Formation of cholinergic synapse-like specializations at developing murine muscle spindles.

Muscle spindles are complex stretch-sensitive mechanoreceptors. They consist of specialized skeletal muscle fibers, called intrafusal fibers, which are innervated in the central (equatorial) region by afferent sensory axons and in both polar regions by efferent γ-motoneurons. We show that AChRs are concentrated at the γ-motoneuron endplate as well as in the equatorial region where they colocalize with the sensory nerve ending. In addition to the AChRs, the contact site between sensory nerve ending and intrafusal muscle fiber contains a high concentration of choline acetyltransferase, vesicular acetylcholine transporter and the AChR-associated protein rapsyn. Moreover, bassoon, a component of the presynaptic cytomatrix involved in synaptic vesicle exocytosis, is present in γ-motoneuron endplates but also in the sensory nerve terminal. Finally, we demonstrate that during postnatal development of the γ-motoneuron endplate, the AChR subunit stoichiometry changes from the γ-subunit-containing fetal AChRs to the ε-subunit-containing adult AChRs, similar and approximately in parallel to the postnatal subunit maturation at the neuromuscular junction. In contrast, despite the onset of ε-subunit expression during postnatal development the γ-subunit remains detectable in the equatorial region by subunit-specific antibodies as well as by analysis of muscle spindles from mice with genetically-labeled AChR γ-subunits. These results demonstrate an unusual maturation of the AChR subunit composition at the annulospiral endings and suggest that in addition to the recently described glutamatergic secretory system, the sensory nerve terminals are also specialized for cholinergic synaptic transmission, synaptic vesicle storage and exocytosis.

Patient-Provider Communication Regarding Referral to Cardiac Rehabilitation.

This study investigated the dynamics of patient-provider communication in the cardiac rehabilitation (CR) referral process, to identify which aspects lead to CR participation. Semi-structured individual interviews were conducted with 31 patients eligible for CR. Questions probed the content and perception of the discussion that patients had with healthcare providers (HCP) regarding CR attendance. The interviews were audiotaped, transcribed, and imported into N6 software for grounded analyses. Key emerging themes were identified: illness perceptions; HCP encouragement; timing of discussion; and ease of referral. CR attenders were apt to self-advocate to ensure their enrollment in CR, whereas nonattenders were more likely to minimize the seriousness of their disease, and less likely to persevere to overcome obstacles in enrolling in a CR program. Surprisingly, the strength of the HCP referral did not influence the decision to attend CR as strongly when compared to the HCP's ability to facilitate enrollment in a CR program.

Formation of somatosensory detour circuits mediates functional recovery following dorsal column injury.

Anatomically incomplete spinal cord injuries can be followed by functional recovery mediated, in part, by the formation of intraspinal detour circuits. Here, we show that adult mice recover tactile and proprioceptive function following a unilateral dorsal column lesion. We therefore investigated the basis of this recovery and focused on the plasticity of the dorsal column-medial lemniscus pathway. We show that ascending dorsal root ganglion (DRG) axons branch in the spinal grey matter and substantially increase the number of these collaterals following injury. These sensory fibers exhibit synapsin-positive varicosities, indicating their integration into spinal networks. Using a monosynaptic circuit tracing with rabies viruses injected into the cuneate nucleus, we show the presence of spinal cord neurons that provide a detour pathway to the original target area of DRG axons. Notably the number of contacts between DRG collaterals and those spinal neurons increases by more than 300% after injury. We then characterized these interneurons and showed that the lesion triggers a remodeling of the connectivity pattern. Finally, using re-lesion experiments after initial remodeling of connections, we show that these detour circuits are responsible for the recovery of tactile and proprioceptive function. Taken together our study reveals that detour circuits represent a common blueprint for axonal rewiring after injury.

Patient-provider communication regarding referral to cardiac rehabilitation.

This study investigated the dynamics of patient-provider communication in the cardiac rehabilitation (CR) referral process, to identify which aspects lead to CR participation. Semi-structured individual interviews were conducted with 31 patients eligible for CR. Questions probed the content and perception of the discussion that patients had with healthcare providers (HCP) regarding CR attendance. The interviews were audiotaped, transcribed, and imported into N6 software for grounded analyses. Key emerging themes were identified: illness perceptions; HCP encouragement; timing of discussion; and ease of referral. CR attenders were apt to self-advocate to ensure their enrollment in CR, whereas nonattenders were more likely to minimize the seriousness of their disease, and less likely to persevere to overcome obstacles in enrolling in a CR program. Surprisingly, the strength of the HCP referral did not influence the decision to attend CR as strongly when compared to the HCP's ability to facilitate enrollment in a CR program.