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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.

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30 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Attenuation of skeletal muscle wasting with recombinant human growth hormone secreted from a tissue-engineered bioartificial muscle

Skeletal muscle wasting is a significant problem in elderly and debilitated patients. Growth hormone (GH) is an anabolic growth factor for skeletal muscle but is difficult to deliver in a therapeutic manner by injection owing to its in vivo instability. A novel method is presented for the sustained secretion of recombinant human GH (rhGH) from genetically modified skeletal muscle implants, which reduces host muscle wasting. Proliferating murine C2C12 skeletal myoblasts stably transduced with the rhGH gene were tissue engineered in vitro into bioartificial muscles (C2-BAMs) containing organized postmitotic myofibers secreting 3-5 microg of rhGH/day in vitro. When implanted subcutaneously into syngeneic mice, C2-BAMs delivered a sustained physiologic dose of 2.5 to 11.3 ng of rhGH per milliliter of serum. rhGH synthesized and secreted by the myofibers was in the 22-kDa monomeric form and was biologically active, based on downregulation of a GH-sensitive protein synthesized in the liver. Skeletal muscle disuse atrophy was induced in mice by hindlimb unloading, causing the fast plantaris and slow soleus muscles to atrophy by 21 to 35% ( < 0.02). This atrophy was significantly attenuated 41 to 55% (p < 0.02) in animals that received C2-BAM implants, but not in animals receiving daily injections of purified rhGH (1 mg/kg/day). These data support the concept that delivery of rhGH from BAMs may be efficacious in treating muscle-wasting disorders.

NASA Discipline Musculoskeletal↗
NASA NTRS1993

Co-transplantation of plasmid-transfected myoblasts and myotubes into rat brains enables high levels of gene expression long-term

We have previously proposed the use of primary muscle cells as a "platform," or "vehicle" for intracerebral transgene expression. Brain grafts of minced muscle, or cultured muscle cells persisted in rat brains for at least 6 mo without any decrease in graft size, or tumor formation. Stable, but moderate levels of intracerebral transgene expression were obtained by transplanting plasmid-transfected myotubes in culture. In the present study, high and stable levels of intracerebral transgene expression were achieved by the co-transplantation of plasmid-transfected myoblasts and myotubes in culture. Approximately 5 X 10(5) myoblasts and myotubes were transfected with 10 micrograms pRSVL plasmid DNA, and 30 micrograms Lipofectin (BRL), respectively. They were mixed together (total cell number was 1 million), and stereotactically injected into the caudate nucleus of an adult rat brain. The activity of luciferase, the product of transgene expression, was stable for at least 4 mo, and much higher than the levels in myotube grafts, or co-grafts of myoblasts and minced muscle. Presumably, the myotubes served as a framework on which the myoblasts can form myotubes. The sections of brains transplanted with co-graft of myoblasts, and myotubes transfected with pRSVLac-Z were stained immunofluorescently for beta-galactosidase activity. The muscle grafts contained beta-galactosidase positive myofibers 4 mo after transplantation. Such high and stable levels of in vivo expression after postnatal gene transfer have rarely been achieved. Primary muscle cells are useful vehicle for transgene expression in brains, and potentially valuable for gene therapy of degenerative neurological disorders.

NASA Program Space Biology↗
NASA NTRS2020

2018 NASA Spine Workshop

The NASA Spine Workshop (January 25-26, 2018) provided an evidenced-based, expert review of relevant literature and current knowledge of back pain in space. It reviewed previous findings from the Operational and Research Musculoskeletal Summit of 2005, the NASA Intervertebral Disc Damage Summit of 2009, and the NASA Low Back Pain Meeting of 2015. The primary focus of this workshop was pre-, in-, and post-flight conditioning programs; back pain in space; and post-flight spine disorders. Specifically, the workshop proposed etiologies of space-related back pain/spine disorders. It further focused on methods of evaluating and monitoring spine disorders and how to utilize these methods to advance countermeasures.

Amy J. Kreykes↗
NASA NTRS1996

Hyaluronic acid is increased in the skin and urine in patients with amyotrophic lateral sclerosis

We performed morphological studies of skin and measured glycosaminoglycans in the urine from patients with sporadic amyotrophic lateral sclerosis (ALS) and control subjects. The wide spaces separating collagen bundles reacted strongly with alcian blue stain in ALS patients and stained more markedly as ALS progressed. Staining with alcian blue was virtually eliminated by Streptomyces hyaluronidase. The urinary excretion of hyaluronic acid (HA) (mg/day) was significantly increased (P < 0.01) in ALS patients compared with that of control subjects, and there was a significant positive correlation between the excreted amount of HA and the duration of illness in advanced ALS patients with a duration of more than 2 years from clinical onset (r = 0.72, P < 0.02). We suggest that sporadic ALS includes a metabolic disorder of HA in which an accumulation of HA in the skin is linked to an increased urinary excretion of HA.

