Identification of essential sites of lipid peroxidation in ferroptosis.

Ferroptosis, an iron-dependent form of cell death driven by lipid peroxidation, provides a potential treatment avenue for drug-resistant cancers and may play a role in the pathology of some degenerative diseases. Identifying the subcellular membranes essential for ferroptosis and the sequence of their peroxidation will illuminate drug discovery strategies and ferroptosis-relevant disease mechanisms. In this study, we employed fluorescence and stimulated Raman scattering imaging to examine the structure-activity-distribution relationship of ferroptosis-modulating compounds. We found that, although lipid peroxidation in various subcellular membranes can induce ferroptosis, the endoplasmic reticulum (ER) membrane is a key site of lipid peroxidation. Our results suggest an ordered progression model of membrane peroxidation during ferroptosis that accumulates initially in the ER membrane and later in the plasma membrane. Thus, the design of ER-targeted inhibitors and inducers of ferroptosis may be used to optimally control the dynamics of lipid peroxidation in cells undergoing ferroptosis.

Aseptic Revision Total Hip Arthroplasty Through an Anterior Approach: Survivorship and Risk Factors for Re-Revision.

BACKGROUND: The utilization of anterior-based approaches for total hip arthroplasty (THA) is increasing. Literature on the outcomes of revision THA (rTHA) through an anterior approach, however, is sparse. This study reports the survivorship and risk factors for re-revision in patients undergoing aseptic rTHA through an anterior approach. METHODS: This was a single-institution, retrospective cohort analysis of patients who underwent aseptic rTHA through an anterior approach (direct anterior, anterior-based muscle sparing) from January 2017 to December 2021, regardless of the original surgical approach. Exclusion criteria were age <18 years, conversion THA, and septic revisions. Patient demographics, complications, and postoperative outcomes were collected. Kaplan-Meier curves were used to measure survivorship while Cox regression analyses were used to identify risk factors for re-revision of THA. RESULTS: We identified 251 total anterior rTHAs, of which 155 were aseptic anterior revisions. There were 111 patients (111 rTHAs; 63 anterior-based muscle sparing and 48 direct anterior) who met criteria and had a mean follow-up of 4.2 years (range, 2.1 to 6.9). There were a total of 54 (49%) anterior-based index approaches and 57 (51%) posterior index approaches. The most common indications for rTHA were femoral loosening (n = 25, 22.5%), followed by instability (n = 16, 14.4%) and wear or osteolysis (n = 16, 14.4%). At 2 years, the survivorship from reoperation and re-revision was 89% (95% confidence interval: 84 to 95) and 91% (95% confidence interval: 86 to 96), respectively. Reoperation occurred in 14 patients (12.6%) at a mean time of 7.8 months (range, 0.5 to 28.6). Re-revision occurred in 12 patients (10.8%) at a mean time of 7.3 months (range, 0.5 to 28.6). Instability was the most common reason for re-revision (4.5%). Neither index approach type, revision approach type, nor any patient-specific risk factors were identified as predictors of re-revision or reoperation in multivariable regression analysis. CONCLUSIONS: This study demonstrates an acceptable rate of re-revision when aseptic rTHA is performed through an anterior approach, with the most common reason for aseptic re-revision being instability.

Affinity maturation of a portable Fab-RNA module for chaperone-assisted RNA crystallography.

Antibody fragments such as Fabs possess properties that can enhance protein and RNA crystallization and therefore can facilitate macromolecular structure determination. In particular, Fab BL3-6 binds to an AAACA RNA pentaloop closed by a GC pair with ∼100 nM affinity. The Fab and hairpin have served as a portable module for RNA crystallization. The potential for general application make it desirable to adjust the properties of this crystallization module in a manner that facilitates its use for RNA structure determination, such as ease of purification, surface entropy or binding affinity. In this work, we used both in vitro RNA selection and phage display selection to alter the epitope and paratope sides of the binding interface, respectively, for improved binding affinity. We identified a 5'-GNGACCC-3' consensus motif in the RNA and S97N mutation in complimentarity determining region L3 of the Fab that independently impart about an order of magnitude improvement in affinity, resulting from new hydrogen bonding interactions. Using a model RNA, these modifications facilitated crystallization under a wider range of conditions and improved diffraction. The improved features of the Fab-RNA module may facilitate its use as an affinity tag for RNA purification and imaging and as a chaperone for RNA crystallography.

K-RasG12D Has a Potential Allosteric Small Molecule Binding Site.

