Stereotactic body radiotherapy for treatment of spinal metastasis: A systematic review of the literature.

Background: Advances in local and systemic therapies continue to improve overall survival for patients with cancer, increasing the incidence of spine metastases. Up to 15% of patients with solid tumors develop spinal metastases. Spinal metastases can be particularly devastating for quality of life given the potential pain, neurological deficits from spinal cord compression or cauda equina syndrome, spinal instability, and pathological fractures that may result. Stereotactic body radiotherapy (SBRT) with or without adding less invasive surgical techniques for stabilization or separation has gained favor. SBRT uses smaller, more precise treatment volumes, allowing for higher doses per fracture, thus increasing ablative abilities. Methods: We conducted a systematic review using MEDLINE, Embase (Elsevier), and Web of Science to identify all articles investigating the effectiveness of SBRT in providing local disease control, pain control, and relief of spinal cord compression for patients with metastatic disease of the spine. Results: The review yielded 84 articles that met inclusion criteria. The evidence indicates SBRT provides excellent local control and pain control for patients with spine metastesis, and this remains true for patients with spinal cord compression managed with surgical separation followed by postoperative spine SBRT. Conclusion: While not all patients are appropriate candidates for SBRT, carefully considering appropriate frameworks that consider the patient's overall prognosis can guide a multidisciplinary team toward the patients who will benefit the most from this treatment modality.

Axon guidance genes are regulated by TDP-43 and RGNEF through long-intron removal.

Rho guanine nucleotide exchange factor (RGNEF) is a guanine nucleotide exchange factor (GEF) mainly involved in regulating the activity of Rho-family GTPases. It is a bi-functional protein, acting both as a guanine exchange factor and as an RNA-binding protein. RGNEF is known to act as a destabilizing factor of neurofilament light chain RNA (NEFL) and it could potentially contribute to their sequestration in nuclear cytoplasmic inclusions. Most importantly, RGNEF inclusions in the spinal motor neurons of ALS patients have been shown to co-localize with inclusions of TDP-43, the major well-known RNA-binding protein aggregating in the brain and spinal cord of human patients. Therefore, it can be hypothesized that loss-of-function of both proteins following aggregation may contribute to motor neuron death/survival in ALS patients. To further characterize their relationship, we have compared the transcriptomic profiles of neuronal cells depleted of TDP-43 and RGNEF and show that these two factors predominantly act in an antagonistic manner when regulating the expression of axon guidance genes. From a mechanistic point of view, our experiments show that the effect of these genes on the processivity of long introns can explain their mode of action. Taken together, our results show that loss-of-function of factors co-aggregating with TDP-43 can potentially affect the expression of commonly regulated neuronal genes in a very significant manner, potentially acting as disease modifiers. This finding further highlights that neurodegenerative processes at the RNA level are the result of combinatorial interactions between different RNA-binding factors that can be co-aggregated in neuronal cells. A deeper understanding of these complex scenarios may lead to a better understanding of pathogenic mechanisms occurring in patients, where more than one specific protein may be aggregating in their neurons.

Epigenetics in the formation of pathological aggregates in amyotrophic lateral sclerosis.

The progressive degeneration of motor neurons in amyotrophic lateral sclerosis (ALS) is accompanied by the formation of a broad array of cytoplasmic and nuclear neuronal inclusions (protein aggregates) largely containing RNA-binding proteins such as TAR DNA-binding protein 43 (TDP-43) or fused in sarcoma/translocated in liposarcoma (FUS/TLS). This process is driven by a liquid-to-solid phase separation generally from proteins in membrane-less organelles giving rise to pathological biomolecular condensates. The formation of these protein aggregates suggests a fundamental alteration in the mRNA expression or the levels of the proteins involved. Considering the role of the epigenome in gene expression, alterations in DNA methylation, histone modifications, chromatin remodeling, non-coding RNAs, and RNA modifications become highly relevant to understanding how this pathological process takes effect. In this review, we explore the evidence that links epigenetic mechanisms with the formation of protein aggregates in ALS. We propose that a greater understanding of the role of the epigenome and how this inter-relates with the formation of pathological LLPS in ALS will provide an attractive therapeutic target.

