Cardiac Comorbidity Risk Score: Zero-Burden Machine Learning to Improve Prediction of Postoperative Major Adverse Cardiac Events in Hip and Knee Arthroplasty.

Background In this retrospective, observational study we introduce the Cardiac Comorbidity Risk Score, predicting perioperative major adverse cardiac events (MACE) after elective hip and knee arthroplasty. MACE is a rare but important driver of mortality, and existing tools, eg, the Revised Cardiac Risk Index demonstrate only modest accuracy. We demonstrate an artificial intelligence-based approach to identify patients at high risk of MACE within 4 weeks (primary outcome) of arthroplasty, that imposes zero additional burden of cost/resources. Methods and Results Cardiac Comorbidity Risk Score calculation uses novel machine learning to estimate MACE risk from patient electronic health records, without requiring blood work or access to any demographic data beyond that of sex and age, and accounts for variable/missing/incomplete information across patient records. Validated on a deidentified cohort (age >45 years, n=445 391), performance was evaluated using the area under the receiver operator characteristics curve (AUROC), sensitivity/specificity, positive predictive value, and positive/negative likelihood ratios. In our cohort (age 63.5±10.5 years, 58.2% women, 34.2%/65.8% hip/knee procedures), 0.19% (882) experienced the primary outcome. Cardiac Comorbidity Risk Score achieved area under the receiver operator characteristics curve=80.0±0.4% (95% CI) for women and 80.1±0.5% (95% CI) for males, with 36.4% and 35.1% sensitivities, respectively, at 95% specificity, significantly outperforming Revised Cardiac Risk Index across all studied age-, sex-, risk-, and comorbidity-based subgroups. Conclusions Cardiac Comorbidity Risk Score, a novel artificial intelligence-based screening tool using known and unknown comorbidity patterns, outperforms state-of-the-art in predicting MACE within 4 weeks postarthroplasty, and can identify patients at high risk that do not demonstrate traditional risk factors.

Migration of Hospital Total Hip and Knee Arthroplasty Procedures to an Ambulatory Surgery Center Setting and Postsurgical Opioid Use: A Private Practice Experience.

Background: An enhanced recovery pathway using individualized multimodal pain management with scheduled nonopioid and opioid regimens previously enabled reproducible same-day discharge of Medicare beneficiaries and commercially insured patients undergoing total hip arthroplasty (THA) or total knee arthroplasty (TKA) procedures in the hospital or in ambulatory surgery center settings. Objective: To analyze the migration trends for TKA and THA procedures from a hospital to an ambulatory surgery center facility and to assess perioperative outcomes before and after incorporating liposomal bupivacaine into a multimodal pain management regimen for these procedures. Methods: This retrospective medical chart review study included patients undergoing THA or TKA with an enhanced recovery pathway in a hospital or an ambulatory surgery center between 2013 and 2019. The outcome measures included length of stay at the hospital or the ambulatory center, and opioid consumption. We compared the outcomes before and after the addition of liposomal bupivacaine to surgeon-applied periarticular intraoperative local anesthetic field blocks between in-hospital patients who received and patients who did not receive liposomal bupivacaine in 2013 and 2014, and the impact of liposomal bupivacaine use in the hospital versus the ambulatory center from 2015 to 2019. Results: In 2013 and 2014, the addition of liposomal bupivacaine increased the same-day hospital discharge rate to 32% versus 4% without liposomal bupivacaine (odds ratio, 14.3; 95% confidence interval, 5.9-33.3; P <.0001); the same-day hospital discharge rates increased to 73% in 2015. From 2015 through 2019, 89% of all patients were discharged on the same day from the hospital. In-hospital opioid use was 22% lower in the liposomal bupivacaine cohort than in the patients who did not receive this medication (P = .0035). In 2018 and 2019, same-day discharge from the hospital or the ambulatory surgery center rates were 96% and 100%, respectively, and 84% of the patients used postsurgical opioid prescriptions of 30 or fewer tablets. The complication rates and healthcare resource utilization did not increase with the incorporation of liposomal bupivacaine into the enhanced recovery pathway and increased same-day discharge rates. Conclusion: An enhanced recovery pathway using individualized, scheduled multimodal pain management protocol in patients undergoing THA or TKA facilitated reproducible, high same-day discharge rates and low postoperative opioid consumption. These results suggest that the use of liposomal bupivacaine for intraoperative field blocks supports predictable same-day discharge rates after THA or TKA. This protocol could facilitate same-day hospital discharge and the migration of THA and TKA procedures from the hospital to lower-cost ambulatory surgery centers.