KRAS is the most commonly mutated oncogene in human cancer, with particularly high mutation frequencies in pancreatic cancers, colorectal cancers, and lung cancers [Ostrem, J. M., and Shokat, K. M. (2016) Nat. Rev. Drug Discovery 15, 771-785]. The high prevalence of KRAS mutations and its essential role in many cancers make it a potentially attractive drug target; however, it has been difficult to create small molecule inhibitors of mutant K-Ras proteins. Here, we identified a putative small molecule binding site on K-RasG12D using computational analyses of the protein structure and then used a combination of computational and biochemical approaches to discover small molecules that may bind to this pocket, which we have termed the P110 site, due to its adjacency to proline 110. We confirmed that one compound, named K-Ras allosteric ligand KAL-21404358, bound to K-RasG12D, as measured by microscale thermophoresis, a thermal shift assay, and nuclear magnetic resonance spectroscopy. KAL-21404358 did not bind to four mutants in the P110 site, supporting our hypothesis that KAL-21404358 binds to the P110 site of K-RasG12D. This compound impaired the interaction of K-RasG12D with B-Raf and disrupted the RAF-MEK-ERK and PI3K-AKT signaling pathways. We synthesized additional compounds, based on the KAL-21404358 scaffold with more potent binding and greater aqueous solubility. In summary, these findings suggest that the P110 site is a potential site for binding of small molecule allosteric inhibitors of K-RasG12D.

Use of The Risk Assessment and Prediction Tool to Predict Same-day Discharge After Primary Hip and Knee Arthroplasty.

INTRODUCTION: The Risk Assessment and Prediction Tool (RAPT) is a preoperative screening tool developed to predict discharge disposition after total hip arthroplasty (THA) and total knee arthroplasty (TKA), but its predictive value for same-day discharge (SDD) has not been investigated. The aims of this study were (1) to assess RAPT's ability to predict SDD after primary THA and TKA and (2) to determine a cutoff RAPT score that may recognize patients appropriate for SDD. METHODS: Data were retrospectively collected from patients undergoing primary THA and TKA at a single tertiary care center between February 2020 and May 2021. A receiver operating characteristic curve was generated to choose a cutoff value to screen for SDD. Logistic regression analysis was done to identify factors including age, BMI, or RAPT score that may be associated with SDD. RESULTS: Three hundred sixty-one patients with preoperative RAPT scores were included in the analysis of whom 147 (42.6%) underwent SDD. A cutoff of ≥9 was identified for TKA and ≥11 for THA. RAPT had a predictive accuracy of only 66.7% for SDD, whereas the discharge plan documented in the preoperative note was 91.7% accurate. DISCUSSION: Although there is a positive association between RAPT and SDD, it is not a useful screening tool given its low predictive accuracy.

Robot-navigated pedicle screw insertion can reduce intraoperative blood loss and length of hospital stay: analysis of 1,633 patients utilizing propensity score matching.

BACKGROUND CONTEXT: Navigation and robotic technologies have emerged as an alternative option to conventional freehand techniques for pedicle screw insertion. However, the effectiveness of these technologies in reducing the perioperative complications of spinal fusion surgery remains limited due to the small cohort size in the existing literature. PURPOSE: To investigate whether utilization of robotically navigated pedicle screw insertion can reduce the perioperative complications of spinal fusion surgery-including reoperations-with a sizeable cohort. STUDY DESIGN: Retrospective study. PATIENT SAMPLE: Patients who underwent primary lumbar fusion surgery between 2019 and 2022. OUTCOME MEASURES: Perioperative complications including readmission, reoperation, its reasons, estimated blood loss, operative time, and length of hospital stay. METHODS: Patients' data were collected including age, sex, race, body mass index, upper-instrumented vertebra, lower-instrumented vertebra, number of screws inserted, and primary procedure name. Patients were classified into the following two groups: freehand group and robot group. The variable-ratio greedy matching was utilized to create the matched cohorts by propensity score and compared the outcomes between the two group. RESULTS: A total of 1,633 patients who underwent primary instrumented spinal lumbar fusion surgery were initially identified (freehand 1,286; robot 347). After variable ratio matching was performed with age, sex, body mass index, fused levels, and upper instrumented vertebrae level, 694 patients in the freehand group and 347 patients in robot groups were selected. The robot group showed less estimated blood loss (418.9±398.9 vs 199.2±239.6 ml; p<.001), shorter LOS (4.1±3.1 vs 3.2±3.0 days; p<.001) and similar operative time (212.5 vs 222.0 minutes; p=.151). Otherwise, there was no significant difference in readmission rate (3.6% vs 2.6%; p=.498), reoperation rate (3.2% vs 2.6%; p=.498), and screw malposition requiring reoperation (five cases, 0.7% vs one case, 0.3%; p=1.000). CONCLUSIONS: Perioperative complications requiring readmission and reoperation were similar between fluoroscopy guided freehand and robotic surgery. Robot-guided pedicle screw insertion can enhance surgical efficiency by reducing intraoperative blood loss and length of hospital stay without extending operative time.

