CT-guided vs. fluoroscopically guided transforaminal epidural steroid injections for lumbar radiculopathy: a comparison of efficacy, safety and cost.

INTRODUCTION: There are no formal guidelines for whether CT-guided or fluoroscopy-guided TFESI should be undertaken for patients with symptoms of lumbar nerve root irritation and corresponding nerve impingement. Here, we sought to compare the efficacy, safety and cost of computer tomography (CT)-guided and fluoroscopically guided transforaminal epidural steroid injection (TFESI). MATERIALS AND METHODS: All patients who underwent lumbar TFESI at our institution between June 2016 and June 2018 were identified. Six-week follow-up outcomes were categorised. The radiation doses and associated cost was retrieved from our institution's costing system. RESULTS: One hundred and sixteen patients were included (CT-50; fluoroscopy-56). There were no complications. More patients were discharged 6 weeks after CT-guided lumbar TFESI when compared with fluoroscopically guided TFESI (CT-23, fluoroscopy-14 (P = 0.027)). There was no difference in the number of patients who were referred to surgery (P = 0.18), for further pain management (P = 0.45), or for further TFESI (P = 0.43). The effective radiation dose was significantly higher for CT-guided TFESI (CT-5.73 mSv (3.87 to 7.76); fluoroscopy-0.55 mSv (0.11 to 1.4) (P < 0.01)). The total cost for CT-guided lumbar TFESI was £237.50 (£235 to £337), over £800 less than under fluoroscopic guidance (£1052 (£892.80 to £1298.00), P < 0.01)). Removing cost associated with staff and theatre use (staffing, theatre, medical indemnity and overheads) revealed CT-guided lumbar TFESI to be less expensive than if the procedure was fluoroscopy-guided-CT-guided: £132.6 (130.8 to 197.5); fluoroscopy: £237.4 (£209.2 to £271.9) (P = 0.019). CONCLUSIONS: CT-guided TFESI was associated with a higher discharge rate, a lower cost, but a ten times higher radiation dose when compared with fluoroscopically guided TFESI. Prospective studies are required to compare the efficacy of these procedures and to investigate how the radiation dose of CT-guided TFESI can be reduced without jeopardising efficacy or safety.

Molecular signatures of hemagglutinin stem-directed heterosubtypic human neutralizing antibodies against influenza A viruses.

Recent studies have shown high usage of the IGHV1-69 germline immunoglobulin gene for influenza hemagglutinin stem-directed broadly-neutralizing antibodies (HV1-69-sBnAbs). Here we show that a major structural solution for these HV1-69-sBnAbs is achieved through a critical triad comprising two CDR-H2 loop anchor residues (a hydrophobic residue at position 53 (Ile or Met) and Phe54), and CDR-H3-Tyr at positions 98±1; together with distinctive V-segment CDR amino acid substitutions that occur in positions sparse in AID/polymerase-η recognition motifs. A semi-synthetic IGHV1-69 phage-display library screen designed to investigate AID/polη restrictions resulted in the isolation of HV1-69-sBnAbs that featured a distinctive Ile52Ser mutation in the CDR-H2 loop, a universal CDR-H3 Tyr at position 98 or 99, and required as little as two additional substitutions for heterosubtypic neutralizing activity. The functional importance of the Ile52Ser mutation was confirmed by mutagenesis and by BCR studies. Structural modeling suggests that substitution of a small amino acid at position 52 (or 52a) facilitates the insertion of CDR-H2 Phe54 and CDR-H3-Tyr into adjacent pockets on the stem. These results support the concept that activation and expansion of a defined subset of IGHV1-69-encoded B cells to produce potent HV1-69-sBnAbs does not necessarily require a heavily diversified V-segment acquired through recycling/reentry into the germinal center; rather, the incorporation of distinctive amino acid substitutions by Phase 2 long-patch error-prone repair of AID-induced mutations or by random non-AID SHM events may be sufficient. We propose that these routes of B cell maturation should be further investigated and exploited as a pathway for HV1-69-sBnAb elicitation by vaccination.