Selective Binding of Small Molecules to Vibrio cholerae DsbA Offers a Starting Point for the Design of Novel Antibacterials.

DsbA enzymes catalyze oxidative folding of proteins that are secreted into the periplasm of Gram-negative bacteria, and they are indispensable for the virulence of human pathogens such as Vibrio cholerae and Escherichia coli. Therefore, targeting DsbA represents an attractive approach to control bacterial virulence. X-ray crystal structures reveal that DsbA enzymes share a similar fold, however, the hydrophobic groove adjacent to the active site, which is implicated in substrate binding, is shorter and flatter in the structure of V. cholerae DsbA (VcDsbA) compared to E. coli DsbA (EcDsbA). The flat and largely featureless nature of this hydrophobic groove is challenging for the development of small molecule inhibitors. Using fragment-based screening approaches, we have identified a novel small molecule, based on the benzimidazole scaffold, that binds to the hydrophobic groove of oxidized VcDsbA with a KD of 446±10 µM. The same benzimidazole compound has ∼8-fold selectivity for VcDsbA over EcDsbA and binds to oxidized EcDsbA, with KD >3.5 mM. We generated a model of the benzimidazole complex with VcDsbA using NMR data but were unable to determine the structure of the benzimidazole bound EcDsbA using either NMR or X-ray crystallography. Therefore, a structural basis for the observed selectivity is unclear. To better understand ligand binding to these two enzymes we crystallized each of them in complex with a known ligand, the bile salt sodium taurocholate. The crystal structures show that taurocholate adopts different binding poses in complex with VcDsbA and EcDsbA, and reveal the protein-ligand interactions that stabilize the different modes of binding. This work highlights the capacity of fragment-based drug discovery to identify inhibitors of challenging protein targets. In addition, it provides a starting point for development of more potent and specific VcDsbA inhibitors that act through a novel anti-virulence mechanism.

Reduced false positives in autism screening via digital biomarkers inferred from deep comorbidity patterns.

Here, we develop digital biomarkers for autism spectrum disorder (ASD), computed from patterns of past medical encounters, identifying children at high risk with an area under the receiver operating characteristic exceeding 80% from shortly after 2 years of age for either sex, and across two independent patient databases. We leverage uncharted ASD comorbidities, with no requirement of additional blood work, or procedures, to estimate the autism comorbid risk score (ACoR), during the earliest years when interventions are the most effective. ACoR has superior predictive performance to common questionnaire-based screenings and can reduce their current socioeconomic, ethnic, and demographic biases. In addition, we can condition on current screening scores to either halve the state-of-the-art false-positive rate or boost sensitivity to over 60%, while maintaining specificity above 95%. Thus, ACoR can significantly reduce the median diagnostic age, reducing diagnostic delays and accelerating access to evidence-based interventions.

I think I'm sleepy, therefore I am - Awareness of sleepiness while driving: A systematic review.

Driver drowsiness contributes to 10-20% of motor vehicle crashes. To reduce crash risk, ideally drivers would be aware of the drowsy state and cease driving. The extent to which drivers can accurately identify sleepiness remains under much debate. We systematically examined whether individuals are aware of sleepiness while driving, and whether this accurately reflects driving impairment, using meta-analyses and narrative review. Within this scope, there is high variability in measures of subjective sleepiness, driving performance and physiologically-derived drowsiness, and statistical analyses. Thirty-four simulated/naturalistic driving studies were reviewed. To summarise, drivers were aware of sleepiness, and this was associated to physiological drowsiness and driving impairment, such that high levels of sleepiness significantly predicted crash events and lane deviations. Subjective sleepiness was more strongly correlated (i) with physiological drowsiness compared to driving outcomes; (ii) under simulated driving conditions compared to naturalistic drives; and (iii) when examined using the Karolinska sleepiness scale (KSS) compared to other measures. Gaps remain in relation to how age, sex, and varying degrees of sleep loss may influence this association. This review provides evidence that drivers are aware of drowsiness while driving, and stopping driving when feeling 'sleepy' may significantly reduce crash risk.

