 21. Decreases in fiber and sarcomere lengths were also observed.

Witzmann, F. A.↗
NASA NTRS1983

Inhibition of cortical and trabecular bone formation in the long bones of immobilized monkeys

Tetracycline derivatives are administered on three separate occasions to label the sites of bone formation. Determinations are made of the tetracycline-labeling frequency and mineral apposition rate of osteons and trabecular bone surfaces in the humerus and femur. The inhibition of bone formation induced by immobilization is found to be more pronounced in trabecular bone. The immobilized monkeys exhibit a moderate, but statistically nonsignificant, reduction in the percentage of osteons forming bone. Conversely, the dramatic decline in the percentage of trabecular surfaces undergoing bone formation in the monkeys is found to be highly significant. The diminished rate of mineral apposition in osteons is seen as suggesting that osteoblastic activity is impaired in cortical bone during immobilization.

Wronski, T. J.↗
NASA NTRS1988

Effects of immobilization on rat hind limb muscles under non-weight-bearing conditions

The effect of stretched and unstretched immobilization of a hind limb on the concentration and the metabolism of proteins in the hind-limb muscles of rats was investigated. The animals were divided into three groups: (1) weight-bearing controls, (2) tail-cast-suspended, and (3) suspended, with one hind limb immobilized with the ankle in dorsiflexion (30-40 deg angle) and the other freely moving. It was found that unloading the hind limbs for 6 days by tail cast suspension caused soleus to atrophy and reduced growth of the gastrocnemius and plantaris muscles; unloading resulted in a higher degradation rate and lower synthesis rate in both in vitro and in vivo. Chronic stretch of the unloaded soleus not only prevented its atrophy but led to significant hypertrophy, relative to weight-bearing controls, with increases in both the sarcoplasmic and myofibrillar protein fractions. Immobilizing one ankle in dorsiflexion prevented the inhibition of growth in the plantaris and gastrocnemius muscles due to unloading.

Jaspers, Stephen R.↗
NASA NTRS1995

Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

Chapatwala, Kirit D.↗
NASA NTRS2007

Electrochemically Controlled Reconstitution of Immobilized Ferritins for Bioelectronic Applications

Site-specific reconstituted nanoparticles were fabricated via electrochemically-controlled biomineralization through the immobilization of biomolecules. The work reported herein includes the immobilization of ferritin with various surface modifications, the electrochemical biomineralization of ferritins with different inorganic cores, and the electrocatalytic reduction of oxygen on the reconstituted Pt-cored ferritins. Protein immobilization on the substrate is achieved by anchoring ferritins with dithiobis-N-succinimidyl propionate (DTSP). A reconstitution process of site-specific electrochemical biomineralization with a protein cage loads ferritins with different core materials. The ferritin acts as a nano-scale template, a biocompatible cage, and a separator between the nanoparticles. This first demonstration of electrochemically controlled site-specific reconstitution of biomolecules provides a new tool for biomineralization and opens the way to produce the bio-templated nanoparticles by electrochemical control. The nanosized platinum-cored ferritins on gold displayed good catalytic activity for the electrochemical reduction of oxygen, which is applicable to biofuel cell applications. This results in a smaller catalyst loading on the electrodes for fuel cells or other bioelectronic devices.

Kim, Jae-Woo↗
DOE OSTI2024

Evaluating Iodine Immobilization Technologies: Cermets, Polycermets, and Polyhalmets