Engineering of an all-heteronuclear 5-qubit NMR quantum computer.

The realization of an all-heteronuclear 5-qubit nuclear magnetic resonance quantum computer is reported, from the design and synthesis of a suitable molecule through the engineering of a prototype 6-channel probe head. Full control over the quantum computer is shown by a benchmark experiment.

Structure of the DNA deaminase domain of the HIV-1 restriction factor APOBEC3G.

The human APOBEC3G (apolipoprotein B messenger-RNA-editing enzyme, catalytic polypeptide-like 3G) protein is a single-strand DNA deaminase that inhibits the replication of human immunodeficiency virus-1 (HIV-1), other retroviruses and retrotransposons. APOBEC3G anti-viral activity is circumvented by most retroelements, such as through degradation by HIV-1 Vif. APOBEC3G is a member of a family of polynucleotide cytosine deaminases, several of which also target distinct physiological substrates. For instance, APOBEC1 edits APOB mRNA and AID deaminates antibody gene DNA. Although structures of other family members exist, none of these proteins has elicited polynucleotide cytosine deaminase or anti-viral activity. Here we report a solution structure of the human APOBEC3G catalytic domain. Five alpha-helices, including two that form the zinc-coordinating active site, are arranged over a hydrophobic platform consisting of five beta-strands. NMR DNA titration experiments, computational modelling, phylogenetic conservation and Escherichia coli-based activity assays combine to suggest a DNA-binding model in which a brim of positively charged residues positions the target cytosine for catalysis. The structure of the APOBEC3G catalytic domain will help us to understand functions of other family members and interactions that occur with pathogenic proteins such as HIV-1 Vif.

Optimization of van der Waals energy for protein side-chain placement and design.

Computational determination of optimal side-chain conformations in protein structures has been a long-standing and challenging problem. Solving this problem is important for many applications including homology modeling, protein docking, and for placing small molecule ligands on protein-binding sites. Programs available as of this writing are very fast and reasonably accurate, as measured by deviations of side-chain dihedral angles; however, often due to multiple atomic clashes, they produce structures with high positive energies. This is problematic in applications where the energy values are important, for example when placing small molecules in docking applications; the relatively small binding energy of the small molecule is drowned by the large energy due to atomic clashes that hampers finding the lowest energy state of the docked ligand. To address this we have developed an algorithm for generating a set of side-chain conformations that is dense enough that at least one of its members would have a root mean-square deviation of no more than R Å from any possible side-chain conformation of the amino acid. We call such a set a side-chain cover set of order R for the amino acid. The size of the set is constrained by the energy of the interaction of the side chain to the backbone atoms. Then, side-chain cover sets are used to optimize the conformation of the side chains given the coordinates of the backbone of a protein. The method we use is based on a variety of dead-end elimination methods and the recently discovered dynamic programming algorithm for this problem. This was implemented in a computer program called Octopus where we use side-chain cover sets with very small values for R, such as 0.1 Å, which ensures that for each amino-acid side chain the set contains a conformation with a root mean-square deviation of, at most, R from the optimal conformation. The side-chain dihedral-angle accuracy of the program is comparable to other implementations; however, it has the important advantage that the structures produced by the program have negative energies that are very close to the energies of the crystal structure for all tested proteins.

Restarting Elective Orthopaedic Surgery During the COVID-19 Pandemic: Lessons Learned.