Synthesis of Arylpalladium(II) Boronates: Confirming the Structure and Chemical Competence of Pre-transmetalation Intermediates in the Suzuki-Miyaura Reaction.

Palladium(II) boronates are recognized as fundamental pre-transmetalation intermediates in Suzuki-Miyaura cross-couplings. While these typically transient species have been detected and studied spectroscopically, it is conspicuous that they have never been isolated since this important reaction was discovered over forty years ago. This study reports the synthesis of a family of unprecedented arylpalladium(II) boronates that are, by design, kinetically stable at ambient temperature, both in solution and in the solid state. These properties enabled unambiguous crystallographic confirmation of their structure for the first time and their chemical competence in a Suzuki-Miyaura reaction was demonstrated.

Presurgical optimization and opioid-minimizing enhanced recovery pathway for ambulatory knee and hip arthroplasty: postsurgical opioid use and clinical outcomes.

BACKGROUND: Enhanced recovery after surgery (ERAS) pathways offer approaches to achieve successful ambulatory primary total knee and total hip arthroplasty (TKA/THA) while meeting the "Triple Aim" of healthcare: patient satisfaction, population health, and value. We evaluated outcomes from an ERAS pathway designed to maximize patients' eligibility for ambulatory TKA/THA while reducing costs, complications, and postsurgical opioid use. METHODS: This retrospective study included 220 consecutive unique commercially insured patients who underwent TKA (n = 113) or THA (n = 138) in an ambulatory surgery center between June 1, 2015 and November 16, 2017. The ERAS pathway encompassed early presurgical through home recovery periods. Key elements included presurgical patient engagement; creation of realistic expectations; optimization of modifiable medical, physical, and social factors; and creation of individualized multimodal opioid-sparing pain management. No home services were used. Adverse events and unplanned admissions within 30 and 60 days, satisfaction, and opioid use were analyzed descriptively. RESULTS: All patients (mean [range] age, 58 [22-84] years; 49% women) had same-day discharge. Within 30 days, 7 (2.8%) patients experienced an adverse event, 3 (1.2%) had an emergency department or urgent care visit without admission, and 8 (3.2%) had an unplanned admission. Within 60 days, 3 additional patients had an emergency department/urgent care visit. Most patients (206 [82.1%]) did not require a second opioid prescription. Patient satisfaction was high. CONCLUSIONS: This ERAS pathway may help meet the Triple Aim for outpatient joint replacement, expand the eligible patient population, and reduce postsurgical opioid use. Further research is warranted.

Patient-optimizing enhanced recovery pathways for total knee and hip arthroplasty in Medicare patients: implication for transition to ambulatory surgery centers.

BACKGROUND: Medicare-insured patients may be candidates for outpatient total knee and hip arthroplasty (TKA/THA) because postsurgical complications are often age unrelated. We evaluated an opioid-minimizing enhanced recovery after surgery (ERAS) pathway in an inpatient setting designed to presurgically optimize and prepare patients to reduce risk of avoidable postsurgical complications and maximize feasibility of same-day discharge. METHODS: This single-center retrospective chart review included 601 unique consecutive Medicare-insured patients who underwent TKA (n = 337) or THA (n = 308) between June 1, 2015 and November 16, 2017. The ERAS pathway included presurgical nonarthroplasty treatment of osteoarthritis; physical, medical, and social optimization; and medication trials to individualize perioperative analgesia. All patients were discharged directly home without home services. Adverse events, satisfaction, and opioid use were analyzed descriptively. RESULTS: Mean (range) age was 72 (32-92) years; 56.7% of patients were women; 84.0% were discharged the same day, 13.8% in 1 day, and 2.2% in >1 day. Rates of minor and severe adverse events within 30 days were 0.5% and 1.1%, respectively. There were no intubations, sepsis, or deaths. Twelve patients (1.9%) had unplanned readmissions within 30 days. Patient-reported satisfaction with facility, analgesia, and communication were high. Most patients (84.2%) did not require >1 seven-day opioid prescription from the surgeon within 8 weeks postsurgery. CONCLUSIONS: Using a patient-optimizing, opioid-minimizing ERAS pathway without home services, Medicare-insured patients undergoing TKA/THA experienced low complication rates and high satisfaction. Exploratory analysis suggests limited postsurgical opioid use. This presurgical patient-engagement approach may aid transition to freestanding ambulatory surgery centers.

