Engineering topics

Roy, Roland R.

Publications and source records attributed to Roy, Roland R..

17 records

NASA NTRS2002

Paralysis recovery in humans and model systems

Considerable evidence now demonstrates that extensive functional and anatomical reorganization following spinal cord injury occurs in centers of the brain that have some input into spinal motor pools. This is very encouraging, given the accumulating evidence that new connections formed across spinal lesions may not be initially functionally useful. The second area of advancement in the field of paralysis recovery is in the development of effective interventions to counter axonal growth inhibition. A third area of significant progress is the development of robotic devices to quantify the performance level of motor tasks following spinal cord injury and to 'teach' the spinal cord to step and stand. Advances are being made with robotic devices for mice, rats and humans.

Review↗

NASA NTRS2002

Motoneuron and sensory neuron plasticity to varying neuromuscular activity levels

The size and phenotypic properties of the neural and muscular elements of the neuromuscular unit are matched under normal conditions. When subjected to chronic decreases or increases in neuromuscular activity, however, the adaptations in these properties are much more limited in the neural compared with the muscular elements.

Non-NASA Center↗

NASA NTRS2002

Fiber size, type, and myosin heavy chain content in rhesus hindlimb muscles after 2 weeks at 2 G

BACKGROUND: Fiber atrophy and an increase in the percentage of fast fibers have been observed in Rhesus leg muscles after spaceflight. Hypothesis: Hypergravity will result in muscle fiber hypertrophy and an increase in the percentage of slow fibers. METHODS: Open muscle biopsies were obtained from Rhesus soleus, medial gastrocnemius (MG), and tibialis anterior (TA) muscles before and after 14 d of centrifugation (2 G) and in time-matched controls. Cage activity levels were measured by telemetry. RESULTS: Based on monoclonal antibody binding for myosin heavy chains (MHC), the fastest region of soleus contained a higher proportion of type I+II (27 vs. 13%) and had a tendency for a lower proportion of type I (38 vs. 61%, p = 0.10) fibers after than before centrifugation. There was a higher proportion of type I+II fibers in post- vs. pre-2 G (10 vs. 0.6%) MG biopsies. Fiber type distribution and MHC composition were unaffected in the TA. Overall, mean fiber sizes were unaffected by centrifugation. Average cage activity levels were 36% lower during than before 2 G. CONCLUSIONS: Our hypothesis was rejected. The changes in the proportion of fibers expressing type I MHC are the reverse of that expected with chronic loading of extensors and, paradoxically, are similar to changes observed with chronic unloading, such as occurs during spaceflight, in this primate model. The data are consistent with the observed decrease in total daily activity levels.

Non-NASA Center↗

NASA NTRS1994

Interactive effects of growth hormone and exercise on muscle mass in suspended rats

Measures to attenuate muscle atrophy in rats in response to simulated microgravity (hindlimb suspension (HS)) have been only partially successful. In the present study, hypophysectomized rats were in HS for 7 days, and the effects of recombinant human growth hormone (GH), exercise (Ex), or GH+Ex on the weights, protein concentrations, and fiber cross-sectional areas (CSAs) of hindlimb muscles were determined. The weights of four extensor muscles, i.e., the soleus (Sol), medial (MG) and lateral (LG) gastrocnemius, and plantaris (Plt), and one adductor, i.e., the adductor longus (AL), were decreased by 10-22% after HS. Fiber CSAs were decreased by 34% in the Sol and by 1 17% in the MG after HS. In contrast, two flexors, i.e., the tibialis anterior (TA) and extensor digitorum longus (EDL), did not atrophy. In HS rats, GH treatment alone maintained the weights of the fast extensors (MG, LG, Plt) and flexors (TA, EDL) at or above those of control rats. This effect was not observed in the slow extensor (Sol) or AL. Exercise had no significant effect on the weight of any muscle in HS rats. A combination of GH and Ex treatments yielded a significant increase in the weights of the fast extensors and in the CSA of both fast and slow fibers of the MG and significantly increased Sol weight and CSA of the slow fibers of the Sol. The AL was not responsive to either GH or Ex treatments. Protein concentrations of the Sol and MG were higher only in the Sol of Ex and GH+Ex rats. These results suggest that while GH treatment or intermittent high intensity exercise alone have a minimal effect in maintaining the mass of unloaded muscle, there is a strong interactive effect of these two treatments.