Phase Separation of SARS-CoV-2 Nucleocapsid Protein with TDP-43 Is Dependent on C-Terminus Domains.

The SARS-CoV-2 nucleocapsid protein (N protein) is critical in viral replication by undergoing liquid-liquid phase separation to seed the formation of a ribonucleoprotein (RNP) complex to drive viral genomic RNA (gRNA) translation and in suppressing both stress granules and processing bodies, which is postulated to increase uncoated gRNA availability. The N protein can also form biomolecular condensates with a broad range of host endogenous proteins including RNA binding proteins (RBPs). Amongst these RBPs are proteins that are associated with pathological, neuronal, and glial cytoplasmic inclusions across several adult-onset neurodegenerative disorders, including TAR DNA binding protein 43 kDa (TDP-43) which forms pathological inclusions in over 95% of amyotrophic lateral sclerosis cases. In this study, we demonstrate that the N protein can form biomolecular condensates with TDP-43 and that this is dependent on the N protein C-terminus domain (N-CTD) and the intrinsically disordered C-terminus domain of TDP-43. This process is markedly accelerated in the presence of RNA. In silico modeling suggests that the biomolecular condensate that forms in the presence of RNA is composed of an N protein quadriplex in which the intrinsically disordered TDP-43 C terminus domain is incorporated.

Mitigation of TDP-43 toxic phenotype by an RGNEF fragment in amyotrophic lateral sclerosis models.

Aggregation of the RNA-binding protein TAR DNA binding protein (TDP-43) is a hallmark of TDP-proteinopathies including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). As TDP-43 aggregation and dysregulation are causative of neuronal death, there is a special interest in targeting this protein as a therapeutic approach. Previously, we found that TDP-43 extensively co-aggregated with the dual function protein GEF (guanine exchange factor) and RNA-binding protein rho guanine nucleotide exchange factor (RGNEF) in ALS patients. Here, we show that an N-terminal fragment of RGNEF (NF242) interacts directly with the RNA recognition motifs of TDP-43 competing with RNA and that the IPT/TIG domain of NF242 is essential for this interaction. Genetic expression of NF242 in a fruit fly ALS model overexpressing TDP-43 suppressed the neuropathological phenotype increasing lifespan, abolishing motor defects and preventing neurodegeneration. Intracerebroventricular injections of AAV9/NF242 in a severe TDP-43 murine model (rNLS8) improved lifespan and motor phenotype, and decreased neuroinflammation markers. Our results demonstrate an innovative way to target TDP-43 proteinopathies using a protein fragment with a strong affinity for TDP-43 aggregates and a mechanism that includes competition with RNA sequestration, suggesting a promising therapeutic strategy for TDP-43 proteinopathies such as ALS and FTD.

Dynamic Localization of Paraspeckle Components under Osmotic Stress.

Paraspeckles are nuclear condensates formed by NEAT1_2 lncRNA and different RNA-binding proteins. In general, these membraneless organelles function in the regulation of gene expression and translation and in miRNA processing, and in doing this, they regulate cellular homeostasis and mediate pro-survival in the cell. Despite evidence showing the importance of paraspeckles in the stress response, the dynamics of paraspeckles and their components under conditions of osmotic stress remain unknown. We exposed HEK293T cells to sorbitol and examined NEAT1_2 expression using real-time PCR. Localization and quantification of the main paraspeckle components, NEAT1_2, PSPC1, NONO, and SFPQ, in different cellular compartments was performed using smFISH and immunofluorescence. Our findings showed a significant decrease in total NEAT1_2 expression in cells after osmotic stress. Sorbitol shifted the subcellular localization of NEAT1_2, PSPC1, NONO, and SFPQ from the nucleus to the cytoplasm and decreased the number and size of NEAT1_2 foci in the nucleus. PSPC1 formed immunoreactive cytoplasmic fibrils under conditions of osmotic stress, which slowly disassembled under recovery. Our study deepens the paraspeckle dynamics in response to stress, suggesting a novel role for NEAT1_2 in the cytoplasm in osmotic stress and physiological conditions.

A methodological primer of extracellular vesicles isolation and characterization via different techniques.