A Robust Metatranscriptomic Technology for Population-Scale Studies of Diet, Gut Microbiome, and Human Health.

A functional readout of the gut microbiome is necessary to enable precise control of the gut microbiome's functions, which support human health and prevent or minimize a wide range of chronic diseases. Stool metatranscriptomic analysis offers a comprehensive functional view of the gut microbiome, but despite its usefulness, it has rarely been used in clinical studies due to its complexity, cost, and bioinformatic challenges. This method has also received criticism due to potential intrasample variability, rapid changes, and RNA degradation. Here, we describe a robust and automated stool metatranscriptomic method, called Viomega, which was specifically developed for population-scale studies. Viomega includes sample collection, ambient temperature sample preservation, total RNA extraction, physical removal of ribosomal RNAs (rRNAs), preparation of directional Illumina libraries, Illumina sequencing, taxonomic classification based on a database of >110,000 microbial genomes, and quantitative microbial gene expression analysis using a database of ~100 million microbial genes. We applied this method to 10,000 human stool samples and performed several small-scale studies to demonstrate sample stability and consistency. In summary, Viomega is an inexpensive, high-throughput, automated, and accurate sample-to-result stool metatranscriptomic technology platform for large-scale studies and a wide range of applications.

Structural properties of a haemophore facilitate targeted elimination of the pathogen Porphyromonas gingivalis.

Porphyromonas gingivalis is a keystone bacterial pathogen of chronic periodontitis. P. gingivalis is unable to synthesise the porphyrin macrocycle and relies on exogenous porphyrin, including haem or haem biosynthesis intermediates from host sources. We show that under the iron-limited conditions prevailing in tissue environments, P. gingivalis expresses a haemophore-like protein, HusA, to mediate the uptake of essential porphyrin and support pathogen survival within epithelial cells. The structure of HusA, together with titration studies, mutagenesis and in silico docking, show that haem binds in a hydrophobic groove on the α-helical structure without the typical iron coordination seen in other haemophores. This mode of interaction allows HusA to bind to a variety of abiotic and metal-free porphyrins with higher affinities than to haem. We exploit this unusual porphyrin-binding activity of HusA to target a prototypic deuteroporphyrin-metronidazole conjugate with restricted antimicrobial specificity in a Trojan horse strategy that effectively kills intracellular P. gingivalis.

Highly Cross-Linked Polyethylene Reduces Wear and Revision Rates in Total Hip Arthroplasty: A 10-Year Double-Blinded Randomized Controlled Trial.

BACKGROUND: Highly cross-linked polyethylene (XLPE) was developed to address the problem of wear and osteolysis associated with metal-on-conventional ultra-high molecular weight polyethylene (UHMWPE) bearing surfaces. The purpose of this study was to compare in vivo wear rates and clinical and radiographic outcomes between XLPE and UHMWPE in a prospective double-blinded randomized controlled trial with a minimum of 10 years of follow-up. METHODS: We randomized 122 patients to receive either a conventional UHMWPE liner (Enduron; DePuy) or an XLPE liner (Marathon; DePuy). Ninety-one patients were assessed clinically and radiographically at a minimum of 10 years (range, 10.08 to 12.17 years). Oxford Hip Scores and Short Form-12 Health Survey scores were collected. The radiographs were analyzed for osteolysis and for 2-dimensional (2-D), 3-dimensional (3-D), and volumetric wear using validated software. RESULTS: All 122 patients were accounted for at the 10-year follow-up evaluation. Twelve patients had undergone revision surgery, 21 patients had died (1 of whom had previously undergone revision surgery), and 2 patients were unable to return for follow-up, leaving 91 patients available for clinical and radiographic evaluation. At a minimum of 10 years, 3-D wear rates were significantly lower (p < 0.001) in the XLPE group (mean, 0.03 mm/yr) than in the conventional UHMWPE group (mean, 0.27 mm/yr). The prevalence of osteolysis was also significantly lower in the XLPE group (38% versus 8%, p < 0.005), as was the revision rate (14.6% versus 1.9%, p = 0.012), with 10 of the 12 revisions being in the Enduron group. There was no significant difference between the clinical scores of the 2 groups. CONCLUSIONS: XLPE liners have significantly reduced wear and are associated with a greater implant survival rate at 10 years compared with conventional UHMWPE liners. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

ent-Labdane Diterpenoids from Dodonaea viscosa.

