Polarization of the endoplasmic reticulum by ER-septin tethering.

Polarization of the plasma membrane (PM) into domains is an important mechanism to compartmentalize cellular activities and to establish cell polarity. Polarization requires formation of diffusion barriers that prevent mixing of proteins between domains. Recent studies have uncovered that the endoplasmic reticulum (ER) of budding yeast and neurons is polarized by diffusion barriers, which in neurons controls glutamate signaling in dendritic spines. The molecular identity of these barriers is currently unknown. Here, we show that a direct interaction between the ER protein Scs2 and the septin Shs1 creates the ER diffusion barrier in yeast. Barrier formation requires Epo1, a novel ER-associated subunit of the polarisome that interacts with Scs2 and Shs1. ER-septin tethering polarizes the ER into separate mother and bud domains, one function of which is to position the spindle in the mother until M phase by confining the spindle capture protein Num1 to the mother ER.

Combination of CD8ß Depletion and Interleukin-15 Superagonist N-803 Induces Virus Reactivation in Simian-Human Immunodeficiency Virus-Infected, Long-Term ART-Treated Rhesus Macaques.

The "shock and kill" strategy predicates that virus reactivation in latently infected cells is required to eliminate the human immunodeficiency virus (HIV) reservoir. In a recent study, we showed robust and persistent induction of plasma viremia in antiretroviral therapy (ART)-treated simian immunodeficiency virus-infected rhesus macaques (RMs) undergoing CD8α depletion and treated with the interleukin-15 (IL-15) superagonist N-803 (J. B. McBrien et al., Nature 578:154-159, 2020, https://doi.org/10.1038/s41586-020-1946-0). Of note, in that study we used an antibody targeting CD8α, thereby depleting NK cells, NKT cells, and γδ T cells, in addition to CD8+ T cells. In the current proof-of-concept study, we tested whether virus reactivation can be induced by administration of N-803 to simian-human chimeric immunodeficiency virus-infected, ART-treated RMs that are selectively depleted of CD8+ T cells via the CD8ß-targeting antibody CD8b255R1. CD8ß depletion was performed in five SHIVSF162P3-infected RMs treated with ART for 12 months and with plasma viremia consistently below 3 copies/ml. All animals received four weekly doses of N-803 starting at the time of CD8b255R1 administration. The induction of detectable plasma viremia was observed in three out of five RMs, with the level of virus reactivation seemingly correlated with the frequency of CD8+ T cells following CD8ß depletion as well as the level of virus reactivation observed when the same animals underwent CD8α depletion and N-803 administration after 24 weeks of ART. These data indicate that CD8ß depletion and N-803 administration can induce virus reactivation in SHIVSF162P3-infected RMs despite suboptimal depletion of CD8+ T cells and profound ART-induced suppression of virus replication, confirming a critical role for these cells in suppressing virus production and/or reactivation in vivo under ART.IMPORTANCE The "shock and kill" HIV cure strategy attempts to reverse and eliminate the latent viral infection that prevents eradication of the virus. Latency-reversing agents tested in clinical trials to date have failed to affect the HIV viral reservoir. IL-15 superagonist N-803, currently involved in a clinical trial for HIV cure, was recently shown by our laboratory to induce robust and persistent induction of plasma viremia during ART in three in vivo animal models of HIV infection. These results suggest a substantial role for CD8+ lymphocytes in suppressing the latency reversal effect of N-803 by promoting the maintenance of viral latency. In this study, we tested whether the use of a CD8ß-targeting antibody, which would specifically deplete CD8+ T cells, would yield similar levels of virus reactivation. We observed the induction of plasma viremia, which correlated with the efficacy of the CD8 depletion strategy.

Explanation and prediction of clinical data with imbalanced class distribution based on pattern discovery and disentanglement.