We present four different protocols of varying complexity for the isolation of cell culture-derived extracellular vesicles (EVs)/exosome-enriched fractions with the objective of providing researchers with easily conducted methods that can be adapted for many different uses in various laboratory settings and locations. These protocols are primarily based on polymer precipitation, filtration and/or ultracentrifugation, as well as size-exclusion chromatography (SEC) and include: (i) polyethylene glycol and sodium chloride supplementation of the conditioned medium followed by low-speed centrifugation; (ii) ultracentrifugation of conditioned medium; (iii) filtration of conditioned media through a 100-kDa exclusion filter; and (iv) isolation using a standard commercial kit. These techniques can be followed by further purification by ultracentrifugation, sucrose density gradient centrifugation, or SEC if needed and the equipment is available. HEK293 and SH-SY5Y cell cultures were used to generate conditioned medium containing exosomes. This medium was then depleted of cells and debris, filtered through a 0.2-µM filter, and supplemented with protease and RNAse inhibitors prior to exosomal isolation. The purified EVs can be used immediately or stably stored at 4°C (up to a week for imaging or using intact EVS downstream) or at -80°C for extended periods and then used for biochemical study. Our aim is not to compare these methodologies but to present them with descriptors so that researchers can choose the "best method" for their work under their individual conditions.

A technique for repeated blood and cerebrospinal fluid sampling from individual rats over time without the need for repeated anesthesia.

Ethical animal use follows the 3R's: Replacement, Reduction and Refinement. Here, we present the use of simultaneous jugular vein and cisterna magna catheterization via a port system in rats for repeated fluid sampling for 14 consecutive days without loss of catheter patency. This technique allows repeated intra-animal sampling without anesthesia and, if used with pooling samples from a cohort of animals, replaces the need for terminal collections for sufficient sample volumes.

Association of plasma biomarkers with cognition, cognitive decline, and daily function across and within neurodegenerative diseases: Results from the Ontario Neurodegenerative Disease Research Initiative.

INTRODUCTION: We investigated whether novel plasma biomarkers are associated with cognition, cognitive decline, and functional independence in activities of daily living across and within neurodegenerative diseases. METHODS: Glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), phosphorylated tau (p-tau)181 and amyloid beta (Aß)42/40 were measured using ultra-sensitive Simoa immunoassays in 44 healthy controls and 480 participants diagnosed with Alzheimer's disease/mild cognitive impairment (AD/MCI), Parkinson's disease (PD), frontotemporal dementia (FTD) spectrum disorders, or cerebrovascular disease (CVD). RESULTS: GFAP, NfL, and/or p-tau181 were elevated among all diseases compared to controls, and were broadly associated with worse baseline cognitive performance, greater cognitive decline, and/or lower functional independence. While GFAP, NfL, and p-tau181 were highly predictive across diseases, p-tau181 was more specific to the AD/MCI cohort. Sparse associations were found in the FTD and CVD cohorts and for Aß42/40 . DISCUSSION: GFAP, NfL, and p-tau181 are valuable predictors of cognition and function across common neurodegenerative diseases, and may be useful in specialized clinics and clinical trials.

New metal-organic framework coated sodium alginate for the delivery of curcumin as a sustainable drug delivery and cancer therapy system.

The utilization of biocompatible drug delivery systems with extended drug release capabilities is highly advantageous in cancer therapy, as they can mitigate adverse effects. To establish such a biocompatible system with prolonged drug release behavior, researchers developed an innovative drug carrier. In this study, a sustainable approach was employed to synthesize a new zinc-based metal-organic framework (Zn-MOF) through the reaction between synthesized Schiff base ligands and zinc ions. Comprehensive analyses, including FT-IR, XRD, SEM, BET surface area, and TGA techniques, were employed to thoroughly characterize the frameworks. Following comprehensive characterization, curcumin (CUR) was loaded onto the Zn-MOF, resulting in CUR entrapment efficiency and loading capacity of 79.23 % and 26.11 %, respectively. In vitro evaluations of CUR release from CUR@MOF exhibited controlled release patterns, releasing 78.9 % and 50.0 % of CUR at pH 5.0 and pH 7.4, respectively. To mitigate initial burst release, a coating of the biopolymer sodium alginate (SA) was applied to CUR@Zn-MOF. In vitro CUR release tests indicated that SA/CUR@Zn-MOF outperformed pristine CUR@Zn-MOF. The release of CUR conformed to the Korsmeyer-Peppas model, displaying non-Fickian diffusion. Furthermore, an in vitro cytotoxicity study clearly demonstrated the potent anti-tumor activity of the synthesized CUR@Zn-MOF attributed to its controlled release of CUR. This led to the induction of apoptotic effects and cell death across HeLa, HEK293, and SH-SY5Y cell lines. These findings strongly suggest that the developed pH-sensitive carriers hold remarkable potential as targeted vehicles for drug delivery in cancer therapy.