Seven new and two known ent-labdane diterpenoids have been isolated from a single plant specimen of Dodonaea viscosa ssp. spatulata, found in Tasmania, Australia. Prior to this study, only seven different labdane diterpenoids had been isolated from D. viscosa. The structures of the natural products were assigned via 1D and 2D NMR spectroscopy and other standard spectroscopic methods. The absolute configuration of three ent-labdane diterpenoids was determined by single-crystal X-ray crystallography of synthetic derivatives. Significantly, the results of this study suggest that the absolute configuration of some known labdane diterpenoids may have been misassigned.

Serum metabolic profile predicts adverse central haemodynamics in patients with type 2 diabetes mellitus.

AIMS: People with type 2 diabetes mellitus (T2DM) have abnormal peripheral and central haemodynamics at rest and during exercise, probably due to metabolic perturbations, but mechanisms are unknown. We used untargeted metabolomics to determine the relationships between metabolic perturbations and haemodynamics (peripheral and central) measured at rest and during exercise. METHODS: Serum samples from 39 participants with T2DM (62 ± 9 years; 46 % male) and 39 controls (52 ± 10 years; 51 % male) were analysed by liquid chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy and principal component analysis. Scores on principal components (PC) were used to assess relationships with haemodynamics including peripheral and central BP, central augmentation index (AIx) and central augmentation pressure (AP). RESULTS: Participants with T2DM had higher resting and exercise haemodynamics (peripheral and central BP, central AIx and central AP) compared to controls (p < 0.05). PC that comprised of a signature metabolic pattern of T2DM was independently associated with resting and exercise central AIx and central AP (p < 0.05). CONCLUSIONS: Serum metabolic profile was associated with central, but not peripheral, haemodynamics in T2DM participants, suggesting that metabolic irregularities may explain abnormal central haemodynamics in T2DM patients.

Human REM sleep: influence on feeding behaviour, with clinical implications.

Rapid eye movement (REM) sleep shares many underlying mechanisms with wakefulness, to a much greater extent than does non-REM, especially those relating to feeding behaviours, appetite, curiosity, exploratory (locomotor) activities, as well as aspects of emotions, particularly 'fear extinction'. REM is most evident in infancy, thereafter declining in what seems to be a dispensable manner that largely reciprocates increasing wakefulness. However, human adults retain more REM than do other mammals, where for us it is most abundant during our usual final REM period (fREMP) of the night, nearing wakefulness. The case is made that our REM is unusual, and that (i) fREMP retains this 'dispensability', acting as a proxy for wakefulness, able to be forfeited (without REM rebound) and substituted by physical activity (locomotion) when pressures of wakefulness increase; (ii) REM's atonia (inhibited motor output) may be a proxy for this locomotion; (iii) our nocturnal sleep typically develops into a physiological fast, especially during fREMP, which is also an appetite suppressant; (iv) REM may have 'anti-obesity' properties, and that the loss of fREMP may well enhance appetite and contribute to weight gain ('overeating') in habitually short sleepers; (v) as we also select foods for their hedonic (emotional) values, REM may be integral to developing food preferences and dislikes; and (vii) REM seems to have wider influences in regulating energy balance in terms of exercise 'substitution' and energy (body heat) retention. Avenues for further research are proposed, linking REM with feeding behaviours, including eating disorders, and effects of REM-suppressant medications.

Non-Anticoagulant Fractions of Enoxaparin Suppress Inflammatory Cytokine Release from Peripheral Blood Mononuclear Cells of Allergic Asthmatic Individuals.