Impact of Lumbar Disk Herniation on Performance Outcomes and New Contracts in the National Football League.

STUDY DESIGN: This was a retrospective cohort study. OBJECTIVE: To determine performance outcomes and the contract-signing ability for the most recent cohort of professional football players treated for lumbar disk herniation (LDH). SUMMARY OF BACKGROUND DATA: LDH can have a significant impact on the career of a National Football League (NFL) player. Previous studies have found favorable return to play (RTP) and performance outcomes for players with LDH, but the impact on the ability to sign new contracts (an important surrogate to assess continued success) has not previously been studied. MATERIALS AND METHODS: NFL players treated for LDH from 2000 to 2020 were identified from a public records search. Age, position, type of treatment, and RTP measures were collected. Pro Football Focus (PFF) performance grade and contract values were compared before the injury and after treatment. Multivariable logistic regression was used to identify independent risk factors associated with the ability to RTP and sign high-value contracts. RESULTS: One hundred one players were treated for an LDH, of which 75 returned to play. Posttreatment performance as measured by PFF was similar to preinjury levels ( P =0.2). However, both total and guaranteed contract values were significantly reduced ( P <0.01). In multivariable analysis, both lower age and higher preinjury PFF grade were independent predictors of RTP and ability to sign a new contract. A preinjury contract that contained a high proportion of guaranteed money was found to be an independent predictor of the ability to sign a contract that was >20% guaranteed. CONCLUSION: Although the majority of players were able to RTP at preserved performance levels following LDH treatment, their contract values were significantly reduced. RTP and contract-signing ability were not associated with the type of treatment, but rather baseline factors such as the player's age, performance, and preinjury compensation. LEVEL OF EVIDENCE: Level IV.

Surface Navigation and the Influence of Navigation on MIS Surgery.

STUDY DESIGN: Literature review. OBJECTIVES: To review the evidence for surface-based navigation in minimally-invasive spine surgery (MIS), provide an outline for its workflow, and present a wide range of MIS case examples in which surface-based navigation may be advantageous. METHODS: A comprehensive review of the literature and compilation of findings related to surface-based navigation in MIS was performed. Workflow and case examples utilizing surface-based navigation were described. RESULTS: The nascent literature regarding surface-based intraoperative navigation (ION) in spine surgery is encouraging and initial studies have shown that surface-based navigation can allow for accurate pedicle screw placement and decreased operative time, fluoroscopy time, and radiation exposure when compared to traditional fluoroscopic imaging. Surface-based navigation may be particularly useful in MIS cervical and lumbar decompressions and MIS lumbar instrumentation cases. CONCLUSIONS: Overall, it is possible that surface-based ION will become a mainstay in the armamentarium of enabling technologies utilized by minimally-invasive spine surgeons, but further studies are needed assessing its accuracy, complications, and cost-effectiveness.

Association between muscle health and patient-reported outcomes after lumbar microdiscectomy: early results.