BACKGROUND: Statistical data analysis, especially the advanced machine learning (ML) methods, have attracted considerable interest in clinical practices. We are looking for interpretability of the diagnostic/prognostic results that will bring confidence to doctors, patients and their relatives in therapeutics and clinical practice. When datasets are imbalanced in diagnostic categories, we notice that the ordinary ML methods might produce results overwhelmed by the majority classes diminishing prediction accuracy. Hence, it needs methods that could produce explicit transparent and interpretable results in decision-making, without sacrificing accuracy, even for data with imbalanced groups. METHODS: In order to interpret the clinical patterns and conduct diagnostic prediction of patients with high accuracy, we develop a novel method, Pattern Discovery and Disentanglement for Clinical Data Analysis (cPDD), which is able to discover patterns (correlated traits/indicants) and use them to classify clinical data even if the class distribution is imbalanced. In the most general setting, a relational dataset is a large table such that each column represents an attribute (trait/indicant), and each row contains a set of attribute values (AVs) of an entity (patient). Compared to the existing pattern discovery approaches, cPDD can discover a small succinct set of statistically significant high-order patterns from clinical data for interpreting and predicting the disease class of the patients even with groups small and rare. RESULTS: Experiments on synthetic and thoracic clinical dataset showed that cPDD can 1) discover a smaller set of succinct significant patterns compared to other existing pattern discovery methods; 2) allow the users to interpret succinct sets of patterns coming from uncorrelated sources, even the groups are rare/small; and 3) obtain better performance in prediction compared to other interpretable classification approaches. CONCLUSIONS: In conclusion, cPDD discovers fewer patterns with greater comprehensive coverage to improve the interpretability of patterns discovered. Experimental results on synthetic data validated that cPDD discovers all patterns implanted in the data, displays them precisely and succinctly with statistical support for interpretation and prediction, a capability which the traditional ML methods lack. The success of cPDD as a novel interpretable method in solving the imbalanced class problem shows its great potential to clinical data analysis for years to come.

Review of Ilioinguinal Nerve Blocks for Ilioinguinal Neuralgia Post Hernia Surgery.

PURPOSE OF REVIEW: The purpose of this review is to evaluate the current evidence on ultrasound-guided ilioinguinal nerve blocks for ilioinguinal neuralgia post hernia surgery. METHODS: A literature search was performed to find all relevant case reports, case series, prospective or retrospective cohort studies, and randomized controlled trials (RCTs) where ultrasound-guided or landmark-based ilioinguinal nerve blocks were used for ilioinguinal neuralgia post-inguinal hernia surgery. RECENT FINDINGS: A total of six studies were identified with suitable data for inclusion. Three studies were retrospective, two studies were prospective, and one study was a randomized controlled trial. A total of 133 subjects were enrolled across these studies. Approximately 55-70% had a beneficial analgesic response to treatment. No major complications were reported in these studies. Ultrasound- and landmark-based ilioinguinal nerve blocks are safe and effective for pain relief post inguinal hernia surgery. Although there were two studies that did not show a statically significant difference in both techniques, the ultrasound-guided injection has the advantage of direct visualization of pathology, more accurate needle placement, and decreased risks of intravascular injections.

Laminar shear stress modulates endothelial luminal surface stiffness in a tissue-specific manner.

OBJECTIVE: Endothelial cells form vascular beds in all organs and are exposed to a range of mechanical forces that regulate cellular phenotype. We sought to determine the role of endothelial luminal surface stiffness in tissue-specific mechanotransduction of laminar shear stress in microvascular mouse cells and the role of arachidonic acid in mediating this response. METHODS: Microvascular mouse endothelial cells were subjected to laminar shear stress at 4 dynes/cm2 for 12 hours in parallel plate flow chambers that enabled real-time optical microscopy and atomic force microscopy measurements of cell stiffness. RESULTS: Lung endothelial cells aligned parallel to flow, while cardiac endothelial cells did not. This rapid alignment was accompanied by increased cell stiffness. The addition of arachidonic acid to cardiac endothelial cells increased alignment and stiffness in response to shear stress. Inhibition of arachidonic acid in lung endothelial cells and embryonic stem cell-derived endothelial cells prevented cellular alignment and decreased cell stiffness. CONCLUSIONS: Our findings suggest that increased endothelial luminal surface stiffness in microvascular cells may facilitate mechanotransduction and alignment in response to laminar shear stress. Furthermore, the arachidonic acid pathway may mediate this tissue-specific process. An improved understanding of this response will aid in the treatment of organ-specific vascular disease.