Introduction  Coronavirus disease 2019 (COVID-19) resulted in postponing non-emergency elective surgeries beginning in April 2020. Our hospital successfully restarted elective orthopaedic surgery during the pandemic to help improve the quality of life of patients with chronic disabilities.  This study describes the development of local protocols and pathways to allow for a safe restart of elective orthopaedic surgery in a COVID-19-free 'green' site. It includes the morbidity and mortality outcomes of those patients who underwent non-emergency orthopaedic operations during this time.  Methods  This is a prospective cohort study over an eight-week period evaluating 104 patients undergoing non-emergency orthopaedic procedures through a COVID-19-free surgical pathway. The primary outcome measure was 14-day postoperative mortality. The main secondary outcome measures were the development of a COVID-19 infection in the hospital and 14 days postoperatively as well as the need for intensive care unit admissions.  Results  No patients developed a COVID-19 infection. There were no intensive care unit admissions or postoperative deaths during our study time frame. There was no statistical difference seen for age (< 70 or > 70), gender, body mass index, or American Society of Anesthesiologists (ASA) grades in the development of postoperative complications.  Conclusions  This study describes a roadmap to setting up a protocolised elective operating service for orthopaedic surgery. It has shown that standardised protocols in a COVID-19-free 'green' site, preoperative COVID-19 testing, and adherence to national guidelines on self-isolation can help prevent developing COVID-19 infection postoperatively and reduce the risk of postoperative mortality.

The alphabeta T cell receptor is an anisotropic mechanosensor.

Thymus-derived lymphocytes protect mammalian hosts against virus- or cancer-related cellular alterations through immune surveillance, eliminating diseased cells. In this process, T cell receptors (TCRs) mediate both recognition and T cell activation via their dimeric alphabeta, CD3 epsilon gamma, CD3 epsilon delta, and CD3 zeta zeta subunits using an unknown structural mechanism. Here, site-specific binding topology of anti-CD3 monoclonal antibodies (mAbs) and dynamic TCR quaternary change provide key clues. Agonist mAbs footprint to the membrane distal CD3 epsilon lobe that they approach diagonally, adjacent to the lever-like C beta FG loop that facilitates antigen (pMHC)-triggered activation. In contrast, a non-agonist mAb binds to the cleft between CD3 epsilon and CD3 gamma in a perpendicular mode and is stimulatory only subsequent to an external tangential but not a normal force ( approximately 50 piconewtons) applied via optical tweezers. Specific pMHC but not irrelevant pMHC activates a T cell upon application of a similar force. These findings suggest that the TCR is an anisotropic mechanosensor, converting mechanical energy into a biochemical signal upon specific pMHC ligation during immune surveillance. Activating anti-CD3 mAbs mimic this force via their intrinsic binding mode. A common TCR quaternary change rather than conformational alterations can better facilitate structural signal initiation, given the vast array of TCRs and their specific pMHC ligands.

The solution structure of type III effector protein AvrPto reveals conformational and dynamic features important for plant pathogenesis.

Pseudomonas syringae pv. tomato, the causative agent of bacterial speck disease of tomato, uses a type III secretion system (TTSS) to deliver effector proteins into the host cell. In resistant plants, the bacterial effector protein AvrPto physically interacts with the host Pto kinase and elicits antibacterial defense responses. In susceptible plants, which lack the Pto kinase, AvrPto acts as a virulence factor to promote bacterial growth. The solution structure of AvrPto reveals a functional core consisting of a three-helix bundle motif flanked by disordered N- and C-terminal tails. Residues required for Pto binding lie in a 19 residue Omega loop. Modeling suggests a hydrophobic patch involving the activation loop of Pto forms a contact surface with the AvrPto Omega loop and that helix packing mediates interactions between AvrPto and putative virulence targets Api2 and Api3. The AvrPto structure has a low stability that may facilitate chaperone-independent secretion by the TTSS.

Long-term clinical and radiological outcomes of Copenhagen syndrome with 19 affected levels: a case report.

