Patients with early infantile epileptic encephalopathy (EIEE) are at increased risk for sudden unexpected death in epilepsy (SUDEP). De novo mutations of the sodium channel gene SCN8A, encoding the sodium channel Na v 1.6, result in EIEE13 (OMIM 614558), which has a 10% risk of SUDEP. Here, we investigated the cardiac phenotype of a mouse model expressing the gain of function EIEE13 patient mutation p.Asn1768Asp in Scn8a (Na v 1.6-N1768D). We tested Scn8a N1768D/+ mice for alterations in cardiac excitability. We observed prolongation of the early stages of action potential (AP) repolarization in mutant myocytes vs. controls. Scn8a N1768D/+ myocytes were hyperexcitable, with a lowered threshold for AP firing, increased incidence of delayed afterdepolarizations, increased calcium transient duration, increased incidence of diastolic calcium release, and ectopic contractility. Calcium transient duration and diastolic calcium release in the mutant myocytes were tetrodotoxin-sensitive. A selective inhibitor of reverse mode Na/Ca exchange blocked the increased incidence of diastolic calcium release in mutant cells. Scn8a N1768D/+ mice exhibited bradycardia compared with controls. This difference in heart rate dissipated after administration of norepinephrine, and there were no differences in heart rate in denervated ex vivo hearts, implicating parasympathetic hyperexcitability in the Scn8a N1768D/+ animals. When challenged with norepinephrine and caffeine to simulate a catecholaminergic surge, Scn8a N1768D/+ mice showed ventricular arrhythmias. Two of three mutant mice under continuous ECG telemetry recording experienced death, with severe bradycardia preceding asystole. Thus, in addition to central neuron hyperexcitability, Scn8a N1768D/+ mice have cardiac myoycte and parasympathetic neuron hyperexcitability. Simultaneous dysfunction in these systems may contribute to SUDEP associated with mutations of Scn8a. sodium channel | epilepsy | arrhythmia | channelopathy | mutation

Purpose of Review-Fractures are painful and disabling injuries that can occur due to trauma, especially when compounded with pathologic conditions, such as osteoporosis in older adults. It is well documented that acute pain management plays an integral role in the treatment of orthopedic patients. There is no current therapy available to completely control post-fracture pain that does not interfere with bone healing or have major adverse effects. In this review, we focus on recent advances in the understanding of pain behaviors post-fracture.Recent Findings-We review animal models of bone fracture and the assays that have been developed to assess and quantify spontaneous and evoked pain behaviors, including the two most commonly used assays: dynamic weight bearing and von Frey testing to assess withdrawal from a cutaneous (hindpaw) stimulus. Additionally, we discuss the assessment and quantification of fracture pain in the clinical setting, including the use of numeric pain rating scales, satisfaction with pain relief, and other biopsychosocial factor measurements. We review how pain behaviors in animal models and clinical cases can change with the use of current pain management therapies. We conclude by discussing the use of pain behavioral analyses in assessing potential therapeutic treatment options for addressing acute and chronic fracture pain without compromising fracture healing.Summary-There currently is a lack of effective treatment options for fracture pain that reliably relieve pain without potentially interfering with bone healing. Continued development and verification of reliable measurements of fracture pain in both pre-clinical and clinical settings is an essential aspect of continued research into novel analgesic treatments for fracture pain.Terms of use and reuse: academic research for non-commercial purposes, see here for full terms. http://www.springer.com/gb/openaccess/authors-rights/aam-terms-v1 *