Grindeland, Richard E.↗

NASA NTRS1993

Cosmos 2229

The 6 weeks preflight activities of the Cosmos project during 1993 included: modification of EMG connector to improve the reliability of EMG recording; 24 hour cage activity recording from all but two of the flight animals (monkeys); attempts to record from flight candidates during foot lever task; and force transducer calibrations on all flight candidate animals. The 4 week postflight recordings included: postflight recordings from flight animals; postflight recordings on 3 control (non-flight) animals; postflight recalibration of force transducers on 1 flight and 4 control (non-flight) animals; and attempts to record EMG and video data from the flight animals during postflight locomotion and postural activity. The flight EMG recordings suggest that significant changes in muscle control may occur in spaceflight. It is also clear from recordings that levels of EMG recorded during spaceflight can attain values similar to those measured on earth. Amplifier gain settings should therefore probably not be changed for spaceflight.

Edgerton, V. Reggie↗

NASA NTRS1993

Absence of a growth hormone effect on rat soleus atrophy during a 4-day spaceflight

The effect of a 4-day-long spaceflight on the size and the enzyme properties of soleus fibers of rats and the effects of exogenous growth hormone (GH) on the atrophic response of the soleus muscle were investigated in four groups of rats: (1) control, (2) control plus GH treatment, (3) flight, and (4) flight plus GH treatment. Results showed that the fiber size and the type of myosin heavy chain expressed fibers (but not the metabolic properties) of the soleus were affected by four days of weightlessness and that the effects were not ameliorated by the administration of growth hormone.

Jiang, Bian↗

NASA NTRS1992

Rat soleus muscle fiber responses to 14 days of spaceflight and hindlimb suspension

Morphological and enzymatic responses in fibers of different types were studied in rats after 14 days of spaceflight onboard Cosmos 2044 or hindlimb suspension. Fibers were classified as fast-twitch, slow-twitch, or both fast- and slow-twitch on the basis of the type of myosin heavy chains (MHC). Data obtained indicate that during the 14 days of spaceflight or suspension the protein profiles of 9-14 percents of the slow-twitch fibers reconfigured from typical slow-twitch toward fast switch fibers, while all fibers were dramatically losing total protein. These results were consistent with the data obtained from Cosmos 1887 and Skylab 3. It is suggested that effects of spaceflight on skeletal muscle can be attributed to a dramatic reduction in the level and/or pattern of loading.

Ohira, Yoshi↗

NASA NTRS1992

Adaptation of fibers in fast-twitch muscles of rats to spaceflight and hindlimb suspension

The adaptation of single fibers in medial gastrocnemius (MG), a fast-twitch extensor, and in tibialis anterior (TA), a fast-twitch flexor, was studied after 14 days of spaceflight onboard Cosmos 2044 or hindlimb suspension. Quantitative myosin ATPase activities of single fibers were measured in flight and suspended rats. Each of the enzyme and size measurements were directly correlated within each fiber with respect to its qualitative myosin ATPase staining properties and its expression of fast, slow, or both myosin heavy chains (MHC). The percentage of slow- and fast-twitch fibers of the MG and TA were found to be unchanged. Mean fiber size of all fibers was unaffected after flight or suspension. The ATPase activity in the MG was higher in flight than in control or suspended rats. In comparison to Cosmos 1887 spaceflight, the adaptations in the muscle fibers of the MG were more moderate.