Partitioning and correlating subgroup characteristics from Aligned Pattern Clusters.

MOTIVATION: Evolutionarily conserved amino acids within proteins characterize functional or structural regions. Conversely, less conserved amino acids within these regions are generally areas of evolutionary divergence. A priori knowledge of biological function and species can help interpret the amino acid differences between sequences. However, this information is often erroneous or unavailable, hampering discovery with supervised algorithms. Also, most of the current unsupervised methods depend on full sequence similarity, which become inaccurate when proteins diverge (e.g. inversions, deletions, insertions). Due to these and other shortcomings, we developed a novel unsupervised algorithm which discovers highly conserved regions and uses two types of information measures: (i) data measures computed from input sequences; and (ii) class measures computed using a priori class groupings in order to reveal subgroups (i.e. classes) or functional characteristics. RESULTS: Using known and putative sequences of two proteins belonging to a relatively uncharacterized protein family we were able to group evolutionarily related sequences and identify conserved regions, which are strong homologous association patterns called Aligned Pattern Clusters, within individual proteins and across the members of this family. An initial synthetic demonstration and in silico results reveal that (i) the data measures are unbiased and (ii) our class measures can accurately rank the quality of the evolutionarily relevant groupings. Furthermore, combining our data and class measures allowed us to interpret the results by inferring regions of biological importance within the binding domain of these proteins. Compared to popular supervised methods, our algorithm has a superior runtime and comparable accuracy. AVAILABILITY AND IMPLEMENTATION: The dataset and results are available at www.pami.uwaterloo.ca/∼ealee/files/classification2015 CONTACT: akcwong@uwaterloo.ca SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

A conserved endoplasmic reticulum membrane protein complex (EMC) facilitates phospholipid transfer from the ER to mitochondria.

Mitochondrial membrane biogenesis and lipid metabolism require phospholipid transfer from the endoplasmic reticulum (ER) to mitochondria. Transfer is thought to occur at regions of close contact of these organelles and to be nonvesicular, but the mechanism is not known. Here we used a novel genetic screen in S. cerevisiae to identify mutants with defects in lipid exchange between the ER and mitochondria. We show that a strain missing multiple components of the conserved ER membrane protein complex (EMC) has decreased phosphatidylserine (PS) transfer from the ER to mitochondria. Mitochondria from this strain have significantly reduced levels of PS and its derivative phosphatidylethanolamine (PE). Cells lacking EMC proteins and the ER-mitochondria tethering complex called ERMES (the ER-mitochondria encounter structure) are inviable, suggesting that the EMC also functions as a tether. These defects are corrected by expression of an engineered ER-mitochondrial tethering protein that artificially tethers the ER to mitochondria. EMC mutants have a significant reduction in the amount of ER tethered to mitochondria even though ERMES remained intact in these mutants, suggesting that the EMC performs an additional tethering function to ERMES. We find that all Emc proteins interact with the mitochondrial translocase of the outer membrane (TOM) complex protein Tom5 and this interaction is important for PS transfer and cell growth, suggesting that the EMC forms a tether by associating with the TOM complex. Together, our findings support that the EMC tethers ER to mitochondria, which is required for phospholipid synthesis and cell growth.

Prediction of Protein-Protein Interaction via co-occurring Aligned Pattern Clusters.

