Effect of muscle activation on dynamic responses of neck of pilot during emergency ejection: a finite element study.

To determine the effect of muscle activation on the dynamic responses of the neck of a pilot during simulated emergency ejections. A complete finite element model of the pilot's head and neck was developed and dynamically validated. Three muscle activation curves were designed to simulate different activation times and levels of muscles during pilot ejection: A is the unconscious activation curve of the neck muscles, B is the pre-activation curve, and C is the continuous activation curve. The acceleration-time curves obtained during ejection were applied to the model, and the influence of the muscles on the dynamic responses of the neck was investigated by analyzing both angles of rotation of the neck segments and disc stresses. Muscle pre-activation reduced fluctuations in the angle of rotation in each phase of the neck. Continuous muscle activation caused a 20% increase in the angle of rotation compared to pre-activation. Moreover, it resulted in a 35% increase in the load on the intervertebral disc. The maximum stress on the disc occurred in the C4-C5 phase. Continuous muscle activation increased both the axial load on the neck and the posterior extension angle of rotation of the neck. Muscle pre-activation during emergency ejection has a protective effect on the neck. However, continuous muscle activation increases the axial load and rotation angle of the neck. A complete finite element model of the pilot's head and neck was established and three neck muscle activation curves were designed to investigate the effects of muscle activation time and level on the dynamic response of the pilot's neck during ejection. This increased insights into the protection mechanism of neck muscles on the axial impact injury of the pilot's head and neck.

An electroencephalography-based human-machine interface combined with contralateral C7 transfer in the treatment of brachial plexus injury.

Transferring the contralateral C7 nerve root to the median or radial nerve has become an important means of repairing brachial plexus nerve injury. However, outcomes have been disappointing. Electroencephalography (EEG)-based human-machine interfaces have achieved promising results in promoting neurological recovery by controlling a distal exoskeleton to perform functional limb exercises early after nerve injury, which maintains target muscle activity and promotes the neurological rehabilitation effect. This review summarizes the progress of research in EEG-based human-machine interface combined with contralateral C7 transfer repair of brachial plexus nerve injury. Nerve transfer may result in loss of nerve function in the donor area, so only nerves with minimal impact on the donor area, such as the C7 nerve, should be selected as the donor. Single tendon transfer does not fully restore optimal joint function, so multiple functions often need to be reestablished simultaneously. Compared with traditional manual rehabilitation, EEG-based human-machine interfaces have the potential to maximize patient initiative and promote nerve regeneration and cortical remodeling, which facilitates neurological recovery. In the early stages of brachial plexus injury treatment, the use of an EEG-based human-machine interface combined with contralateral C7 transfer can facilitate postoperative neurological recovery by making full use of the brain's computational capabilities and actively controlling functional exercise with the aid of external machinery. It can also prevent disuse atrophy of muscles and target organs and maintain neuromuscular junction effectiveness. Promoting cortical remodeling is also particularly important for neurological recovery after contralateral C7 transfer. Future studies are needed to investigate the mechanism by which early movement delays neuromuscular junction damage and promotes cortical remodeling. Understanding this mechanism should help guide the development of neurological rehabilitation strategies for patients with brachial plexus injury.

Polydopamine-modified chitin conduits with sustained release of bioactive peptides enhance peripheral nerve regeneration in rats.

The introduction of neurotrophic factors into injured peripheral nerve sites is beneficial to peripheral nerve regeneration. However, neurotrophic factors are rapidly degraded in vivo and obstruct axonal regeneration when used at a supraphysiological dose, which limits their clinical benefits. Bioactive mimetic peptides have been developed to be used in place of neurotrophic factors because they have a similar mode of action to the original growth factors and can activate the equivalent receptors but have simplified sequences and structures. In this study, we created polydopamine-modified chitin conduits loaded with brain-derived neurotrophic factor mimetic peptides and vascular endothelial growth factor mimetic peptides (Chi/PDA-Ps). We found that the Chi/PDA-Ps conduits were less cytotoxic in vitro than chitin conduits alone and provided sustained release of functional peptides. In this study, we evaluated the biocompatibility of the Chi/PDA-Ps conduits. Brain-derived neurotrophic factor mimetic peptide and vascular endothelial growth factor mimetic peptide synergistically promoted proliferation of Schwann cells and secretion of neurotrophic factors by Schwann cells and attachment and migration of endothelial cells in vitro. The Chi/PDA-Ps conduits were used to bridge a 2 mm gap between the nerve stumps in rat models of sciatic nerve injury. We found that the application of Chi/PDA-Ps conduits could improve the motor function of rats and reduce gastrocnemius atrophy. The electrophysiological results and the microstructure of regenerative nerves showed that the nerve conduction function and remyelination was further restored. These findings suggest that the Chi/PDA-Ps conduits have great potential in peripheral nerve injury repair.

