Search NASA⌕ Search

SEARCH · Search NASA

Results for “atrophy”

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 NTRS1985

Changes in muscle protein composition induced by disuse atrophy - Analysis by two-dimensional electrophoresis

Using 320 g rats, a two-dimensional electrophoretic analysis of muscle proteins in the soleus and EDL muscles from hindlimbs maintained load-free for 10 days is performed. Statistical analysis of the two-dimensional patterns of control and suspended groups reveals more protein alteration in the soleus muscle, with 25 protein differences, than the EDL muscle, with 9 protein differences, as a result of atrophy. Most of the soleus differences reside in minor components. It is suggested that the EDL may also show alteration in its two-dimensional protein map, even though no significant atrophy occurred in muscle wet weight. It is cautioned that strict interpretation of data must take into account possible endocrine perturbations.

Ellis, S.↗
NASA NTRS1990

Age effects on rat hindlimb muscle atrophy during suspension unloading

The effects of hindlimb unloading on muscle mass and biochemical responses were examined and compared in adult (450-g) and juvenile (200-g) rats after 1, 7, or 14 days of whole-body suspension. Quantitatively and qualitatively the soleus, gastrocnemius, plantaris, and extensor digitorum longus (EDL) muscles of the hindlimb exhibited a differential sensitivity to suspension and weightlessness unloading in both adults and juveniles. The red slow-twitch soleus exhibited the most pronounced atrophy under both conditions, with juvenile responses being greater than adult. In contrast, the fast-twitch EDL hypertrophied during suspension and atrophied during weightlessness, with no significant difference between adults and juveniles. Determination of biochemical parameters (total protein, RNA, and DNA) indicates a less rapid rate of response in adult muscles.

Steffen, Joseph M.↗
NASA NTRS1991

Mechanisms of accelerated proteolysis in rat soleus muscle atrophy induced by unweighting or denervation

A hypothesis proposed by Tischler and coworkers (Henriksen et al., 1986; Tischler et al., 1990) concerning the mechanisms of atrophy induced by unweighting or denervation was tested using rat soleus muscle from animals subjected to hindlimb suspension and denervation of muscles. The procedure included (1) measuring protein degradation in isolated muscles and testing the effects of lysosome inhibitors, (2) analyzing the lysosome permeability and autophagocytosis, (3) testing the effects of altering calcium-dependent proteolysis, and (4) evaluating in vivo the effects of various agents to determine the physiological significance of the hypothesis. The results obtained suggest that there are major differences between the mechanisms of atrophies caused by unweighting and denervation, though slower protein synthesis is an important feature common for both.

Tischler, Marc E.↗
NASA NTRS1992

Eccentric exercise training as a countermeasure to non-weight-bearing soleus muscle atrophy

This investigation tested whether eccentric resistance training could prevent soleus muscle atrophy during non-weight bearing. Adult female rats were randomly assigned to either weight bearing +/- intramuscular electrodes or non-weight bearing +/- intramuscular electrodes groups. Electrically stimulated maximal eccentric contractions were performed on anesthetized animals at 48-h intervals during the 10-day experiment. Non-weight bearing significantly reduced soleus muscle wet weight (28-31 percent) and noncollagenous protein content (30-31 percent) compared with controls. Eccentric exercise training during non-weight bearing attenuated but did not prevent the loss of soleus muscle wet weight and noncollagenous protein by 77 and 44 percent, respectively. The potential of eccentric exercise training as an effective and highly efficient counter-measure to non-weight-bearing atrophy is demonstrated in the 44 percent attenuation of soleus muscle noncollagenous protein loss by eccentric exercise during only 0.035 percent of the total non-weight-bearing time period.

Kirby, Christopher R.↗
NASA NTRS1996

Crustaceans as a model for microgravity-induced muscle atrophy

Atrophy of skeletal muscles is a serious problem in a microgravity environment. It is hypothesized that the unloading of postural muscles, which no longer must resist gravity force, causes an accelerated breakdown of contractile proteins, resulting in reduction in muscle mass and strength. A crustacean model using the land crab, Gecarcinus lateralis, to assess the effects of spaceflight on protein meatabolism is presented. The model is compared to a developmentally-regulated atrophy in which a premolt reduction in muscle mass allows the withdrawal of the large claws at molt. The biochemical mechanisms underlying protein breakdown involves both Ca2(+) -dependent and multicatalytic proteolytic enzymes. Crustacean claw muscle can be used to determine the interactions between shortening and unloading at the molecular level.