Predicting Protein-Protein Interaction (PPI) is important for making new discoveries in the molecular mechanisms inside a cell. Traditionally, new PPIs are identified through biochemical experiments but such methods are labor-intensive, expensive, time-consuming and technically ineffective due to high false positive rates. Sequence-based prediction is currently the most readily applicable and cost-effective method. It exploits known PPI Databases to construct classifiers for predicting unknown PPIs based only on sequence data without requiring any other prior knowledge. Among existing sequence-based methods, most feature-based methods use exact sequence patterns with fixed length as features - a constraint which is biologically unrealistic. SVM with Pairwise String Kernel renders better predicting performance. However it is difficult to be biologically interpretable since it is kernel-based where no concrete feature values are computed. Here we have developed a novel method WeMine-P2P to overcome these drawbacks. By assuming that the regions/sites that mediate PPI are more conserved, WeMine-P2P first discovers/locates the conserved sequence patterns in protein sequences in the form of Aligned Pattern Clusters (APCs), allowing pattern variations with variable length. It then pairs up all APCs into a set of Co-Occurring APC (cAPC) pairs, and computes a cAPC-PPI score for each cAPC pair on all PPI pairs. It further constructs a feature vector composed of all cAPC pairs with their cAPC-PPI scores for each PPI pair and uses them for constructing a PPI predictor. Through 40 independent experiments, we showed that (1) WeMine-P2P outperforms the well-known algorithm, PIPE2, which also utilizes co-occurring amino acid sequence segments but does not allow variable lengths and pattern variations; (2) WeMine-P2P achieves satisfactory PPI prediction performance, comparable to the SVM-based methods particularly among unseen protein sequences with a potential reduction of feature dimension of 1280×; (3) Unlike SVM-based methods, WeMine-P2P renders interpretable biological features from which we observed that co-occurring sequence patterns from the compositional bias regions are more discriminative. WeMine-P2P is extendable to predict other biosequence interactions such as Protein-DNA interactions.

Treatment of HCV in renal transplant patients with peginterferon and ribavirin: long-term follow-up.

BACKGROUND: In addition to the observation of an increased viremia among patients with chronic hepatitis C virus (HCV) infection who undergo renal transplantation, fibrosis and necroinflammatory activity have been noted to worsen comparing pre- and post-renal transplantation liver biopsies in some of these patients. Apart from the reported reduced patient and allograft survival rates, post-transplant diabetes mellitus, de novo glomerulonephritis, and an increased overall risk of infection have been observed. However, antiviral therapy for HCV is generally considered contraindicated among patients with solid organ transplants, with the main worry being the risk of acute rejection in relation to the use of interferon. We reported the long-term outcome of four renal transplant patients with chronic HCV infection who received peginterferon-based therapy. METHODS: We collected the long-term follow-up data of four patients who completed the therapy with peginterferon in combination with ribavirin. Two of them had renal impairment at baseline. RESULTS: With treatment, they had a significant improvement in terms of serum liver transaminase level, and two patients achieved the early virological response and the other two rapid virological response. All four patients achieved sustained virological response, with neither HCV flare up nor renal dysfunction during follow-up for a mean duration of 74.3 months after therapy. CONCLUSIONS: These results suggest that sustained HCV virological response may be achieved without allograft dysfunction, in selected renal transplant patients using a peginterferon-based therapy.

Genetic variants near TNFAIP3 on 6q23 are associated with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease influenced by genetic and environmental factors. We carried out a genome-wide association scan and replication study and found an association between SLE and a variant in TNFAIP3 (rs5029939, meta-analysis P = 2.89 x 10(-12), OR = 2.29). We also found evidence of two independent signals near TNFAIP3 associated with SLE, including one previously associated with rheumatoid arthritis (RA). These results establish that variants near TNFAIP3 contribute to differential risk of SLE and RA.

Effect of Local Anesthetic Concentration (0.2% vs 0.1% Ropivacaine) on Pulmonary Function, and Analgesia After Ultrasound-Guided Interscalene Brachial Plexus Block: A Randomized Controlled Study.