OBJECTIVE In 2021, several patients across the United States received bone allograft contaminated with Mycobacterium tuberculosis (TB). TB is typically a pulmonary infection with many possible extrapulmonary manifestations, including skeletal tuberculosis. However, TB is a rare causative organism of postoperative surgical site infection. Iatrogenic skeletal TB infections are not widely reported in the medical literature; therefore, treatment and associated outcomes are relatively unknown. In this series, the authors report 6 cases of patients who received a mesenchymal stem cell–enhanced bone graft infected with TB at their institution, including the clinical courses, imaging findings, management plans, and outcomes at 1 year postoperatively. METHODS A retrospective review was performed of 6 consecutive patients who underwent spinal fusion surgery at the authors’ institution and received bone graft from a lot contaminated with TB. Collected data included patient demographic characteristics, indications for surgery, surgical procedures performed, timing of contamination discovery, medical treatment, and follow-up information including reoperation, healing progress, and imaging findings. RESULTS Five of 6 patients (83.3%) eventually tested positive for TB via interferon-gamma release assay or wound culture. They experienced significant complications, including surgical site infections with neck swelling, pain, dysphagia, and wound dehiscence. Extensive soft-tissue infection was common; however, significant bony involvement was not observed. Surgical wound debridement was required in 4 patients, and all patients received medical management with standard RIPE (rifampin, isoniazid pyrazinamide, pyridoxine, and ethambutol) therapy for 8 weeks with extension of rifampin and isoniazid for scheduled 12 months. All patients (excluding 1 patient who died of COVID-19) showed signs of improvement with adequately healing wounds at the most recent follow-up at a median (range) of 12 (6–13) months postoperatively. To date, no patients have developed pulmonary TB. CONCLUSIONS Direct inoculation with TB via contaminated bone grafts resulted in a high rate of severe soft-tissue infection, although extensive skeletal and pulmonary involvement has not been observed at 1 year postoperatively; this review includes the longest reported follow-up period for this TB outbreak. Medical management remains the mainstay of therapy for these patients, with most patients showing recovery with oral antibiotic therapy. The severity of these infections arising from mesenchymal stem cell–containing bone allografts that undergo an alternative sterilization process than standard allografts raises concerns regarding the added risks of infection, which should be weighed against the expected benefits of these grafts.

Marburg virus (MARV) is a lipid-enveloped negative sense single stranded RNA virus, which can cause a deadly hemorrhagic fever. MARV encodes seven proteins, including VP40 (mVP40), a matrix protein that interacts with the cytoplasmic leaflet of the host cell plasma membrane. VP40 traffics to the plasma membrane inner leaflet, where it assembles to facilitate the budding of viral particles. VP40 is a multifunctional protein that interacts with several host proteins and lipids to complete the viral replication cycle, but many of these host interactions remain unknown or are poorly characterized. In this study, we investigated the role of a hydrophobic loop region in the carboxy-terminal domain (CTD) of mVP40 that shares sequence similarity with the CTD of Ebola virus VP40 (eVP40). These conserved hydrophobic residues in eVP40 have been previously shown to be critical to plasma membrane localization and membrane insertion. An array of cellular experiments and confirmatory in vitro work strongly suggests proper orientation and hydrophobic residues (Phe281, Leu283, and Phe286) in the mVP40 CTD are critical to plasma membrane localization. In line with the different functions proposed for eVP40 and mVP40 CTD hydrophobic residues, molecular dynamics simulations demonstrate large flexibility of residues in the EBOV CTD whereas conserved mVP40 hydrophobic residues are more restricted in their flexibility. This study sheds further light on important amino acids and structural features in mVP40 required for its plasma membrane localization as well as differences in the functional role of CTD amino acids in eVP40 and mVP40.

OBJECTIVE Tethered cord syndrome (TCS) is a clinical and radiographic diagnosis of pathological stretching of the spinal cord leading to progressive loss of neurological function. The gold standard treatment for TCS is a tethered cord release. However, detethering involves significant risks of spinal cord injury and high rates of retethering. To mitigate these risks, the concept of spinal column shortening (SCS) to decrease spinal cord tension has become an alternative to detethering. In this study, the authors applied SCS to a pediatric and emerging adult population affected by secondary TCS. METHODS A retrospective review of a prospective database at the authors’ tertiary pediatric institution was performed. The Pediatric Quality of Life Inventory, patient- and parent-reported outcomes, and urodynamics were used to evaluate the outcomes of TCS treated with SCS. RESULTS A total of 41 patients with secondary TCS were treated with SCS. The average age at the time of surgery was 15.9 years (range 5–55 years). Preoperative symptoms evaluated included pain (33 patients), weakness (30 patients), and bladder/bowel dysfunction (39 patients). The most common level of spinal column osteotomy was T12, with spinal fusion between T10 and L2. The mean follow-up time was 22.6 months (range 8–45 months). For patients with at least 12 months of follow-up, subjective clinical improvements were reported in 21/23 (91.3%) of those with preoperative pain (p < 0.01); in 16/24 (66.7%) of patients with weakness (p < 0.01), and in 15/29 (51.7%) of those with bladder/bowel dysfunction (p < 0.01). The median differences in initial and most recent Pediatric Quality of Life Inventory results were +5 for patient-reported scores (n = 19, p = 0.04) and +5 for parent-reported scores (n = 19, p = 0.08). Formal urodynamics performed at a median of 3.5 months after surgery documented stable to improved bladder function in 16/17 patients, with a median improvement in one classification category (n = 17, p = 0.01). CONCLUSIONS SCS continues to represent a safe and efficacious alternative to traditional spinal cord untethering for TCS in children and emerging adults, as documented by objective formal urodynamics and patient- and parent-reported outcomes.