Upregulation of LRRK2 following traumatic brain injury does not directly phosphorylate Thr175 tau.

Phosphorylated microtubule-associated protein tau (tau) aggregates are a pathological hallmark of various neurodegenerative diseases, including chronic traumatic encephalopathy and amyotrophic lateral sclerosis with cognitive impairment. While there are many residues phosphorylated on tau, phosphorylation of threonine 175 (pThr175 tau) has been shown to initiate fibril formation in vitro and is present in pathological tau aggregates in vivo. Given this, preventing Thr175 tau phosphorylation presents a potential approach to reduce fibril formation; however, the kinase(s) acting on Thr175 are not yet fully defined. Using a single controlled cortical impact rodent model of traumatic brain injury (TBI), which rapidly induces Thr175 tau phosphorylation, we observed an upregulation and alteration in subcellular localization of leucine-rich repeat kinase 2 (LRRK2), a kinase that has been implicated in tau phosphorylation. LRRK2 upregulation was evident by one-day post-injury and persisted to day 10. The most notable changes were observed in microglia at the site of injury in the cortex. To determine if the appearance of pThr175 tau was causally related to the upregulation of LRRK2 expression, we examined the ability of LRRK2 to phosphorylate Thr175in vitro by co-transfecting 2N4R human WT-tau with either LRRK2-WT, constitutively-active LRRK2-G2019S or inactive LRRK2-3XKD. We found no significant difference in the level of pThr175 tau between the overexpression of LRRK2-WT, -G2019S or -3XKD, suggesting LRRK2 does not phosphorylate tau at Thr175. Further, downstream events known to follow Thr175 phosphorylation and known to be associated with pathological tau fibril formation (pSer9-GSK3ß and pThr231 tau induction) also remained unchanged. We conclude that while LRRK2 expression is altered in TBI, it does not contribute directly to pThr175 tau generation.

Patients with progression of spinal metastases who present to the clinic have better outcomes compared to those who present to the emergency department.

BACKGROUND: As cancer therapies have improved, spinal metastases are increasingly common. Resulting complications have a significant impact on patient's quality of life. Optimal methods of surveillance and avoidance of neurologic deficits are understudied. This study compares the clinical course of patients who initially presented to the emergency department (ED) versus a multidisciplinary spine oncology clinic and who underwent stereotactic body radiation therapy (SBRT) secondary to progression/presentation of metastatic spine disease. METHODS: We performed a retrospective analysis of a prospectively maintained database of adult oncologic patients who underwent spinal SBRT at a single hospital from 2010 to 2021. Descriptive statistics and survival analyses were performed. RESULTS: We identified 498 spinal radiographic treatment sites in 390 patients. Of these patients, 118 (30.3%) presented to the ED. Patients presenting to the ED compared to the clinic had significantly more severe spinal compression (52.5% vs. 11.7%; p < 0.0001), severe pain (28.8% vs. 10.3%; p < 0.0001), weakness (24.5% vs. 4.5%; p < 0.0001), and difficulty walking (24.5% vs. 4.5%; p < 0.0001). Patients who presented to the ED compared to the clinic were significantly more likely to have surgical intervention followed by SBRT (55.4% vs. 15.3%; p < 0.0001) compared to SBRT alone. Patients who presented to the ED compared to the clinic had a significantly quicker interval to distant spine progression (5.1 ± 6.5 vs. 9.1 ± 10.2 months; p = 0.004), systemic progression (5.1 ± 7.2 vs. 9.2 ± 10.7 months; p < 0.0001), and worse overall survival (9.3 ± 10.0 vs. 14.3 ± 13.7 months; p = 0.002). CONCLUSION: The establishment of multidisciplinary spine oncology clinics is an opportunity to potentially allow for earlier, more data-driven treatment of their spinal metastatic disease.