Mykles, D. L.↗
NASA NTRS2003

Protein turnover in atrophying muscle: from nutritional intervention to microarray expression analysis

PURPOSE OF REVIEW: In response to decreased usage, skeletal muscle undergoes adaptive reductive remodeling due to the decrease in tension on the weight bearing components of the musculo-skeletal system. This response occurs with uncomplicated disuse (e.g. bed rest, space flight), as a secondary consequence of several widely prevalent chronic diseases for which activity is reduced (e.g. chronic obstructive pulmonary disease and chronic heart failure) and is part of the aging process. The problem is therefore one of considerable clinical importance. RECENT FINDINGS: The impaired function and exercise intolerance is related more to the associated muscle wasting rather than to the specific organ system primarily impacted by the disease. Progress has continued in describing the use of anabolic drugs and dietary manipulation. The major advance in the field has been: (i) the discovery of the atrogin-1 gene and (ii) the application of microarray expression analysis and proteomics with the objectives of obtaining comprehensive understanding of the pathways changed with disuse atrophy. SUMMARY: Disuse atrophy is a common clinical problem. There is a need for therapeutic interventions that do not involve exercise. A better understanding of the changes, particularly at the molecular level, could indicate hitherto unsuspected sites for nutritional and pharmacological intervention.

Non-NASA Center↗
NASA NTRS2002

Molecular events in skeletal muscle during disuse atrophy

This review summarizes the current knowledge of the molecular processes underlying skeletal muscle atrophy due to disuse. Because the processes involved with muscle wasting due to illness are similar to disuse, this literature is used for comparison. Areas that are ripe for further study and that will advance our understanding of muscle atrophy are suggested.

NASA Discipline Musculoskeletal↗
NASA NTRS2001

The molecular responses of skeletal muscle satellite cells to continuous expression of IGF-1: implications for the rescue of induced muscular atrophy in aged rats

Approximately 50% of humans older than 85 years have physical frailty due to weak skeletal muscles. This indicates a need for determining mechanisms to combat this problem. A critical cellular factor for postnatal muscle growth is a population of myogenic precursor cells called satellite cells. Given the complex process of sarcopenia, it has been postulated that, at some point in this process, a limited satellite cell proliferation potential could become rate-limiting to the regrowth of old muscles. It is conceivable that if satellite cell proliferative capacity can be maintained or enhanced with advanced age, sarcopenia could potentially be delayed or prevented. Therefore, the purposes of this paper are to describe whether IGF-I can prevent muscular atrophy induced by repeated cycles of hindlimb immobilization, increase the in vitro proliferation in satellite cells from these muscles and, if so, the molecular mechanisms by which IGF-I mediates this increased proliferation. Our results provide evidence that IGF-I can enhance aged muscle regrowth possibly through increased satellite cell proliferation. The results also suggest that IGF-I enhances satellite cell proliferation by decreasing the cell cycle inhibitor, p27Kip1, through the PI3'-K/Akt pathway. These data provide molecular evidence for IGF-I's rescue effect upon aging-associated skeletal muscle atrophy.

NASA Discipline Musculoskeletal↗
NASA NTRS2001

What do we really know about the ubiquitin-proteasome pathway in muscle atrophy?

Studies of many different rodent models of muscle wasting have indicated that accelerated proteolysis via the ubiquitin-proteasome pathway is the principal cause of muscle atrophy induced by fasting, cancer cachexia, metabolic acidosis, denervation, disuse, diabetes, sepsis, burns, hyperthyroidism and excess glucocorticoids. However, our understanding about how muscle proteins are degraded, and how the ubiquitin-proteasome pathway is activated in muscle under these conditions, is still very limited. The identities of the important ubiquitin-protein ligases in skeletal muscle, and the ways in which they recognize substrates are still largely unknown. Recent in-vitro studies have suggested that one set of ubquitination enzymes, E2(14K) and E3(alpha), which are responsible for the 'N-end rule' system of ubiquitination, plays an important role in muscle, especially in catabolic states. However, their functional significance in degrading different muscle proteins is still unclear. This review focuses on the many gaps in our understanding of the functioning of the ubiquitin-proteasome pathway in muscle atrophy, and highlights the strengths and limitations of the different experimental approaches used in such studies.

Review↗
NASA NTRS1987

Hypogravity-induced atrophy of rat soleus and extensor digitorum longus muscles

Prolonged exposure of humans to hypogravity causes weakening of their skeletal muscles. This problem was studied in rats exposed to hypogravity for 7 days aboard Spacelab 3. Hindlimb muscles were harvested 12-16 hours postflight for histochemical, biochemical, and ultrastructural analyses. The majority of the soleus and extensor digitorum longus fibers exhibited simple cell shrinkage. However, approximately 1% of the fibers in flight soleus muscles appeared necrotic. Flight muscle fibers showed increased glycogen, lower subsarcolemmal staining for mitochondrial enzymes, and fewer subsarcolemmal mitochondria. During atrophy, myofibrils were eroded by multiple focal losses of myofilaments; lysosomal autophagy was not evident. Tripeptidylaminopeptidase and calcium-activated protease activities of flight soleus fibers were significantly increased, implying a role in myofibril breakdown. Simple fiber atrophy appears to account for muscle weakening during spaceflight, but fiber necrosis is also a contributing factor.