Jiang, Bian↗

NASA NTRS1992

Spaceflight and growth effects on muscle fibers in the rhesus monkey

The effect of a 14-day spaceflight onboard Cosmos 2044 on selected morphological and metabolic properties of single muscle fibers was investigated in a nonhuman primate, Macaca mulatta. It is concluded that the 14-day spaceflight had little impact on fiber size in the soleus (S) and medial gastrocnemius (MG) muscles, whereas it appeared to be a slight decrease in sized in the tibialis anterior (TA). The mean fiber size in the postflight biopsies increased relative to preflight values. The mean fiber succinate dehydrogenase activity was found to decrease in the MG, whereas there was no apparent effect of spaceflight on the s and ta muscles. The differences in response of the S, MG, and TA to spaceflight in monkeys vs rats may be related to a species responsiveness to spaceflight, the manner in which the animals were restrained, and/or the possibility that the ankle musculature was able to function against a load while in space.

Bodine-Fowler, Sue C.↗

NASA NTRS1992

Ventral horn cell responses to spaceflight and hindlimb suspension

Ventral horn cells of the lumbosacral enlargement of the spinal cord were studied focusing on the succinate dehydrogenase (SDH) activity and cross-sectional area of the soma of ventral horn cells which were measured using a computer-aided image-processing system. The relationships between the soma size and SDH activities of lumber ventral horn cells after 14 days of spaceflight (Cosmos 2044) or of hindlimb suspension are considered. Three groups of rats under consideration include control, 14-day spaceflight, and 14-day hindlimb suspension. Data obtained indicate that, compared to the control group, the population distribution of SDH activities in the flight rats shifted toward higher activities, whereas in the suspended rats the distribution shifted toward lower activities. The interactive effects within individual cells showed that there was a higher percentage of small cells with high SDH activities in the flight than in the control or suspended rats. It is suggested that changes in ventral horn cells were due to factors other than simply the absence of weight support.

Jiang, Bian↗

NASA NTRS1990

Influence of 7 days of hindlimb suspension and intermittent weight support on rat muscle mechanical properties

The effect of intermittent periods of weight support on a decrease in mass of the soleus (Sol) and medial gastrocnemius (MG) muscles atrophied by hindlimb suspension (HS) was investigated in rats subjected to continuous HS for seven days or an HS plus intermittent (10 min every 6 hrs of slow walking on a treadmill) weight support (HS-WS). After 7 d HS, the Sol weight relative to body weight was 21 and 9 percent lower in Hs and HS-WS, respectively, than in control rats. Maximum tetanic tension/muscle mass ratio was significantly lower in HS than in controls; the HS-WS rats had values similar to controls, whereas the maximum tetanic tension/muscle weight was significantly elevated in HS-WS compared to controls. Contraction times were 25 percent faster in the Sol and unchanged in the MG of HS rats, indicating that a low-force short-duration exercise regime results in a significant functional recovery in the 'slow' Sol, whereas the 'fast' MG is less affected.

Pierotti, David J.↗

NASA NTRS1989

Effects of periodic weight support on medial gastrocnemius fibers of suspended rats

The effects of seven-day-long hindlimb suspension (HS) and HS plus daily periodic weight support activity on the size and metabolic properties of individual fibers in the medial gastrocnemius (MG) of rats were examined. Sections of muscle tissue removed after seven day suspension were stained quantitatively for succinate dehydrogenase and alpha-glycerophosphate dehydrogenase, and qualitatively for myosin ATPase. It was found that short intermittent periods of weight support had a beneficial effect in maintaining the size and metabolic properties of both dark and light ATPase fibers in the deep regions (i.e., close to the bone) and of dark ATPase fibers in the superficial regions of the MG. The effect was greater in the deep regions.

Graham, Scot C.↗

NASA NTRS1989

Exercise effects on the size and metabolic properties of soleus fibers in hindlimb-suspended rats

The effects of four-week-long hind-limb suspension (HS) of rats on the size the soleus muscle fibers and the activity of succinate dehydrogenase (SDH) in dark and light ATPase fibers were investigated together with the efficacy of an endurance exercise (EX) program (daily treadmill exercise for 1.5 h/day at 20 m/min and a 30-percent grade) in ameliorating HS-induced changes. It was found that, in comparison to age-matched controls, the soleus wet weight decreased by 69 and 30 percent in HS and HS-EX rats, respectively, and the percent of dark ATPase fibers increased from 10 percent in controls to 19 and 17 percent, respectively. The values of the integrated fiber activity (activity/min times muscle area) showed a net loss of SDH in both the light and dark ATPase fibers of HS rats, but only in the light ATPase fibers of the HS-EX rats, indicating that exercise ameliorated but did not prevent the muscle fiber atrophy induced by HS.