Sustained release of exosomes loaded into polydopamine-modified chitin conduits promotes peripheral nerve regeneration in rats.

Exosomes derived from mesenchymal stem cells are of therapeutic interest because of their important role in intracellular communication and biological regulation. On the basis of previously studied nerve conduits, we designed a polydopamine-modified chitin conduit loaded with mesenchymal stem cell-derived exosomes that release the exosomes in a sustained and stable manner. In vitro experiments revealed that rat mesenchymal stem cell-derived exosomes enhanced Schwann cell proliferation and secretion of neurotrophic and growth factors, increased the expression of Jun and Sox2 genes, decreased the expression of Mbp and Krox20 genes in Schwann cells, and reprogrammed Schwann cells to a repair phenotype. Furthermore, mesenchymal stem cell-derived exosomes promoted neurite growth of dorsal root ganglia. The polydopamine-modified chitin conduits loaded with mesenchymal stem cell-derived exosomes were used to bridge 2 mm rat sciatic nerve defects. Sustained release of exosomes greatly accelerated nerve healing and improved nerve function. These findings confirm that sustained release of mesenchymal stem cell-derived exosomes loaded into polydopamine-modified chitin conduits promotes the functional recovery of injured peripheral nerves.

Enhanced recovery after surgery for hip fractures: a systematic review and meta-analysis.

BACKGROUND: Enhanced recovery after surgery (ERAS) programs have achieved promising results in many surgical specialties. However, uncertainty still remains regarding the effect of ERAS on hip fractures. The objective of this review was to investigate the clinical prognosis of ERAS programs in terms of (1) hospital-related endpoints (time to surgery [TTS], length of stay [LOS]), (2) readmission rate, (3) complications, and (4) mortality. METHODS: Published literature was searched in the PubMed, EMBASE, and Cochrane Library databases. All of the included studies met the inclusion criteria. The primary outcomes were TTS and LOS. The secondary outcomes included the 30-day readmission rate, overall complication rate, specific complication rate (delirium and urinary tract infection), and 30-day and 1-year mortality. Language was restricted to English. The data analysis was carried out by Review Manager 5.3. RESULTS: A total of 7 published studies (9869 patients) were finally included, and these were all cohort studies. The meta-analysis showed that the TTS, LOS, and overall complication rate were significantly reduced in the ERAS group compared with the control group (p < 0.01). Moreover, no significant change was found in the 30-day readmission rate or 30-day and 1-year mortality. CONCLUSIONS: ERAS significantly decreases the TTS, LOS, and complication rate without increasing readmission rate and mortality, which adds to the evidence that the implementation of ERAS is beneficial to patients undergoing hip fracture repair surgeries.

Cortical plasticity and nerve regeneration after peripheral nerve injury.

With the development of neuroscience, substantial advances have been achieved in peripheral nerve regeneration over the past decades. However, peripheral nerve injury remains a critical public health problem because of the subsequent impairment or absence of sensorimotor function. Uncomfortable complications of peripheral nerve injury, such as chronic pain, can also cause problems for families and society. A number of studies have demonstrated that the proper functioning of the nervous system depends not only on a complete connection from the central nervous system to the surrounding targets at an anatomical level, but also on the continuous bilateral communication between the two. After peripheral nerve injury, the interruption of afferent and efferent signals can cause complex pathophysiological changes, including neurochemical alterations, modifications in the adaptability of excitatory and inhibitory neurons, and the reorganization of somatosensory and motor regions. This review discusses the close relationship between the cerebral cortex and peripheral nerves. We also focus on common therapies for peripheral nerve injury and summarize their potential mechanisms in relation to cortical plasticity. It has been suggested that cortical plasticity may be important for improving functional recovery after peripheral nerve damage. Further understanding of the potential common mechanisms between cortical reorganization and nerve injury will help to elucidate the pathophysiological processes of nerve injury, and may allow for the reduction of adverse consequences during peripheral nerve injury recovery. We also review the role that regulating reorganization mechanisms plays in functional recovery, and conclude with a suggestion to target cortical plasticity along with therapeutic interventions to promote peripheral nerve injury recovery.