BACKGROUND: Enoxaparin, a low-molecular-weight heparin, is known to possess anti-inflammatory properties. However, its clinical exploitation as an anti-inflammatory agent is hampered by its anticoagulant effect and the associated risk of bleeding. OBJECTIVE: The aim of the current study was to examine the ability of non-anticoagulant fractions of enoxaparin to inhibit the release of key inflammatory cytokines in primed peripheral blood mononuclear cells derived from allergic mild asthmatics. METHODS: Peripheral blood mononuclear cells from allergic asthmatics were activated with phytohaemag glutinin (PHA), concanavalin-A (ConA) or phorbol 12-myristate 13-acetate (PMA) in the presence or absence of enoxaparin fractions before cytokine levels were quantified using specific cytokine bead arrays. Together with nuclear magnetic resonance analysis,time-dependent and target-specific effects of enoxaparin fractions were used to elucidate structural determinants for their anti-inflammatory effect and gain mechanistic insights into their anti-inflammatory activity. RESULTS: Two non-anticoagulant fractions of enoxaparin were identified that significantly inhibited T-cell activation. A disaccharide fraction of enoxaparin inhibited the release of IL-4, IL-5, IL-13 and TNF-α by more than 57% while a tetrasaccharide fraction was found to inhibit the release of tested cytokines by more than 68%. Our data suggest that the observed response is likely to be due to an interaction of 6-O-sulfated tetrasaccharide with cellular receptor(s). CONCLUSION AND CLINICAL RELEVANCE: The two identified anti-inflammatory fractions lacked anticoagulant activity and are therefore not associated with risk of bleeding. The findings highlight the potential therapeutic use of enoxaparin-derived fractions, in particular tetrasaccharide, in patients with chronic inflammatory disorders.

In-vitro suppression of IL-6 and IL-8 release from human pulmonary epithelial cells by non-anticoagulant fraction of enoxaparin.

BACKGROUND: Enoxaparin, a mixture of anticoagulant and non-anticoagulant fractions, is widely used as an anticoagulant agent. However, it is also reported to possess anti-inflammatory properties. Our study indicated that enoxaparin inhibits the release of IL-6 and IL-8 from A549 pulmonary epithelial cells. Their release causes extensive lung tissue damage. The use of enoxaparin as an anti-inflammatory agent is hampered due to the risk of bleeding associated with its anticoagulant fractions. Therefore, we aimed to identify the fraction responsible for the observed anti-inflammatory effect of enoxaparin and to determine the relationship between its structure and biological activities. METHODS: A549 pulmonary epithelial cells were pre-treated in the presence of enoxaparin and its fractions. The levels of IL-6 and IL-8 released from the trypsin-stimulated cells were measured by ELISA. The anticoagulant activity of the fraction responsible for the effect of enoxaparin was determined using an anti-factor-Xa assay. The fraction was structurally characterised using nuclear magnetic resonance. The fraction was 2-O, 6-O or N-desulfated to determine the position of sulfate groups required for the inhibition of interleukins. High-performance size-exclusion chromatography was performed to rule out that the observed effect was due to the interaction between the fraction and trypsin or interleukins. RESULTS: Enoxaparin (60 µg/mL) inhibited the release of IL-6 and IL-8 by >30%. The fraction responsible for this effect of enoxaparin was found to be a disaccharide composed of α-L-iduronic-acid and α-D-glucosamine-6-sulfate. It (15 µg/mL) inhibited the release of interleukins by >70%. The 6-O sulphate groups were responsible for its anti-inflammatory effect. The fraction did not bind to trypsin or interleukins, suggesting the effect was not due to an artefact of the experimental model. CONCLUSION: The identified disaccharide has no anticoagulant activity and therefore eliminates the risk of bleeding associated with enoxaparin. Future in-vivo studies should be designed to validate findings of the current study.

Polyubiquitin Drives the Molecular Interactions of the NF-κB Essential Modulator (NEMO) by Allosteric Regulation.

The NF-κB essential modulator (NEMO) is the master regulator of NF-κB signaling, controlling the immune and nervous systems. NEMO affects the activity of IκB kinase-ß (IKKß), which relieves the inhibition of the NF-κB transcriptional regulation machinery. Despite major effort, there is only a very sparse, phenomenological understanding of how NEMO regulates IKKß and shows specificity in its large range of molecular interactions. We explore the key molecular interactions of NEMO using a molecular biophysics approach, incorporating rapid-mixing stopped-flow, high-pressure, and CD spectroscopies. Our study demonstrates that NEMO has a significant degree of native structural disorder and that molecular flexibility and ligand-induced conformational change are at the heart of the molecular interactions of NEMO. We found that long chain length, unanchored, linear polyubiquitin drives NEMO activity, enhancing the affinity of NEMO for IKKß and the kinase substrate IκBα and promoting membrane association. We present evidence that unanchored polyubiquitin achieves this regulation by inducing NEMO conformational change by an allosteric mechanism. We combine our quantitative findings to give a detailed molecular mechanistic model for the activity of NEMO, providing insight into the molecular mechanism of NEMO activity with broad implications for the biological role of free polyubiquitin.