NASA Discipline Musculoskeletal↗
NASA NTRS2004

Sensorimotor recovery following spaceflight may be due to frequent square-wave saccadic intrusions

Square-wave jerks (SWJs) are small, involuntary saccades that disrupt steady fixation. We report the case of an astronaut (approximately 140 d on orbit) who showed frequent SWJs, especially postflight, but who showed no impairment of vision or decrement of postflight performance. These data support the view that SWJs do not impair vision because they are paired movements, consisting of a small saccade away from the fixation position followed, within 200 ms, by a corrective saccade that brings the eye back on target. Since many returning astronauts show a decrement of dynamic visual function during postflight locomotion, it seems possible that frequent SWJs improved this astronaut's visual function by providing postsaccadic enhancement of visual fixation, which aided postflight performance. Certainly, frequent SWJs did not impair performance in this astronaut, who had no other neurological disorder.

Case Reports↗
NASA NTRS2000

Quantifying ataxia: ideal trajectory analysis--a technical note

We describe a quantitative method to assess repeated stair stepping stability. In both the mediolateral (ML) and anterioposterior (AP) directions, the trajectory of the subject's center of mass (COM) was compared to an ideal sinusoid. The two identified sinusoids were unique in each direction but coupled. Two dimensionless numbers-the mediolateral instability index (IML) and AP instability index (IAP)-were calculated using the COM trajectory and ideal sinusoids for each subject with larger index values resulting from less stable performance. The COM trajectories of nine nonimpaired controls and six patients diagnosed with unilateral or bilateral vestibular labyrinth hypofunction were analyzed. The average IML and IAP values of labyrinth disorder patients were respectively 127% and 119% greater than those of controls (p<0.014 and 0.006, respectively), indicating that the ideal trajectory analysis distinguishes persons with labyrinth disorder from those without. The COM trajectories also identify movement inefficiencies attributable to vestibulopathy.

Non-NASA Center↗
NASA NTRS1999

Plasma membrane ordering agent pluronic F-68 (PF-68) reduces neurotransmitter uptake and release and produces learning and memory deficits in rats

A substantial body of evidence indicates that aged-related changes in the fluidity and lipid composition of the plasma membrane contribute to cellular dysfunction in humans and other mammalian species. In the CNS, reductions in neuronal plasma membrane order (PMO) (i.e., increased plasma membrane fluidity) have been attributed to age as well as the presence of the beta-amyloid peptide-25-35, known to play an important role in the neuropathology of Alzheimer's disease (AD). These PMO increases may influence neurotransmitter synthesis, receptor binding, and second messenger systems as well as signal transduction pathways. The effects of neuronal PMO on learning and memory processes have not been adequately investigated, however. Based on the hypothesis that an increase in PMO may alter a number of aspects of synaptic transmission, we investigated several neurochemical and behavioral effects of the membrane ordering agent, PF-68. In cell culture, PF-68 (nmoles/mg SDS extractable protein) reduced [3H]norepinephrine (NE) uptake into differentiated PC-12 cells as well as reduced nicotine stimulated [3H]NE release. The compound (800-2400 microg/kg, i.p., resulting in nmoles/mg SDS extractable protein in the brain) decreased step-through latencies and increased the frequencies of crossing into the unsafe side of the chamber in inhibitory avoidance training. In the Morris water maze, PF-68 increased the latencies and swim distances required to locate a hidden platform and reduced the time spent and distance swam in the previous target quadrant during transfer (probe) trials. PF-68 did not impair performance of a well-learned working memory task, the rat delayed stimulus discrimination task (DSDT), however. Studies with 14C-labeled PF-68 indicated that significant (pmoles/mg wet tissue) levels of the compound entered the brain from peripheral (i.p.) injection. No PF-68 related changes were observed in swim speeds or in visual acuity tests in water maze experiments, rotorod performance, or in tests of general locomotor activity. Furthermore, latencies to select a lever in the DSDT were not affected. These results suggest that PF-68 induced deficits in learning and memory without confounding peripheral motor, sensory, or motivational effects at the tested doses. Furthermore, none of the doses induced a conditioned taste aversion to a novel 0.1% saccharin solution indicating a lack of nausea or gastrointestinal malaise induced by the compound. The data indicate that increases in neuronal plasma membrane order may have significant effects on neurotransmitter function as well as learning and memory processes. Furthermore, compounds such as PF-68 may also offer novel tools for studying the role of neuronal PMO in mnemonic processes and changes in PMO resulting from age-related disorders such as AD.

Poloxamer/pharmacology↗
NASA NTRS2000

Invited review: gravitational biology of the neuromotor systems: a perspective to the next era

Earth's gravity has had a significant impact on the designs of the neuromotor systems that have evolved. Early indications are that gravity also plays a key role in the ontogenesis of some of these design features. The purpose of the present review is not to assess and interpret a body of knowledge in the usual sense of a review but to look ahead, given some of the general concepts that have evolved and observations made to date, which can guide our future approach to gravitational biology. We are now approaching an era in gravitational biology during which well-controlled experiments can be conducted for sustained periods in a microgravity environment. Thus it is now possible to study in greater detail the role of gravity in phylogenesis and ontogenesis. Experiments can range from those conducted on the simplest levels of organization of the components that comprise the neuromotor system to those conducted on the whole organism. Generally, the impact of Earth's gravitational environment on living systems becomes more complex as the level of integration of the biological phenomenon of interest increases. Studies of the effects of gravitational vectors on neuromotor systems have and should continue to provide unique insight into these mechanisms that control and maintain neural control systems designed to function in Earth's gravitational environment. A number of examples are given of how a gravitational biology perspective can lead to a clearer understanding of neuromotor disorders. Furthermore, the technologies developed for spaceflight studies have contributed and should continue to contribute to studies of motor dysfunctions, such as spinal cord injury and stroke. Disorders associated with energy support and delivery systems and how these functions are altered by sedentary life styles at 1 G and by space travel in a microgravity environment are also discussed.