BACKGROUND CONTEXT: Copenhagen syndrome, or progressive noninfectious anterior vertebral fusion, is a rare disorder of unknown etiology that usually presents with thoracolumbar kyphosis in childhood. There have been no long-term reports on outcome in children with multiple affected levels with longitudinal imaging from infancy to adulthood. PURPOSE: The purpose of this study was to report the long-term outcome of nonoperative management of a child with Copenhagen syndrome affecting 19 vertebral levels. STUDY DESIGN: This study is a case report. METHODS: The study included longitudinal clinical and radiological follow-ups. RESULTS: A 1-year-old female presented with thoracolumbar kyphosis. Plain radiographs and magnetic resonance imaging demonstrated kyphosis associated with anterior disc space narrowing plus T11-T12 and L2-L3 vertebral end-plate abnormalities. Initial treatment with a plaster jacket followed by brace failed to prevent progressive vertebral involvement and kyphosis during childhood. At skeletal maturity, no further levels became involved, and progression was halted. In total, 19 levels showed anterior fusion. CONCLUSIONS: This case describes the long-term outcome of nonoperative management for progressive noninfectious anterior vertebral fusion affecting multiple levels. Extensive vertebral involvement does not always require surgical intervention. There is a need for future research on the prognostic indicators for progression and long-term outcome.

Combined Type II Odontoid Fracture With Axis Anterior Arch Fracture: A Case Report in an Elderly Patient.

Associated fractures of the atlas and axis are frequent, particularly in the elderly patients following a simple low-energy fall. This injury can be easily misdiagnosed on initial plain radiographs, and therefore computed tomography scan is a useful adjunct in patients with a degenerative spine. There is still no consensus as to the optimal treatment of combined axis-atlas fractures, and the majority of authors propose a therapeutic strategy dependent on the odontoid fracture pattern. We describe a combined atlas and axis fracture in a 92-year-old patient who was managed with nonoperative treatment in a rigid collar. The association of C1 anterior arch with a C2 type II odontoid fracture is a rare combination, which to our knowledge has never been reported following nonoperative treatment. There was a good functional outcome at 1-year follow-up with the fracture progressing to a fibrous nonunion of the odontoid process.

Conformational dynamics of the Rpt6 ATPase in proteasome assembly and Rpn14 binding.

Juxtaposed to either or both ends of the proteasome core particle (CP) can exist a 19S regulatory particle (RP) that recognizes and prepares ubiquitinated proteins for proteolysis. RP triphosphatase proteins (Rpt1-Rpt6), which are critical for substrate translocation into the CP, bind chaperone-like proteins (Hsm3, Nas2, Nas6, and Rpn14) implicated in RP assembly. We used NMR and other biophysical methods to reveal that S. cerevisiae Rpt6's C-terminal domain undergoes dynamic helix-coil transitions enabled by helix-destabilizing glycines within its two most C-terminal α helices. Rpn14 binds selectively to Rpt6's four-helix bundle, with surprisingly high affinity. Loss of Rpt6's partially unfolded state by glycine substitution (Rpt6 G³6°,³87A) disrupts holoenzyme formation in vitro, an effect enhanced by Rpn14. S. cerevisiae lacking Rpn14 and incorporating Rpt6 G³6°,³87A demonstrate hallmarks of defective proteasome assembly and synthetic growth defects. Rpt4 and Rpt5 exhibit similar exchange, suggesting that conserved structural heterogeneity among Rpt proteins may facilitate RP-CP assembly.

Control aspects of quantum computing using pure and mixed states.

Steering quantum dynamics such that the target states solve classically hard problems is paramount to quantum simulation and computation. And beyond, quantum control is also essential to pave the way to quantum technologies. Here, important control techniques are reviewed and presented in a unified frame covering quantum computational gate synthesis and spectroscopic state transfer alike. We emphasize that it does not matter whether the quantum states of interest are pure or not. While pure states underly the design of quantum circuits, ensemble mixtures of quantum states can be exploited in a more recent class of algorithms: it is illustrated by characterizing the Jones polynomial in order to distinguish between different (classes of) knots. Further applications include Josephson elements, cavity grids, ion traps and nitrogen vacancy centres in scenarios of closed as well as open quantum systems.

The C-terminal domain of eukaryotic initiation factor 5 promotes start codon recognition by its dynamic interplay with eIF1 and eIF2ß.