The work in this report documents the efforts conducted to assess the feasibility of some of the ideas documented in Pacific Northwest National Laboratory invention disclosure reports (IDRs) including: 1) Iodine capture in polyacrylonitrile (PAN)-containing composite sorbents (32451-E). In this work, the composites evaluated included Ag0, Bi0, Cu0, Bi2S3, and Cu2S embedded in PAN. 2) Metal iodide removal from these sorbents through dissolution in dimethyl sulfoxide (DMSO) (32729-E). In this work, PAN dissolution was evaluated for multiple types of sorbents including Ag-Pan, Bi-PAN, Cu-PAN, Bi2S3-PAN, and Cu2S-PAN. 3) Using metal-sulfide sorbents for iodine capture (32647-E). In this work, the composites evaluated under this IDR included Ag2S, Bi2S3, and Cu2S embedded in PAN. 4) Using low-melting metals to immobilize (encapsulate) iodine-loaded and polymer-containing sorbents into polymer-ceramic-metal (called polycermet) or polymer-halide-metal (called polyhalmet) composite waste forms (32625-E). In this work, the iodine-loaded PAN composites included AgI-PAN, BiI-PAN, and CuI-PAN. 5) Ceramic-metal composite waste form synthesis of polymer-containing materials using low-melting metals like bismuth, tin, or bismuth-tin alloys (32537-E). In this work, the metals evaluated included Bi, 58Bi-42Sn eutectic. 6) Cermets for immobilizing commercial sorbents loaded with radioiodine (32806-E). In this work, AgIX (iodine-loaded silver faujasite zeolite) was evaluated in cermet form.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Geobacter sulfurreducens Immobilized Boron-Doped Diamond Electrodes for Uranium(VI) in Water Electrochemical Bioremediation

The proliferation of nuclear science and technology has resulted in an increase in nuclear waste containing uranium, posing significant risks to both human and environmental health. This study proposes the use of Geobacter sulfurreducens (G. sulfurreducens) modified boron-doped diamond electrodes to facilitate the reduction and removal of uranium(VI) from aqueous media. The bioremediation process involves electrochemically immobilizing the bacteria on a boron-doped diamond electrode (BDD). The immobilization process requires applying reduction potentials ranging from −0.40 to −0.70 V (vs Ag/AgCl (3 M NaCl)), with −0.60 V identified as the optimal potential for effective bacterial modification. The uranium source is provided by a 2.0 mM uranyl acetate solution in G. sulfurreducens growth medium. Scanning electron microscopy (SEM) reveals a highly uniform layer of uranium on the electrode surface. Energy-dispersive X-ray fluorescence spectroscopy (EDS) and cyclic voltammetry (CV) studies confirm the presence of uranium in the system. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) successfully elucidate the reduction process of U(VI) to predominantly U(IV) using a bacteria-electrode coupled system. Additionally, a comparison is made with the electrochemical removal of uranyl ions using the electrodeposition method on unmodified BDD. Results demonstrate the presence of three uranium oxide species (UO 2 , UO 3 , and U 3 O 8 ) on the BDD electrode after experimentation, in contrast to the G. sulfurreducens/BDD assembly, which achieves the predominant reduction of UO 2 2+ to UO 2 with a small quantity of UO 3 as the final species. This study highlights the efficient electrochemical removal of uranyl ions from aqueous media at the G. sulfurreducens/BDD interface through chronoamperometry, presenting a promising approach for remediating sites contaminated with radioactive materials. The findings contribute to the exploration of sustainable alternatives for managing nuclear waste, emphasizing the potential of this electrochemical bioremediation strategy.

Bacteria↗
NASA NTRS1972

Nucleic acid hybridization with RNA immobilized on filter paper.

RNA has been immobilized in a manner suitable for use in molecular hybridization experiments with dissolved RNA or DNA by a nonaqueous solid-phase reaction with carbonyldiimidazole and RNA 'dry coated' on cellulose or, preferably, on previously activated phosphocellulose filters. Immobilization of RNA does not appear to alter its chemical character or cause it to acquire affinity for unspecific RNA or DNA. The versatility and efficiency of this method make it potentially attractive for use in routine analytical or preparative hybridization experiments, among other applications.

Saxinger, W. C.↗
NASA NTRS1974

Utilization of immobilized urease for waste water treatment

The feasibility of using immobilized urease for urea removal from waste water for space system applications is considered, specifically the elimination of the urea toxicity problem in a 30-day Orbiting Frog Otolith (OFO) flight experiment. Because urease catalyzes the hydrolysis of urea to ammonia and carbon dioxide, control of their concentrations within nontoxic limits was also determined. The results of this study led to the use of free urease in lieu of the immobilized urease for controlling urea concentrations. An ion exchange resin was used which reduced the NH3 level by 94% while reducing the sodium ion concentration only 10%.

