Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

Q: Abstract: An orientated substratum has been implicated in the development and regeneration of axons and synapses. We prepared a basement membrane matrix from autogenous striated muscle, used it to repair the sciatic nerve in rats, then investigated the results by histology and electrophysiology. When treated grafts were coaxially aligned with the nerve fascicles functional recovery appeared within 30 days, with good growth of axons into the distal nerve. Grafts with myotubes at right angles to the nerve fascicles supported nerve regeneration but at a slower rate. Grafts of coaxially aligned but untreated muscle allowed axon penetration only through naturally degenerated muscle fibres, with minimal axon penetration of the distal nerve. It is concluded that in the rat a treated graft with correctly orientated empty myotubes can facilitate and guide the regeneration of peripheral nerve after injury and so lead to recolonisation of the distal stump with functional recovery.

A: Animal
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Q: Abstract: Osteoarthrosis is a physiologic imbalance, a "joint failure" similar to "heart failure," in which mechanical factors play a role. The initiation and progression of cartilage damage are distinct phenomena. One of the mechanisms of initiation may be a steep stiffness gradient in the underlying subchondral bone. Progression of cartilage lesions probably requires stiffened subchondral bone. In such situations, transverse stresses at the base of the articular cartilage could cause deep horizontal splits in that tissue. The most likely cause of subchondral stiffening in an otherwise congruent joint is repeated failure of the musculoskeletal peak dynamic force attenuation mechanisms. The health and integrity of the overlying articular cartilage depends on the mechanical properties of its bony bed. In certain models of osteoarthrosis, alterations of the bony bed occur before the cartilage changes and suggest that this can occur in clinical conditions. Stiffening of the subchondral bone also can effect joint conformation, which involves deformation of articular cartilage and bone to create maximum contact areas under load.

A: Animal
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Q: Abstract: Bed-rest deconditioning is suspected to reduce cardiac reserve, possibly by impairing autonomic function. Heart rate response in normal subjects reveals considerable variability, reflected by a relatively broadband interbeat interval power spectrum. A reduction in this autonomically modulated variability would be predicted to cause a narrowing of the spectrum. We retrospectively analyzed data from 10 aerobically conditioned men (age range 35-49 yr) who had undergone orthostatic tolerance testing with lower body negative pressure pre-bed rest and after 7-10 days of bed rest, while on placebo and after intravenous atropine. Spectra were derived by Fourier analysis of 128 interbeat interval data sets. Spectral power was estimated by computing the root-mean-square (rms) values (mean +/- SD) for the band encompassing the 2nd to 64th harmonics from subjects with a sufficient number of beats: placebo rms is 93 +/- 33 ms for pre-bed rest and 84 +/- 38 ms for bed rest (NS, n = 6); atropine rms is 63 +/- 24 ms for pre-bed rest and 40 +/- 23 ms for bed rest (P less than 0.01; n = 7). These data suggest that atropine "unmasks" a deconditioning effect of bed rest in athletic men, evidenced by a reduction in interbeat interval spectral power not apparent with placebo. Spectral analysis offers a useful means of quantitating the effects of bed-rest deconditioning and autonomic perturbations on cardiac dynamics.

A:
Adult
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