Graham, Scot C.↗

NASA NTRS1988

Periodic weight support effects on rat soleus fibers after hindlimb suspension

The morphological and histochemical properties of rat soleus muscles were investigated following one week of hindlimb suspension. Short-duration daily weight support activity is shown to ameliorate, but not prevent, soleus atrophy induced by hindlimb suspension. The results indicate that fiber cross-sectional area is more responsive to periodic weight support in dark than light ATPas fibers, and that muscle fiber atrophy need not be associated with a loss in succinate dehydrogenase activity.

Hauschka, Edward O.↗

NASA NTRS1988

Adaptation of bone and tendon to prolonged hindlimb suspension in rats

The effect of a sustained deprivation of ground reaction forces on mineralized and soft connective tissues was investigated in rats subjected to 28-d-long hind-limb suspension. The results of morphological and biochemical studies carried out on femurs and patellar tendons obtained from suspended and nonsuspended 110-d-old rats showed that prolonged suspension led to an increase of the minimum diameter of the femur middiaphysis (by 12 percent), without any significant alterations in cortical area, density, mineral and collagen concentrations, femur wet weight, length, and DNA and uronic acid concentrations. However, in the patellar tendons of suspended rats, the collagen and proteoglycan concentrations were 28 percent lower than in tendons obtained from nonsuspended animals. These results suggest that ground reaction forces are important for the maintenance of cortical bone and patellar tendon homeostasis during weight-bearing conditions.

Vailas, Arthur C.↗

NASA NTRS1987

Size and metabolic properties of single muscle fibers in rat soleus after hindlimb suspension

The effect of 28-day-long hind-limb suspension (HS) combined with 10 daily forceful lengthening contractions of the limb on the morphological and metabolic properties of individual fibers of the soleus was studied in rats, using quantitative histochemical techniques. Compared with nonsuspended controls (CON), soleus wet weights of HS rats were decreased by 49 percent; the fibers staining lightly for myosin ATPase ('light-ATPase' fibers) atrophied more than the 'dark-ATPase' fibers. Single-fiber alpha-glycerophosphate dehydrogenase (GPD) and succinate dehydrogenase (SDH) activities were higher in HS than in CON rats. Daily forceful lengthening contractions did not prevent the HS-induced changes. The results support the view that the soleus fibers can change from a slow-twitch oxidative to a fast-twitch oxidative-glycolytic profile, but rarely to a fast-twitch glycolytic one, and that the SDH and GPD activities per volume of tissue can be increased even when there are severe losses of contractile proteins.

Hauschka, Edward O.↗

NASA NTRS1987

Size and metabolic properties of fibers in rat fast-twitch muscles after hindlimb suspension

The effect of hind-limb suspension (HS) on single fibers of the medial gastrocnemius (MG) and the tibialis anterior (TA) muscles were studied in rats. Fiber area and the activities of succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (GPD) were determined in tissue sections using an image analysis system. After 28 days of HS, the MG atrophied 28 percent, whereas the TA weight was maintained. Both dark- and light-ATPase fibers in the deep region of the MG had decreased cross-sectional areas following HS, with the atrophic response being twice as great in the light-ATPase fibers than in the dark-ATPase fibers. Following HS, mean SDH activities of both fiber types were significantly lower in the MG and TA than in the CON; by contrast, mean GPD activities were either maintained at the CON level or were higher in both MG and TA muscles. The data suggest an independence of the mechanisms determining the muscle fiber size and the metabolic adaptations associated with HS.

Roy, Roland R.↗