Recognition of the proper start codon on mRNAs is essential for protein synthesis, which requires scanning and involves eukaryotic initiation factors (eIFs) eIF1, eIF1A, eIF2, and eIF5. The carboxyl terminal domain (CTD) of eIF5 stimulates 43S preinitiation complex (PIC) assembly; however, its precise role in scanning and start codon selection has remained unknown. Using nuclear magnetic resonance (NMR) spectroscopy, we identified the binding sites of eIF1 and eIF2ß on eIF5-CTD and found that they partially overlapped. Mutating select eIF5 residues in the common interface specifically disrupts interaction with both factors. Genetic and biochemical evidence indicates that these eIF5-CTD mutations impair start codon recognition and impede eIF1 release from the PIC by abrogating eIF5-CTD binding to eIF2ß. This study provides mechanistic insight into the role of eIF5-CTD's dynamic interplay with eIF1 and eIF2ß in switching PICs from an open to a closed state at start codons.

Acromial impression fracture of the greater tuberosity with massive rotator cuff tear: this need not be a nightmare!

An avulsion fracture of the greater tuberosity of the humerus with associated rotator cuff tear is rare. The authors describe the unusual case of a shoulder injury with an isolated, displaced greater tuberosity fracture associated with a massive rotator cuff tear. Due to the rotator cuff dysfunction, this patient presented with significant functional loss.

Antibody mechanics on a membrane-bound HIV segment essential for GP41-targeted viral neutralization.

Broadly neutralizing antibodies such as 2F5 are directed against the membrane-proximal external region (MPER) of HIV-1 GP41 and recognize well-defined linear core sequences. These epitopes can be engrafted onto protein scaffolds to serve as immunogens with high structural fidelity. Although antibodies that bind to this core GP41 epitope can be elicited, they lack neutralizing activity. To understand this paradox, we used biophysical methods to investigate the binding of human 2F5 to the MPER in a membrane environment, where it resides in vivo. Recognition is stepwise, through a paratope more extensive than core binding site contacts alone, and dynamic rearrangement through an apparent scoop-like movement of heavy chain complementarity-determining region 3 (CDRH3) is essential for MPER extraction from the viral membrane. Core-epitope recognition on the virus requires the induction of conformational changes in both the MPER and the paratope. Hence, target neutralization through this lipid-embedded viral segment places stringent requirements on the plasticity of the antibody combining site.

Nuclear-magnetic-resonance quantum calculations of the Jones polynomial.

The repertoire of problems theoretically solvable by a quantum computer recently expanded to include the approximate evaluation of knot invariants, specifically the Jones polynomial. The experimental implementation of this evaluation, however, involves many known experimental challenges. Here we present experimental results for small-scale approximate evaluation of the Jones polynomial by nuclear magnetic resonance (NMR); in addition, we show how to escape from the limitations of NMR approaches that employ pseudopure states. Specifically, we use two spin-1/2 nuclei of natural abundance chloroform and apply a sequence of unitary transforms representing the trefoil knot, the figure-eight knot, and the Borromean rings. After measuring the nuclear spin state of the molecule in each case, we are able to estimate the value of the Jones polynomial for each of the knots.

Eukaryotic initiation factor (eIF) 1 carries two distinct eIF5-binding faces important for multifactor assembly and AUG selection.

Eukaryotic initiation factor (eIF) 1 is a small protein (12 kDa) governing fidelity in translation initiation. It is recruited to the 40 S subunit in a multifactor complex with Met-tRNA(i)(Met), eIF2, eIF3, and eIF5 and binds near the P-site. eIF1 release in response to start codon recognition is an important signal to produce an 80 S initiation complex. Although the ribosome-binding face of eIF1 was identified, interfaces to other preinitiation complex components and their relevance to eIF1 function have not been determined. Exploiting the solution structure of yeast eIF1, here we locate the binding site for eIF5 in its N-terminal tail and at a basic/hydrophobic surface area termed KH, distinct from the ribosome-binding face. Genetic and biochemical studies indicate that the eIF1 N-terminal tail plays a stimulatory role in cooperative multifactor assembly. A mutation altering the basic part of eIF1-KH is lethal and shows a dominant phenotype indicating relaxed start codon selection. Cheung et al. recently demonstrated that the alteration of hydrophobic residues of eIF1 disrupts a critical link to the preinitiation complex that suppresses eIF1 release before start codon selection (Cheung, Y.-N., Maag, D., Mitchell, S. F., Fekete, C. A., Algire, M. A., Takacs, J. E., Shirokikh, N., Pestova, T., Lorsch, J. R., and Hinnebusch, A. (2007) Genes Dev. 21, 1217-1230 ). Interestingly, eIF1-KH includes the altered hydrophobic residues. Thus, eIF5 is an excellent candidate for the direct partner of eIF1-KH that mediates the critical link. The direct interaction at eIF1-KH also places eIF5 near the decoding site of the 40 S subunit.