Husted, R. R.↗
NASA NTRS1980

The effects of adrenalectomy and corticsteroid injection on the fibrinolytic activity of complex heparin compounds in the blood during immobilization

Total non-enzymatic fibrinolytic activity in the blood of rats increased three times in response to stress caused by 30 minute immobilization, and the activity of epinephrine-heparin complex increased nine times. In adrenalectomized animals, which showed a weak response to the same stress, intraperitoneal injection of hydrocortisone 30 minutes prior to immobilization normalized the response. Obtained results indicate that adrenalectomy leads to sharp reduction of heparin complexing with thromogenic proteins and epinephrine, while substitution therapy with hydrocortisone restores anticoagulation system function.

Kudryashov, B. A.↗
NASA NTRS1980

Experimental coronary sclerosis induced by immobilization of rabbits: A new model of arteriosclerosis

A new method for producing arteriosclerosis with coronary insufficiency in rabbits by means of immobilization is described and discussed. The experimentally induced atherosclerosis develops due to hypodynamics imposed by the reduced muscular activity without overloading with exogenous cholesterol. The atherosclerosis and coronary insufficiency are associated. With variations in the duration and extent of immobilization, coronary insufficiency alone or with atherosclerosis can be produced.

Tyavokin, V. V.↗
NASA NTRS1980

Morphological changes in neurons of the hind limb reflex arc during long term immobilization

Twelve adult rabbits were immobilized for 9 to 31 days, followed by histological study of the nerve processes of lumbar vertebra 7 and sacral vertebra 1, the sciatic nerve and the motor endings of the thigh muscles. In the spinal ganglia, dystrophic changes of increasing severity with immobilization time were found, including pericellular edema, vacuolized neuroplasm, pycnotic changes, cytolysis and destruction. Chromatophilic matter decreased and was partly bleached, and amitotic division occurred. A portion of the sciatic nerve fibers were argentophilic, and some fragmentary decomposition occurred. Considerable dystrophic changes occurred in the motor nerve endings.

Tkachenko, Z. Y.↗
NASA NTRS1981

Participation of the hypophyseal-adrenal cortex system in thrombin clearance during immobilization stress

Thrombin marked with I-131 resulted in a considerable increase of the thrombined clearance rate in healthy male rats during stress caused by an immobilization lasting 30 minutes, and in an increase of thrombin clearance occurred by a combination of immobilization and administration of adrenocorticotropin (ACTH). Contrary to ACTH, the thrombin clearance is not stimulated in healthy animals by hydrocortisone. The results of the examination are presented.

Kudryashov, B. A.↗
NASA NTRS1982

Morphometrical investigations on the reproductive activity of the ovaries in rats subjected to immobilization and to motion activity

Wistar-strain white female rats were divided into three groups, with the first group subjected to motion loading, the second used as control, and the third group was immobilized. A considerable reduction in numbers of corpora lutea was observed in the immobilized group, together with smaller numbers of embryos, high percent of embryo mortality, fetal growth retardation, and endometrium disorders. The control group showed no deviation from normal conditions, and there was slight improvement in reproductive activity of animals under motion loading.

Konstantinov, N.↗
NASA NTRS1980

Effects of disuse by limb immobilization on different muscle fiber types

The effects of disuse by limb immobilization on different muscle fiber types are reviewed. It is demonstrated that many changes occurring in atrophying skeletal muscles of young rats can be explained by the duration of the half-lives of muscle proteins. Differences are found to exist in responses of fast- and slow-twitch muscles due to disuse atrophy, and the appearance of plasticity in skeletal muscle begins to occur very soon after changes in the level of contractile activity. Rates of protein degradation increase in slow-twitch muscles at rapidly growing rates after approximately one day of limb immobilization; however, no change in the rates of protein degradation is noted in fast-twitch muscles of young rats.

Booth, F. W.↗