OBJECTIVE: This study aims to assess diaphragmatic excursion and measure pulmonary functions as measures of the degree to which the phrenic nerve is blocked after ISB with two different concentrations of ropivacaine: 0.2% and 0.1%. DESIGN: Randomized, double-blinded study. SETTING AND PATIENTS: Ambulatory surgical facility. SUBJECTS: Fifty patients undergoing shoulder arthroscopy for rotator cuff repair. METHODS: Patients were randomized to receive ultrasound-guided ISB with 20 mL of either 0.2% or 0.1% ropivacaine. Diaphragmatic excursion was measured using M-mode ultrasound. Pulmonary functions were assessed by portable spirometer. Additional outcome data included oxygen saturation in post-anesthesia care unit (PACU), pain scores, quality of recovery scores (QOR), and opioid consumption over 72 hour period after surgery. RESULTS: Forced vital capacity (FVC) was significantly reduced 30 minutes after block placement and in PACU in the 0.2% group when compared with the 0.1% group (P = 0.04, P = 0.03, respectively). Forced expiratory volume (FEV1) was also significantly decreased in the 0.2% group in PACU when compared with the 0.1% group (P = 0.04). There were no significant differences in pain scores, length of stay, and total opioid consumption in PACU. Patients who received 0.2% ropivacaine had a longer block duration (18 vs 11.9 hours, P = 0.04) and used less opioid in the 72 hours after surgery (55 mg vs 102 mg codeine equivalents, P = 0.02), when they were compared to their counterparts who received 0.1% for their block. CONCLUSION: 0.1% ropivacaine may impair pulmonary function less than 0.2% ropivacaine. The clinical significance of these differences needs to be further studied.

Screening Algorithm for BK Virus-Associated Nephropathy Using Sequential Testing of Urinary Cytology: A Probabilistic Model Analysis.

BACKGROUND: Incorporating urinary cytology in BK virus (BKV) screening algorithm potentially reduces the screening cost for BK viral nephropathy. We aimed to evaluate the test performances and screening cost of sequential 2-stage screening consisting of urine cytology followed by BKV serum quantitative polymerase chain reaction (PCR). METHODS: Ninety-five kidney transplant recipients who had BKV serum quantitative PCR/urine cytology tested and verified with histopathology (the reference gold standard) were included. A probabilistic model was constructed to evaluate the test performance and screening cost of 2-stage screening, and was compared with screening with urine cytology or serum viral load alone. RESULTS: At a viral load threshold of ≥104 copies/ml, the sensitivity and specificity of quantitative PCR alone were 83% (95% CI 69-96) and 91% (95% CI 83-97), respectively. The sensitivity and specificity of urine cytology alone were 91% (95% CI 79-100) and 74% (95% CI 60-91), respectively. Sequential 2-stage screening resulted in loss in sensitivity but a net gain in specificity (viral load threshold ≥104 copies/ml - sensitivity, 75% (95% CI 60-91); specificity, 98% (95% CI 95-99)). Two-stage screening also had superior positive predictive value and is cost effective when BKV-associated nephropathy prevalence is below 94%. CONCLUSIONS: Our study had demonstrated a favorable test performance and cost efficiency of 2-stage BKV screening.

Discovering co-occurring patterns and their biological significance in protein families.