Review, Tutorial↗
NASA NTRS1997

Biochemical markers in the assessment of bone disease

As the mean age of our population increases, increasing attention has been paid to the diseases associated with aging, including diseases of the skeleton such as osteoporosis. Effective means of treating and possibly preventing such skeletal disorders are emerging, making their early recognition an important goal for the primary care physician. Although bone density measurements and skeletal imaging studies remain of primary diagnostic importance in this regard, a large number of assays for biochemical markers of bone formation and resorption are being developed that promise to complement the densitometry measurements and imaging studies, providing an assessment of the rates of bone turnover and an earlier evaluation of the effects of therapy. In this review, emphasizing the recent literature, the major biochemical markers currently in use or under active investigation are described, and their application in a number of diseases of the skeleton including osteoporosis is evaluated.

Review↗
NASA NTRS1997

Postural perturbations: new insights for treatment of balance disorders

This article reviews the neural control of posture as understood through studies of automatic responses to mechanical perturbations. Recent studies of responses to postural perturbations have provided a new view of how postural stability is controlled, and this view has profound implications for physical therapy practice. We discuss the implications for rehabilitation of balance disorders and demonstrate how an understanding of the specific systems underlying postural control can help to focus and enrich our therapeutic approaches. By understanding the basic systems underlying control of balance, such as strategy selection, rapid latencies, coordinated temporal spatial patterns, force control, and context-specific adaptations, therapists can focus their treatment on each patient's specific impairments. Research on postural responses to surface translations has shown that balance is not based on a fixed set of equilibrium reflexes but on a flexible, functional motor skill that can adapt with training and experience. More research is needed to determine the extent to which quantification of automatic postural responses has practical implications for predicting falls in patients with constraints in their postural control system.

Review↗
NASA NTRS1995

Connective tissue integrity is lost in vitamin B-6-deficient chicks

The objective of the present investigation was to characterize further the connective tissue disorder produced by pyridoxine (vitamin B-6) deficiency, as previously evidenced by electron microscopy. Following the second post-natal week, fast growing male chicks were deprived of pyridoxine for a 1-mo period. Six weeks post-natally, blood concentrations in the experimental deficiency group had declined to deficiency levels as registered by low concentrations of pyridoxal phosphate (coenzyme form) in erythrocytes, but did not reach levels associated with neurological symptoms. Light microscopic study showed abnormalities in the extracellular matrix of the connective tissues. Collagen cross-links and the aldehyde contents were not significantly lower in cartilage and tendon collagens of vitamin B-6-deficient animals than in age-matched controls; also, their proteoglycan degrading protease and collagenase activities measured in articular cartilages were not greater. Thus, proteolysis was an unlikely alternative mechanism to account for the loss of connective tissue integrity. These results point to the need for further investigation into adhesive properties of collagen associated proteoglycans or other proteins in vitamin B-6-deficient connective tissue.

Non-NASA Center↗
NASA NTRS1992

Imaging of the hip joint. Computed tomography versus magnetic resonance imaging

The authors reviewed the applications and limitations of computed tomography (CT) and magnetic resonance (MR) imaging in the assessment of the most common hip disorders. Magnetic resonance imaging is the most sensitive technique in detecting osteonecrosis of the femoral head. Magnetic resonance reflects the histologic changes associated with osteonecrosis very well, which may ultimately help to improve staging. Computed tomography can more accurately identify subchondral fractures than MR imaging and thus remains important for staging. In congenital dysplasia of the hip, the position of the nonossified femoral head in children less than six months of age can only be inferred by indirect signs on CT. Magnetic resonance imaging demonstrates the cartilaginous femoral head directly without ionizing radiation. Computed tomography remains the imaging modality of choice for evaluating fractures of the hip joint. In some patients, MR imaging demonstrates the fracture even when it is not apparent on radiography. In neoplasm, CT provides better assessment of calcification, ossification, and periosteal reaction than MR imaging. Magnetic resonance imaging, however, represents the most accurate imaging modality for evaluating intramedullary and soft-tissue extent of the tumor and identifying involvement of neurovascular bundles. Magnetic resonance imaging can also be used to monitor response to chemotherapy. In osteoarthrosis and rheumatoid arthritis of the hip, both CT and MR provide more detailed assessment of the severity of disease than conventional radiography because of their tomographic nature. Magnetic resonance imaging is unique in evaluating cartilage degeneration and loss, and in demonstrating soft-tissue alterations such as inflammatory synovial proliferation.

Review↗