Feasibility of allied health assistant management of people with acute hip fracture: protocol for a feasibility randomised controlled trial.

INTRODUCTION: Guidelines for hip fracture care state that patients with hip fracture should be mobilised on the day after surgery and at least once a day thereafter. However, compliance with these guidelines is poor. One approach that would assist physiotherapists to meet mobility guidelines after hip fracture is to delegate the provision of daily mobilisation to allied health assistants under their supervision. Therefore, we plan to conduct a randomised controlled trial to determine the feasibility of an allied health assistant providing daily inpatient rehabilitation to patients with hip fracture. METHODS AND ANALYSIS: Using a parallel group randomised controlled design with one-to-one allocation, participants will be randomly allocated to an experimental group (allied health assistant management) or a comparison group (physiotherapist management). Inclusion criteria are: adult with diagnosis of hip fracture; inpatient in acute hospital; walked independently pre-hip fracture and able to communicate in conversational English. The experimental group will receive routine physiotherapy rehabilitation, including daily mobilisation, from an allied health assistant following initial physiotherapist assessment. The comparison group will receive routine rehabilitation from a physiotherapist. The primary outcome will be the feasibility of allied health assistant management of patients with hip fracture. Feasibility will be determined using the following areas of focus in Bowen's feasibility framework: acceptability (patient satisfaction), demand (proportion of patients who participate), implementation (time allied health assistant/physiotherapist spends with participant, occasions of service) and practicality (cost, adverse events). Staff involved in the implementation of allied health assistant care will be interviewed to explore their perspectives on feasibility. Secondary outcomes include compliance with daily mobilisation guidelines, discharge destination, hospital readmission, falls, functional activity and length of stay. We aim to recruit 50 participants. Descriptive statistics will be used to describe feasibility and mobilisation rates will be calculated using Cox proportional hazards regression to compare compliance with mobilisation guidelines. ETHICS AND DISSEMINATION: Ethics approval was obtained from the Peninsula Health human research ethics committee (HREC/63 005/PH-2020). The findings will be disseminated in peer-reviewed journals and conference presentations. TRAIL REGISTRATION NUMBER: Australian and New Zealand Clinical Trial Registry; ACTRN12620000877987; Pre-results.

A cannabinoid link between mitochondria and memory.

Cellular activity in the brain depends on the high energetic support provided by mitochondria, the cell organelles which use energy sources to generate ATP. Acute cannabinoid intoxication induces amnesia in humans and animals, and the activation of type-1 cannabinoid receptors present at brain mitochondria membranes (mtCB1) can directly alter mitochondrial energetic activity. Although the pathological impact of chronic mitochondrial dysfunctions in the brain is well established, the involvement of acute modulation of mitochondrial activity in high brain functions, including learning and memory, is unknown. Here, we show that acute cannabinoid-induced memory impairment in mice requires activation of hippocampal mtCB1 receptors. Genetic exclusion of CB1 receptors from hippocampal mitochondria prevents cannabinoid-induced reduction of mitochondrial mobility, synaptic transmission and memory formation. mtCB1 receptors signal through intra-mitochondrial Gαi protein activation and consequent inhibition of soluble-adenylyl cyclase (sAC). The resulting inhibition of protein kinase A (PKA)-dependent phosphorylation of specific subunits of the mitochondrial electron transport system eventually leads to decreased cellular respiration. Hippocampal inhibition of sAC activity or manipulation of intra-mitochondrial PKA signalling or phosphorylation of the Complex I subunit NDUFS2 inhibit bioenergetic and amnesic effects of cannabinoids. Thus, the G protein-coupled mtCB1 receptors regulate memory processes via modulation of mitochondrial energy metabolism. By directly linking mitochondrial activity to memory formation, these data reveal that bioenergetic processes are primary acute regulators of cognitive functions.

Neuropathic pain depends upon D-serine co-activation of spinal NMDA receptors in rats.

Activation of N-methyl-d-aspartate (NMDA) receptors is critical for hypersensitivity in chronic neuropathic pain. Since astroglia can regulate NMDA receptor activation by releasing the NMDA receptor co-agonist d-serine, we investigated the role of NMDA receptor and d-serine in neuropathic chronic pain. Male Wistar rats underwent right L5-L6 spinal nerve ligation or sham surgery and were tested for mechanical allodynia and hyperalgesia after 14 days. Acute intrathecal administration of the NMDA receptor antagonist d-AP5 as well as chronic administration of the glia metabolism inhibitor fluoroacetate significantly reduced mechanical allodynia in neuropathic rats. The effect of fluoroacetate was reversed by acutely administered intrathecal d-serine. Degrading d-serine using acute intrathecal administration of d-aminoacid oxidase also reduced pain symptoms. Immunocytochemistry showed that about 70% of serine racemase, the synthesizing enzyme of d-serine, was expressed in astrocyte processes in the superficial laminae of L5 dorsal horn. Serine racemase expression was upregulated in astrocyte processes in neuropathic rats compared to sham rats. These results show that neuropathic pain depends upon glial d-serine that co-activates spinal NMDA receptors.

Phosphorylation of collapsin response mediator protein 2 on Tyr-479 regulates CXCL12-induced T lymphocyte migration.

In the central nervous system, collapsin response mediator protein 2 (CRMP2) is a transducer protein that supports the semaphorin-induced guidance of axons toward their cognate target. However, we previously showed that CRMP2 is also expressed in immune cells and plays a crucial role in T lymphocyte migration. Here we further investigated the molecular mechanisms underlying CRMP2 function in chemokine-directed T-cell motility. Examining Jurkat T-cells treated with the chemokine CXCL12, we found that 1) CXCL12 induces a dynamic re-localization of CRMP2 to uropod, the flexible structure of migrating lymphocyte, and increases its binding to the cytoskeletal protein vimentin; 2) CXCL12 decreases phosphorylation of the glycogen synthase kinase-3beta-targeted residues CRMP2-Thr-509/514; and 3) tyrosine Tyr-479 is a new phosphorylation CRMP2 residue and a target for the Src-family kinase Yes. Moreover, phospho-Tyr-479 increased under CXCL12 signaling while phospho-Thr-509/514 decreased. The functional importance of this tyrosine phosphorylation was demonstrated by Y479F mutation that strongly reduced CXCL12-mediated T-cell polarization and motility as tested in a transmigration model and on neural tissue. We propose that differential phosphorylation by glycogen synthase kinase-3beta and Yes modulates the contribution of CRMP2 to cytoskeletal reorganization during chemokine-directed T-cell migration. In addition to providing a novel mechanism for T lymphocyte motility, our findings reveal CRMP2 as a transducer of chemokine signaling.

T-cells in neuronal injury and repair: semaphorins and related T-cell signals.

There are many parallels between the hematopoietic and the nervous systems in terms of mechanisms regulating their development and functions. In neuroinflammatory diseases, interaction between the immune and nervous systems through shared molecules is suspected to trigger an inappropriate crosstalk and lead to demyelination and axonal loss. Here we focus on semaphorins and their functions in the nervous and immune systems and point out the deleterious effect of an immune semaphorin, semaphorin 4D (Sema4D)/CD100, on oligodendrocyte integrity and survival. We propose immune semaphorins as new candidates involved in the pathogenic mechanisms of neuroinflammatory diseases, promoting demyelination, and impairing neuroregeneration.