BACKGROUND: The large influx of biological sequences poses the importance of identifying and correlating conserved regions in homologous sequences to acquire valuable biological knowledge. These conserved regions contain statistically significant residue associations as sequence patterns. Thus, patterns from two conserved regions co-occurring frequently on the same sequences are inferred to have joint functionality. A method for finding conserved regions in protein families with frequent co-occurrence patterns is proposed. The biological significance of the discovered clusters of conserved regions with co-occurrences patterns can be validated by their three-dimensional closeness of amino acids and the biological functionality found in those regions as supported by published work. METHODS: Using existing algorithms, we discovered statistically significant amino acid associations as sequence patterns. We then aligned and clustered them into Aligned Pattern Clusters (APCs) corresponding to conserved regions with amino acid conservation and variation. When one APC frequently co-occurred with another APC, the two APCs have high co-occurrence. We then clustered APCs with high co-occurrence into what we refer to as Co-occurrence APC Clusters (Co-occurrence Clusters). RESULTS: Our results show that for Co-occurrence Clusters, the three-dimensional distance between their amino acids is closer than average amino acid distances. For the Co-occurrence Clusters of the ubiquitin and the cytochrome c families, we observed biological significance among the residing amino acids of the APCs within the same cluster. In ubiquitin, the residues are responsible for ubiquitination as well as conventional and unconventional ubiquitin-bindings. In cytochrome c, amino acids in the first co-occurrence cluster contribute to binding of other proteins in the electron transport chain, and amino acids in the second co-occurrence cluster contribute to the stability of the axial heme ligand. CONCLUSIONS: Thus, our co-occurrence clustering algorithm can efficiently find and rank conserved regions that contain patterns that frequently co-occurring on the same proteins. Co-occurring patterns are biologically significant due to their three-dimensional closeness and other evidences reported in literature. These results play an important role in drug discovery as biologists can quickly identify the target for drugs to conduct detailed preclinical studies.

Endoscopic Transsphenoidal Resection of Cystic Third Ventricular Craniopharyngioma with Cystocisternal Fenestration.

Cystic craniopharyngiomas of the third ventricle can be challenging to treat because complete resection of the cyst wall can be associated with hypothalamic dysfunction and minimal rostral displacement of the optic chiasm leads to a small endonasal operative corridor. Various methods to overcome the frequent recurrences have been described, such as intracystic bleomycin or catheter placement, with mixed results.1-12 In Video 1, we describe a simple cystocisternal fenestration technique with preservation of the rostral cyst wall via an endoscopic endonasal approach where the solid portion of the tumor is resected, and the inferior wall of the cyst is opened into the prepontine cistern and the superior wall of the cyst and adjacent third ventricle are preserved. This allows for ventricular pressure to collapse the cyst cavity in the postoperative period. In select patients where safe complete resection of a cystic craniopharyngioma is prohibitive, this may provide a durable treatment and can be performed through a small endonasal corridor below a nondisplaced optic chiasm.

Keyhole retrosigmoid approach without watertight dural closure - Evaluation of a minimalistic approach.

BACKGROUND: The retrosigmoid craniotomy is a versatile surgical approach to the cerebellopontine angle though cerebrospinal fluid leak remains a concern, with a reported prevalence of 0-22 %. A host of closure materials and strategies have been proposed to achieve a watertight dural closure to varying degrees of success. We review our series of keyhole retrosigmoid craniotomies and describe our simple, standardized method of closure without watertight dural closure. METHODS: A retrospective review of all retrosigmoid craniotomies performed by the senior author was completed. Closure was achieved by placing an oversized piece of gelatin in the subdural space. The dura is grossly approximated. An oversized sheet of collagen matrix is placed as an overlay followed by gelatin sponge in the craniectomy defect held in place with titanium mesh. The superficial layers are approximated. The skin is closed with a running sub-cuticular suture followed by skin glue. Patient demographics, cerebrospinal fluid leak risk factors, and surgical outcomes were determined. RESULTS: A total of 114 patients were included. There was one case (0.9 %) of CSF leak, which resolved with placement of a lumbar drain for 5 days. The patient had one defined risk factor (morbid obesity, BMI 41.0 kg/m2). CONCLUSIONS: Obtaining a watertight dural layer closure has been the generally accepted strategy in preventing CSF leaks in a traditional retrosigmoid approach. In keyhole retrosigmoid approaches it may not be necessary by utilizing a simple gelfoam bolstered collagen matrix onlay technique potentially improving outcome measures including operative time.

Theory and rationale of interpretable all-in-one pattern discovery and disentanglement system.