Clinical characteristics of intrahepatic biliary papilloma: A case report.

BACKGROUND: Intrahepatic bile duct papilloma (IPNB) is a rare benign tumour from the bile duct epithelium and has a high malignant transformation rate. Early radical resection can obviously improve the prognosis of patients, but it is difficult to be sure of the diagnosis of IPNB before operating. CASE SUMMARY: This study included 28 patients with intraductal papilloma admitted to the First Hospital of Jilin University from January 2010 to November 2020 and recorded their clinical manifestations, imaging features, complications and prognosis. There were 12 males and 16 females with an average age of 61.36 ± 8.03 years. Most patients had symptoms of biliary obstruction. Biliary dilatation and cystic mass could be seen on imaging. After surgery, IPNB was diagnosed by pathology. CONCLUSION: IPNB is a rare benign tumour in the bile duct. Early diagnosis and timely R0 resection can improve the prognosis of IPNB.

Chitin Nerve Conduits with Three-Dimensional Spheroids of Mesenchymal Stem Cells from SD Rats Promote Peripheral Nerve Regeneration.

Peripheral nerve injury (PNI) is an unresolved medical problem with limited therapeutic effects. Epineurium neurorrhaphy is an important method for treating PNI in clinical application, but it is accompanied by inevitable complications such as the misconnection of nerve fibers and neuroma formation. Conduits small gap tubulization has been proved to be an effective suture method to replace the epineurium neurorrhaphy. In this study, we demonstrated a method for constructing peripheral nerve conduits based on the principle of chitosan acetylation. In addition, the micromorphology, mechanical properties and biocompatibility of the chitin nerve conduits formed by chitosan acetylation were further tested. The results showed chitin was a high-quality biological material for constructing nerve conduits. Previous reports have demonstrated that mesenchymal stem cells culture as spheroids can improve the therapeutic potential. In the present study, we used a hanging drop protocol to prepare bone marrow mesenchymal stem cell (BMSCs) spheroids. Meanwhile, spherical stem cells could express higher stemness-related genes. In the PNI rat model with small gap tubulization, BMSCs spheres exhibited a higher ability to improve sciatic nerve regeneration than BMSCs suspension. Chitin nerve conduits with BMSCs spheroids provide a promising therapy option for peripheral nerve regeneration.

Restraint harness performance during flight maneuvers: a parametric study.

INTRODUCTION: Modern super agile fighter aircraft are capable of producing an increasing multiaxial acceleration environment which can adversely affect the pilot. An evaluation of the performance of the restraint system during flight maneuvers will benefit restraint designs and, thus, the safety of pilots. METHODS: A finite element model of a mannequin with PCU-15/P harness restraint was used in this study to investigate how the factors, such as strap material stiffness, friction, and belt tension, affect the performance of restraint systems during impact along the -Gx, -Gy, and -Gz directions. The corresponding maximum displacement of the mannequin's torso was computed. RESULTS: The mannequin moved beyond 74 mm sideways. The change in friction coefficient (FC) from 0.1 to 0.4 decreased the displacement of the lower torso by less than 6.7%. The displacement of the torso decreased as the stiffness of the strap or tension increased. Displacement decreased by 9.3%, 6.0%, and 2.7% for the lower torso under the Gx impact, as the tightening force increased from 20 N to 80 N gradually. However, this changed slightly when the stiffness arrived at 1 E or the tension increased to 60 N. DISCUSSION: PCU-15/P harness has the poorest performance during side impact and friction plays an unimportant role in affecting its performance. The stiffness of the webbing used in the PCU-15/P harness is sufficiently high. The lap belt has more effect on limiting the movement of the pilot than the shoulder straps, and a tension of 60 N during the adjustment may be enough for conventional flight maneuvers.