Fatal fat embolism complicating cemented total knee replacement: another manifestation of the metabolic syndrome?

We report the case of a 52-year-old man who died of massive fat emboli 39 h after undergoing elective total knee replacement. His past medical history included hypertension, obesity and diabetes (most of the clusters of the metabolic syndrome). Post-mortem pathological examination showed fat embolism in the kidneys and the brain. This is the first reported case of fat emboli as the cause of death in an association with metabolic syndrome, and the case suggests that the fat embolism should be anticipated in over weight and obese individuals with three or more of the risk factors of the metabolic syndrome.

Small-molecule inhibition of the interaction between the translation initiation factors eIF4E and eIF4G.

Assembly of the eIF4E/eIF4G complex has a central role in the regulation of gene expression at the level of translation initiation. This complex is regulated by the 4E-BPs, which compete with eIF4G for binding to eIF4E and which have tumor-suppressor activity. To pharmacologically mimic 4E-BP function we developed a high-throughput screening assay for identifying small-molecule inhibitors of the eIF4E/eIF4G interaction. The most potent compound identified, 4EGI-1, binds eIF4E, disrupts eIF4E/eIF4G association, and inhibits cap-dependent translation but not initiation factor-independent translation. While 4EGI-1 displaces eIF4G from eIF4E, it effectively enhances 4E-BP1 association both in vitro and in cells. 4EGI-1 inhibits cellular expression of oncogenic proteins encoded by weak mRNAs, exhibits activity against multiple cancer cell lines, and appears to have a preferential effect on transformed versus nontransformed cells. The identification of this compound provides a new tool for studying translational control and establishes a possible new strategy for cancer therapy.

TreeDock: a tool for protein docking based on minimizing van der Waals energies.

Predicting protein-protein and protein-ligand docking remains one of the challenging topics of structural biology. The main problems are (i) to reliably estimate the binding free energies of docked states, (ii) to enumerate possible docking orientations at a high resolution, and (iii) to consider mobility of the docking surfaces and structural rearrangements upon interaction. Here we present a novel algorithm, TreeDock, that addresses the enumeration problem in a rigid-body docking search. By representing molecules as multidimensional binary search trees and by exploring a sufficient number of docking orientations such that two chosen atoms, one from each molecule, are always in contact, TreeDock is able to explore all clash-free orientations at very fine resolution in a reasonable amount of time. Due to the speed of the program, many contact pairs can be examined to search partial or complete surface areas. The deterministic systematic search of TreeDock is in contrast to most other docking programs that use stochastic searches such as Monte Carlo or simulated annealing methods. At this point, we have used the Lennard-Jones potential as the only scoring function and show that this can predict the correct docked conformation for a number of protein-protein and protein-ligand complexes. The program is most powerful if some information is known about the location of binding faces from NMR chemical-shift perturbation studies, orientation information from residual dipolar coupling, or mutational screening. The approach has the potential to include docking-site mobility by performing molecular dynamics or other randomization methods of the docking site and docking families to families of structures. The performance of the algorithm is demonstrated by docking three complexes of immunoglobulin superfamily domains, CD2 to CD58, the V(alpha) domain of a T-cell receptor to its V(beta) domain, and a T-cell receptor to a pMHC complex as well as a small molecule inhibitor to a phosphatase.