In machine learning (ML), association patterns in the data, paths in decision trees, and weights between layers of the neural network are often entangled due to multiple underlying causes, thus masking the pattern-to-source relation, weakening prediction, and defying explanation. This paper presents a revolutionary ML paradigm: pattern discovery and disentanglement (PDD) that disentangles associations and provides an all-in-one knowledge system capable of (a) disentangling patterns to associate with distinct primary sources; (b) discovering rare/imbalanced groups, detecting anomalies and rectifying discrepancies to improve class association, pattern and entity clustering; and (c) organizing knowledge for statistically supported interpretability for causal exploration. Results from case studies have validated such capabilities. The explainable knowledge reveals pattern-source relations on entities, and underlying factors for causal inference, and clinical study and practice; thus, addressing the major concern of interpretability, trust, and reliability when applying ML to healthcare, which is a step towards closing the AI chasm.

IRF5 haplotypes demonstrate diverse serological associations which predict serum interferon alpha activity and explain the majority of the genetic association with systemic lupus erythematosus.

OBJECTIVE: High serum interferon α (IFNα) activity is a heritable risk factor for systemic lupus erythematosus (SLE). Auto-antibodies found in SLE form immune complexes which can stimulate IFNα production by activating endosomal Toll-like receptors and interferon regulatory factors (IRFs), including IRF5. Genetic variation in IRF5 is associated with SLE susceptibility; however, it is unclear how IRF5 functional genetic elements contribute to human disease. METHODS: 1034 patients with SLE and 989 controls of European ancestry, 555 patients with SLE and 679 controls of African-American ancestry, and 73 patients with SLE of South African ancestry were genotyped at IRF5 polymorphisms, which define major haplotypes. Serum IFNα activity was measured using a functional assay. RESULTS: In European ancestry subjects, anti-double-stranded DNA (dsDNA) and anti-Ro antibodies were each associated with different haplotypes characterised by a different combination of functional genetic elements (OR>2.56, p<1.9×10(-14) for both). These IRF5 haplotype-auto-antibody associations strongly predicted higher serum IFNα in patients with SLE and explained >70% of the genetic risk of SLE due to IRF5. In African-American patients with SLE a similar relationship between serology and IFNα was observed, although the previously described European ancestry-risk haplotype was present at admixture proportions in African-American subjects and absent in African patients with SLE. CONCLUSIONS: The authors define a novel risk haplotype of IRF5 that is associated with anti-dsDNA antibodies and show that risk of SLE due to IRF5 genotype is largely dependent upon particular auto-antibodies. This suggests that auto-antibodies are directly pathogenic in human SLE, resulting in increased IFNα in cooperation with particular combinations of IRF5 functional genetic elements. SLE is a systemic autoimmune disorder affecting multiple organ systems including the skin, musculoskeletal, renal and haematopoietic systems. Humoral autoimmunity is a hallmark of SLE, and patients frequently have circulating auto-antibodies directed against dsDNA, as well as RNA binding proteins (RBP). Anti-RBP autoantibodies include antibodies which recognize Ro, La, Smith (anti-Sm), and ribonucleoprotein (anti-nRNP), collectively referred to as anti-retinol-binding protein). Anti-retinol-binding protein and anti-dsDNA auto-antibodies are rare in the healthy population. These auto-antibodies can be present in sera for years preceding the onset of clinical SLE illness and are likely pathogenic in SLE.

The effects of limb alignment on anterior cruciate ligament graft tunnel positions estimated from plain radiographs.