Local Control in Patients with Metastatic Renal Cell Carcinoma to the Spine: The Experience of an Institution with a Multidisciplinary Spine Oncology Program.

BACKGROUND: The outcomes for patients with metastatic renal cell carcinoma (RCC) to the spine who underwent stereotactic body radiotherapy (SBRT) through a multidisciplinary spine oncology program are not well described. We sought to describe the clinical course and local control rates at 1 and 2 years for these patients. METHODS: A retrospective analysis of a prospectively maintained database of adult oncologic patients receiving SBRT to the spine through a multidisciplinary spine oncology program at a single institution from 2010 to 2021 was performed. Patients with a pathologic diagnosis of RCC were included. RESULTS: A total of 75 spinal sites were treated in 60 patients. Of the 60 patients, 75.0% were men, and the mean patient age was 59.2 ± 11.3 years. At 1 year after treatment, 6 of the 60 patients were lost to follow-up. Of the remaining 54 patients, 18 were censored by death and 7 treatment sites showed local recurrence, for 37 of 44 treatment sites with local control (87.8%). At 2 years, 1 additional local recurrence had developed, 15 patients were censored by death, and no additional patients had been lost to follow-up, resulting in 28 of 36 treatment sites with local control (83.2%). None of the patients who had undergone repeat SBRT had local recurrence at 1 or 2 years. For those with local recurrence, the average time from treatment to progression was 6.6 ± 6.5 months. CONCLUSIONS: In this cohort, one of the largest reported studies of spine SBRT for metastatic RCC, local control was high at 1 and 2 years. Our findings support the role of coordinated, algorithmic treatment for these patients.

SARS-CoV-2, aging, and Post-COVID-19 neurodegeneration.

As the world continues to experience the effects of SARS-CoV-2, there is evidence to suggest that the sequelae of viral infection (the post-COVID-19 condition; PCC) at both an individual and population level will be significant and long-lasting. The history of pandemics or epidemics in the last 100 years caused by members of the RNA virus family, of which coronaviruses are a member, provides ample evidence of the acute neurological effects. However, except for the H1N1 influenza pandemic of 1918/1919 (the Spanish flu) with its associated encephalitis lethargica, there is little information on long-term neurological sequelae. COVID-19 is the first pandemic that has occurred in a setting of an aging population, especially in several high-income countries. Its survivors are at the greatest risk for developing neurodegenerative conditions as they age, rendering the current pandemic a unique paradigm not previously witnessed. The SARS-CoV-2 virus, among the largest of the RNA viruses, is a single-stranded RNA that encodes for 29 proteins that include the spike protein that contains the key domains required for ACE2 binding, and a complex array of nonstructural proteins (NSPs) and accessory proteins that ensure the escape of the virus from the innate immune response, allowing for its efficient replication, translation, and exocytosis as a fully functional virion. Increasingly, these proteins are also recognized as potentially contributing to biochemical and molecular processes underlying neurodegeneration. In addition to directly being taken up by brain endothelium, the virus or key protein constituents can be transported to neurons, astrocytes, and microglia by extracellular vesicles and can accelerate pathological fibril formation. The SARS-CoV-2 nucleocapsid protein is intrinsically disordered and can participate in liquid condensate formation, including as pathological heteropolymers with neurodegenerative disease-associated RNA-binding proteins such as TDP-43, FUS, and hnRNP1A. As the SARS-CoV-2 virus continues to mutate under the immune pressure exerted by highly efficacious vaccines, it is evolving into a virus with greater transmissibility but less severity compared with the original strain. The potential of its lingering impact on the nervous system thus has the potential to represent an ongoing legacy of an even greater global health challenge than acute infection.

Targeted Public Health Training for Neurosurgeons: An Essential Task for the Prioritization of Neurosurgery in the Evolving Global Health Landscape.