Application of fragment-based screening to the design of inhibitors of Escherichia coli DsbA.

The thiol-disulfide oxidoreductase enzyme DsbA catalyzes the formation of disulfide bonds in the periplasm of Gram-negative bacteria. DsbA substrates include proteins involved in bacterial virulence. In the absence of DsbA, many of these proteins do not fold correctly, which renders the bacteria avirulent. Thus DsbA is a critical mediator of virulence and inhibitors may act as antivirulence agents. Biophysical screening has been employed to identify fragments that bind to DsbA from Escherichia coli. Elaboration of one of these fragments produced compounds that inhibit DsbA activity in vitro. In cell-based assays, the compounds inhibit bacterial motility, but have no effect on growth in liquid culture, which is consistent with selective inhibition of DsbA. Crystal structures of inhibitors bound to DsbA indicate that they bind adjacent to the active site. Together, the data suggest that DsbA may be amenable to the development of novel antibacterial compounds that act by inhibiting bacterial virulence.

Relationship of plasma metal ions and clinical and imaging findings in patients with ASR XL metal-on-metal total hip replacements.

BACKGROUND: Plasma metal ion levels are commonly used in the postoperative follow-up evaluation of patients who have had a metal-on-metal hip arthroplasty. However, the relationship between these levels and clinical and imaging findings is not well known. METHODS: We evaluated 156 consecutive patients who received a unilateral ASR XL total hip replacement. Patients presented, regardless of symptoms, in response to a voluntary recall of the hip replacement by the manufacturer and were assessed with regard to the presence and type of symptoms and plasma cobalt-chromium levels. In addition, radiographic and magnetic resonance imaging studies were performed and analyzed. RESULTS: Eighty patients were asymptomatic, and seventy-six patients were symptomatic. The median cobalt level was 1.8 ppb, and the median chromium level was 1.0 ppb (at or below measurement threshold). Pseudotumors that could be detected on magnetic resonance imaging were seen in 69% (107) of 156 patients, and radiographic osteolysis was evident in 7% (eleven patients). At a threshold of 5 ppb, no association was detected between abnormal metal ion levels and patient symptoms, prosthetic femoral head size, or acetabular cup inclination. An abnormal cobalt level was significantly associated with the presence of periprosthetic lucency on radiographs and pseudotumor on magnetic resonance imaging (p < 0.05). An abnormal chromium level showed a similar pattern, but the relationships did not reach significance. Both abnormal plasma cobalt and chromium levels were associated with larger sizes of pseudotumor when present (p < 0.05). CONCLUSIONS: In our sample, with a threshold of 5 ppb, abnormal plasma metal ions were associated with larger sizes of pseudotumors when present, but were not predictive of patient symptoms. Abnormal plasma cobalt levels have a significant association with periprosthetic lucency and presence of pseudotumor. Plasma chromium shows a similar pattern of association with lucency and presence of pseudotumor, although the relationships were not significant. Metal ion analysis should be used in conjunction with clinical and imaging evaluation and not as a sole indirect screening test when evaluating patients following metal-on-metal hip arthroplasty.

Driving drowsy also worsens driver distraction.

OBJECTIVES: Laboratory-based studies show that drowsiness increases the propensity to become distracted. As this phenomenon has not been investigated in drowsy drivers, we underwent a pilot study under realistic monotonous driving conditions to see if distraction was more apparent when drowsy; if so, how does it affect driving performance? METHODS: A repeated measures counterbalanced design whereby participants drove for two hours in a fully interactive car simulator during the bi circadian afternoon drive, after a night of either normal (baseline) or restricted sleep to five hours (sleep restriction). Videos of drivers' faces were analysed blind for short (<3 s) and long (>3 s) distractions, in which drivers took their eyes off the road ahead. These results were compared with the likelihood of simultaneous lane-drifting incidents, when at least two wheels left the driving lane. RESULTS: More distractions occurred after restricted sleep (p<0.005) for both short and long distractions (p<0.05). There was an overall significant (p<0.02) positive correlation between distractions and driving incidents for both conditions but with significantly more distraction-related incidents after sleep restriction (p<0.03). CONCLUSIONS: Following restricted sleep, drivers had an increased propensity to become distracted, which was associated with an increased likelihood of poor driving performance as evidenced by the car leaving the driving lane.