BACKGROUND CONTEXT: Poor muscle health has been implicated as a source of back pain among patients with lumbar spine pathology. Recently, a novel magnetic resonance imaging (MRI)-based lumbar muscle health grade was shown to correlate with health-related quality of life scores. However, the impact of muscle health on postoperative functional outcomes following spine surgery remains to be investigated. PURPOSE: To determine whether muscle health grade measured by preoperative psoas and paralumbar muscle cross-sectional areas impact the achievement of minimal clinically important difference (MCID) following lumbar microdiscectomy. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: Consecutive patients who underwent 1-level lumbar microdiscectomy in a single institution between 2017 and 2021. OUTCOME MEASURES: Rate of MCID achievement, time to MCID achievement, PROMs including Oswestry Disability Index (ODI), visual analog scale for back pain (VAS back), VAS leg, Short Form 12 Physical Component Summary (SF-12 PCS), SF-12 Mental Component Summary (SF-12 MCS), and Patient Reported Outcomes Measurement Information System Physical Function (PROMIS PF). METHODS: Two previously validated methods for muscle health grading were applied. Axial T2 MRI were analyzed for muscle measurements. The psoas-based method utilized the normalized total psoas area (NTPA), which is the psoas cross-sectional area divided by the square of patient height (mm2/m2). Patients were divided into low and high NTPA groups based on sex-specific lowest quartile NTPA thresholds. The paralumbar-based method incorporated the paralumbar cross-sectional area normalized by body mass index (PL-CSA/BMI) and Goutallier classification. Score of 1 was added for either PL-CSA/BMI >130 or Goutallier class of ≤2. "Good" muscle health was defined as score of 2, and "poor" muscle health was defined as score of 0 to 1. Prospectively collected PROMs were analyzed at 2-week, 6-week, 3-month, 6-month, 1-year, and 2-year postoperative timepoints. The rate of and time to MCID achievement were compared among the cohorts. Bivariate analyses were performed to assess for correlations between psoas/paralumbar cross-sectional areas and change in PROM scores from baseline. RESULTS: The total cohort included 163 patients with minimum follow-up of 6 months and mean follow-up of 16.5 months. 40 patients (24.5%) were categorized into the low NTPA group, and 55 patients (33.7%) were categorized into the poor paralumbar muscle group. Low NTPA was associated with older age, lower BMI, and greater frequencies of Charlson Comorbidity Index (CCI) ≥1. Poor paralumbar muscle health was associated with older age, female sex, higher BMI, and CCI ≥1. There were no differences in rates of MCID achievement for any PROMs between low versus high NTPA groups or between poor versus good paralumbar groups. Low NTPA was associated with longer time to MCID achievement for ODI, VAS back, VAS leg, and SF-12 MCS. Poor paralumbar muscle health was associated with longer time to MCID achievement for VAS back, VAS leg, and SF-12 PCS. NTPA negatively correlated with change in VAS back (6-week, 12-week) and VAS leg (6-month). PL-CSA/BMI positively correlated with change in PROMIS-PF at 3 months follow-up. CONCLUSIONS: Among patients undergoing lumbar microdiscectomy, patients with worse muscle health grades achieved MCID at similar rates but required longer time to achieve MCID. Lower NTPA was weakly correlated with larger improvements in pain scores. PL-CSA/BMI positively correlated with change in PROMIS-PF. Our findings suggest that with regards to functional outcomes, patients with worse muscle health may take longer to recuperate postoperatively compared to those with better muscle health.

Robotics Reduces Radiation Exposure in Minimally Invasive Lumbar Fusion Compared With Navigation.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To compare robotics and navigation for minimally invasive elective lumbar fusion in terms of radiation exposure and time demand. SUMMARY OF BACKGROUND DATA: Although various studies have been conducted to demonstrate the benefits of both navigation and robotics over fluoroscopy in terms of radiation exposure, literature is lacking in studies comparing robotics versus navigation. MATERIALS AND METHODS: Patients who underwent elective one-level or two-level minimally invasive transforaminal lumbar interbody fusion (TLIF) by a single surgeon using navigation (Stryker SpineMask) or robotics (ExcelsiusGPS) were included (navigation 2017-2019, robotics 2019-2021, resulting in prospective cohorts of consecutive patients for each modality). All surgeries had the intraoperative computed tomography workflow. The two cohorts were compared for radiation exposure [fluoroscopy time and radiation dose: image capture, surgical procedure, and overall) and time demand (time for setup and image capture, operative time, and total operating room (OR) time]. RESULTS: A total of 244 patients (robotics 111, navigation 133) were included. The two cohorts were similar in terms of baseline demographics, primary/revision surgeries, and fusion levels. For one-level TLIF, total fluoroscopy time, total radiation dose, and % of radiation for surgical procedure were significantly less with robotics compared with navigation (20 vs. 25 s, P <0.001; 38 vs. 42 mGy, P =0.05; 58% vs. 65%, P =0.021). Although time for setup and image capture was significantly less with robotics (22 vs. 25 min, P <0.001) and operative time was significantly greater with robotics (103 vs. 93 min, P <0.001), there was no significant difference in the total OR time (145 vs. 141 min, P =0.25). Similar findings were seen for two-level TLIF as well. CONCLUSION: Robotics for minimally invasive TLIF, compared with navigation, leads to a significant reduction in radiation exposure both to the surgeon and patient, with no significant difference in the total OR time.