PURPOSE: The aims of this study were (1) to evaluate the femoral tunnel position after anatomic double-bundle and nonanatomic single-bundle reconstruction; (2) to evaluate the influence of rotation of the femur caused by limb malalignment on measurements of the position of the femoral ACL tunnel aperture relative to Blumensaat's line. METHODS: 3D CT scans were performed in 5 patients after anatomic double-bundle reconstruction and 5 patients after nonanatomic single-bundle reconstruction. Digitally reconstructed lateral radiographs were generated from the 3D CT scans to determine the tunnel position on the femur along and perpendicular to Blumensaat's line. The femur was then rotated to simulate internal/external and varus/valgus rotations from 0° to 15° in 5° increments. At each rotated bone position, tunnel position relative to Blumensaat's line was calculated and the difference from the lateral radiograph was calculated. RESULTS: After double-bundle reconstruction, the AM tunnel was located at 31.5 (±5.0) % along Blumensaat's line and 29.7 (±13.6) % perpendicular to Blumensaat's line, and the PL tunnel at 36.2 (±12.9) % along Blumensaat's line and 34.2 (±7.6) % perpendicular to Blumensaat's line. Valgus greater than 10° significantly affected the assessment of tunnel position (P = 0.043). After nonanatomic single-bundle reconstruction, the tunnel position was 35.4 (±15.0) % along Blumensaat's line and -2.7 (±19.4) % perpendicular to Blumensaat's line. Internal rotation of more than 10° significantly affected the assessment of tunnel position (P = 0.043). CONCLUSIONS: Tunnel position after anatomic double-bundle reconstruction and nonanatomic single-bundle reconstruction can be determined on lateral radiographs. However, valgus and internal rotation of more than 10° can introduce significant errors in tunnel position estimates. LEVEL OF EVIDENCE: Case series, Level IV.

Transtibial ACL reconstruction technique fails to position drill tunnels anatomically in vivo 3D CT study.

PURPOSE: The purpose of this study was to visualize and quantify the positions of femoral and tibial tunnels in patients who underwent traditional transtibial single-bundle ACL reconstruction, as performed by multiple surgeons, utilizing 3D CT models, and to compare these positions to our previously reported anatomical tunnel positions. METHODS: Fifty-eight knee computed tomography (CT) scans were performed on patients who underwent primary or revision transtibial single-bundle ACL reconstruction, and three-dimensional reconstructions of the CT scans were aligned within an anatomical coordinate system. The position of femoral tunnel aperture centers was measured with (1) the quadrant method and (2) in the anatomic posterior-to-anterior and proximal-to-distal directions. The position of tibia tunnel aperture centers were measured similarly, in the anterior-to-posterior and medial-to-lateral dimensions on the tibial plateau. Comparisons were made to previously established anatomical tunnel positions, and data were presented as "mean value ± standard deviation (range)." RESULTS: The location of tibial tunnels was at 48.0 ± 5.4% (35.6-59.5%) of the anterior-to-posterior plateau depth and at 47.9 ± 2.9% (42.2-57.4%) of the medial-to-lateral plateau width. The location of femoral tunnels was at 55.8 ± 8.0% (41.5-79.5%) in the anatomic posterior-to-anterior direction and at 41.2 ± 10.4% (15.1-67.4%) in the proximal-to-distal directions. Utilizing a quadrant method, femoral tunnels were positioned at 37.4 ± 5.1% (24.9-50.6%) from the proximal condylar surface, parallel to Blumensaat line, and at 11.0 ± 7.3% (-6.0-28.7%) from the notch roof, perpendicular to Blumensaat line. In summary, tibial tunnels were positioned medial to the anatomic PL position (p < 0.001), and femoral tunnels were positioned anterior to both AM and PL anatomic tunnel locations (p < 0.001 and p < 0.001). CONCLUSION: ACL reconstruction via traditional transtibial technique fails to accurately position femoral and tibial tunnels within the native ACL insertion site. To achieve anatomical graft placement, other surgical techniques should be considered. LEVEL OF EVIDENCE: IV.

Intraoperative Neuromonitoring.

Intraoperative neuromonitoring encompasses a variety of different modalities in which different neuropathways are monitored either continuously or at defined time points throughout a neurosurgical procedure. Surgical morbidity can be mitigated with careful patient selection and thoughtful implementation of the appropriate neuromonitoring modalities through the identification of eloquent areas or early detection of iatrogenic pathway disruption. Modalities covered in this article include somatosensory and motor evoked potentials, electromyography, electroencephalography, brainstem auditory evoked responses, and direct cortical stimulation.