manned↗
NASA NTRS2009

Cardiac Atrophy and Diastolic Dysfunction During and After Long Duration Spaceflight: Functional Consequences for Orthostatic Intolerance, Exercise Capability and Risk for Cardiac Arrhythmias

Cardiac Atrophy and Diastolic Dysfunction During and After Long Duration Spaceflight: Functional Consequences for Orthostatic Intolerance, Exercise Capability and Risk for Cardiac Arrhythmias (Integrated Cardiovascular) will quantify the extent of long-duration space flightassociated cardiac atrophy (deterioration) on the International Space Station crewmembers.

Levine, Benjamin D.↗
DOE OSTI2023

Cognitively defined Alzheimer's dementia subgroups have distinct atrophy patterns

We sought to determine structural magnetic resonance imaging (MRI) characteristics across subgroups defined based on relative cognitive domain impairments using data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and to compare cognitively defined to imaging-defined subgroups. We used data from 584 people with Alzheimer's disease (AD) (461 amyloid positive, 123 unknown amyloid status) and 118 amyloid-negative controls. We used voxel-based morphometry to compare gray matter volume (GMV) for each group compared to controls and to AD-Memory. There was pronounced bilateral lower medial temporal lobe atrophy with relative cortical sparing for AD-Memory, lower left hemisphere GMV for AD-Language, anterior lower GMV for AD-Executive, and posterior lower GMV for AD-Visuospatial. Formal asymmetry comparisons showed substantially more asymmetry in the AD-Language group than any other group (p = 1.15 × 10 -10 ). For overlap between imaging-defined and cognitively defined subgroups, AD-Memory matched up with an imaging-defined limbic predominant group. MRI findings differ across cognitively defined AD subgroups.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1982

Atrophy of rat skeletal muscles in simulated weightlessness

A hypokinetic rat model was used for elucidation of the mechanism of skeletal muscle wasting which occurs in weightlessness. Rats were suspended from a back-harness with the head tilted downward and the hind limbs totally unloaded. A progressive decrease in the size of the soleus muscle from suspended rats was observed as a function of time. The rate of protein degradation of the homogenates from the soleus muscles of suspended and control animals was not significantly different. The rate of cell-free protein synthesis was severely repressed in the atrophied muscle. An initial rise in the levels of plasma glucose and corticosterone was observed on the second day of suspension, but they subsequently returned to normal values.

Feller, D. D.↗
NASA NTRS1984

Research opportunities in muscle atrophy

A trophy of skeletal muscle; muscle a trophy associated with manned space flight; the nature, causes, and mechanisms of muscle atrophy associated with space flight, selected physiological factors, biochemical aspects, and countermeasures are addressed.

Herbison, G. J.↗
NASA NTRS1988

Evaluation of the endogenous glucocorticoid hypothesis of denervation atrophy

The effects are studied of the oral administration of RU38486, a potent selective glucocorticoid antagonist, on muscle weight, non-collagen protein content, and selected enzyme activities (choline acetyltransferase, glucose 6-phosphate dehydrogenase, and glutamine synthetase) following denervation of rat skeletal muscle. Neither decreases in muscle weight, protein content, and choline acetyltransferase activity, nor increases in the activities of glucose 6-phosphate dehydrogernase and glutamine synthetase were affected by RU38486. These data do not support the hypothesis that denervation atrophy results from enhanced sensitivity of muscle to endogenous glucocorticoids.

Konagaya, Masaaki↗
NASA NTRS1990

An approach to counteracting long-term microgravity-induced muscle atrophy

To find means of alleviating muscle atrophy induced by long-term microgravity, the effects of a 19-week-long heavy-resistance training regime (using either concentric muscle actions only or concentric and eccentric muscle actions) on the strengths of the exercised knee extensor muscle group were investigated in two groups of male human subjects performing two types of training exercises: supine leg press or/and seated knee extension. Results show that a training program in which both the concentric and the eccentric muscle action was performed led to substantially greater increases in maximal muscle strength than when only concentric exercises were performed.

Tesch, P. A.↗
NASA NTRS1992

Intermittent acceleration as a countermeasure to soleus muscle atrophy

The effectiveness of using intermittent acceleration as a countermeasure to muscle atrophy was investigated in rats subjected to 7 days of hindlimb suspension interrupted by daily periods of 1.2 g acceleration, for 15-min periods evenly spaced over 12-hr interval. It was found that this regimen, when repeated for 7 days, failed to completely maintain the mass of soleus muscle, which was 84 percent of control.

D'Aunno, Dominick S.↗