The gap between the tremendous burden of neurological disease requiring surgical management and the limited capacity for neurosurgical care has fueled the growth of the global neurosurgical movement. It is estimated that an additional 23 300 neurosurgeons are needed to meet the burden posed by essential cases across the globe. Initiatives to increase neurosurgical capacity through systems strengthening and workforce development are key elements in correcting this deficit. Building on the growing interest in global health among neurosurgical trainees, we propose the integration of targeted public health education into neurosurgical training, in both high-income countries and low- and middle-income countries. This effort will ensure that graduates possess the fundamental skillsets and experience necessary to participate in and lead capacity-building efforts in the developing countries. This additional public health training can also help neurosurgical residents to achieve the core competencies outlined by accreditation boards, such as the Accreditation Committee on Graduate Medical Education in the United States. In this narrative review, we describe the global burden of neurosurgical disease, establish the need and role for the global neurosurgeon, and discuss pathways for implementing targeted global public health education in the field of neurosurgery.

Navigated retrodiaphragmatic/retroperitoneal approach for the treatment of symptomatic kyphoscoliosis: an operative video.

Retropleural, retrodiaphragmatic, and retroperitoneal approaches are utilized to access difficult thoracolumbar junction (T10-L2) pathology. The authors present a 58-year-old man with chronic low-back pain who failed years of conservative therapy. Preoperative radiographs demonstrated significant levoconvex scoliosis with coronal and sagittal imbalance. He underwent a retrodiaphragmatic/retroperitoneal approach for T12-L1, L1-2, L2-3, and L3-4 interbody release and fusion in conjunction with second-stage facet osteotomies, L4-5 TLIF, and T10-iliac posterior instrumented fusion. This video focuses on the retrodiaphragmatic approach assisted by 3D navigation. The video can be found here: https://stream.cadmore.media/r10.3171/2022.3.FOCVID2215.

Finding Common Ground on the Site of Onset of Amyotrophic Lateral Sclerosis.

The fundamental origin of amyotrophic lateral sclerosis (ALS) has remained an enigma since its earliest description as a relentlessly progressive degeneration with prominent neuromuscular manifestations that are associated with upper and lower motor neuron dysfunction. While this remains the hallmark of ALS, a significant proportion of patients will also demonstrate one or more features of frontotemporal dysfunction, including a frontotemporal dementia (FTD). Understanding whether these two seemingly disparate syndromes are simply reflective of the co-occurrence of two distinct pathological processes or the clinical manifestations of a common pathophysiological derangement involving the brain more widely has gripped contemporary ALS researchers. Supporting a commonality of causation, both ALS and FTD show an alteration in the metabolism of TAR DNA-binding protein 43 (TDP-43), marked by a shift in nucleocytoplasmic localization alongside a broad range of neuronal cytoplasmic inclusions consisting of pathological aggregates of RNA binding proteins. Similarly, several disease-associated or disease-modifying genetic mutations that are shared between the two disorders suggests shared underlying mechanisms. In both, a prominent glial response has been postulated to contribute to non-cell autonomous spread. A more contemporary hypothesis however suggests that syndromes of cortical and subcortical dysfunction are driven by impairments in discrete neural networks. This postulates that such networks, including networks subserving motor or cognitive function, possess unique and selective vulnerabilities to either single molecular toxicities or combinations thereof. The co-occurrence of one or more network dysfunctions in ALS and in FTD is thus a reflection not of unique neuroanatomic correlates, but rather of shared molecular vulnerabilities. The basis of such shared vulnerabilities becomes the fulcrum around which the next advances in our understanding of ALS and its possible therapy will develop.

Syrinx regression after correction of iatrogenic kyphotic deformity: illustrative case.

BACKGROUND: Syringomyelia has a long-established association with pediatric scoliosis, but few data exist on the relationship of syringomyelia to pediatric kyphotic deformities. OBSERVATIONS: This report reviewed a unique case of rapid and sustained regression of syringomyelia in a 13-year-old girl after surgical correction of iatrogenic kyphotic deformity. LESSONS: In cases of syringomyelia associated with acquired spinal deformity, treatment of deformity to resolve an associated subarachnoid block should be considered because it may obviate the need for direct treatment of syrinx.