Out-of-hours emergent surgery for degenerative spinal disease in Canada: a retrospective cohort study from a national registry.

Background: Spinal degenerative disease represents a growing burden on our healthcare system, yet little is known about longitudinal trends in access and care. Our goal was to provide an essential portrait of surgical volume trends for degenerative spinal pathologies within Canada. Methods: The Canadian Institute for Health Information (CIHI) database was used to identify all patients receiving surgery for a degenerative spinal condition from 2006 to 2019. Trends in number of interventions, unscheduled vs scheduled hospitalizations, in-hours vs out-of-hours interventions, resource utilization and adverse events were analyzed retrospectively using linear regression models. Confidence intervals were reported in the expected count ratio scale (CR). Findings: A total of 338,629 spinal interventions and 256,360 hospitalizations between 2006 and 2019 were analyzed. The mean and SD of the annual mean age of patients was 55.5 (SD 1.6) for elective hospitalizations and 55.6 (SD 1.6) for emergent hospitalizations. The proportion of female patients was 47.8% (91,789/192,027) for elective hospitalizations and 41.4% (26,633/64,333) for emergent hospitalizations. Elective hospitalizations increased an average of 2.0% per year, with CR = 1.020 (95% CI 1.017-1.023, p < 0.0001) while emergent hospitalizations exhibited more rapid growth with an average 3.4% annually, with CR 1.034 (95% CI 1.027-1.040, p < 0.0001). «In-hours ¼ surgeries increased on average 2.7% per year, with CR 1.027 (95% CI 1.021-1.033, p < 0.0001), while « out-of-hours ¼ surgeries increased 6.1% annually, with CR 1.061 (95% CI 1.051-1.071, p < 0.0001). The resource utilization for unscheduled hospitalizations approximates two and a half times that of scheduled hospitalizations. The proportions of spinal interventions with at least one adverse event increased on average 6.3% per year, with CR 1.063 (95% CI 1.049-1.077, p < 0.0001). Interpretation: This study provides novel data critical for all providers and stakeholders. The rapid growth of emergent out-of-hours hospitalizations demonstrates that the needs of this growing patient population have far exceeded health-care resource allocations. Future studies will analyze the health-related quality of life implications of this system shift and identify demographic and socioeconomic inequities in access to surgical care. Funding: This work was funded by the Bob and Trish Saunders Spine Research Fund through The VGH and UBC Hospital Foundation. The funder of the study had no role in the study design, data collection, data analysis, data interpretation, or writing of the manuscript.

The Learning Curve for Robotic Lateral Pelvic Lymph Node Dissection for Rectal Cancer: A View from the West.

BACKGROUND: Lateral pelvic lymph-node dissection is performed for selected patients with rectal cancer with persistent lateral nodal disease after neoadjuvant therapy. This technique has been slow to be adopted in the West due to concerns regarding technical difficulty. This is the first report on the learning curve for lateral pelvic lymph node dissection in the US or Europe. OBJECTIVE: The aim of this study was to analyze the learning curve associated with robotic lateral pelvic lymph node dissection. DESIGN: Retrospective observational cohort. SETTING: Tertiary academic cancer center. PATIENTS: Consecutive patients from 2012 to 2021. INTERVENTION: All patients underwent robotic lateral pelvic lymph node dissection. MAIN OUTCOME MEASURES: The primary endpoints were the learning curves for maximum number of nodes retrieved and urinary retention which was evaluated with simple cumulative-sum and two-sided Bernoulli cumulative-sum charts. RESULTS: Fifty-four procedures were included. A single-surgeon (n = 35) and an institutional learning curve are presented in the analysis. In the single-surgeon learning curve, a turning point marking the end of a learning phase was detected at the 12th procedure for the number of retrieved nodes and at the 20th for urinary retention. In the institutional learning curve analysis, two turning points were identified at the 13th and 26th procedures indicating progressive improvements for the number of retrieved nodes and at the 27th for urinary retention. No sustained alarm signals were detected at any time point. LIMITATIONS: The retrospective nature, small sample size and the referral center nature of the reporting institution that may limit generalizability. CONCLUSIONS: In a setting of institutional experience with robotic colorectal surgery including beyond TME resections, the learning curve for robotic lateral pelvic lymph node dissection is acceptably short. Our results demonstrate feasibility of acquisition of this technique in a controlled setting, with sufficient case volume and proctoring can optimize the learning curve. See Video Abstract.

Early Postoperative Prediction of Complications and Readmission After Colorectal Cancer Surgery Using an Artificial Neural Network.

BACKGROUND: Early predictors of postoperative complications can risk-stratify patients undergoing colorectal cancer surgery. However, conventional regression models have limited power to identify complex nonlinear relationships among a large set of variables. We developed artificial neural network models to optimize the prediction of major postoperative complications and risk of readmission in patients undergoing colorectal cancer surgery. OBJECTIVE: The aim of this study was to develop an artificial neural network model to predict postoperative complications using postoperative laboratory values, and compare these models' accuracy to standard regression methods. DESIGN: This retrospective study included patients who underwent elective colorectal cancer resection between January 1, 2016, and July 31, 2021. Clinical data, cancer stage, and laboratory data from postoperative day 1 to 3 were collected. Models of complications and readmission risk were created using multivariable logistic regression and single-layer neural networks. SETTING: National Cancer Institute-Designated Comprehensive Cancer Center. PATIENTS: Adult colorectal cancer patients. MAIN OUTCOME MEASURES: Accuracy of predicting postoperative major complication, readmission and anastomotic leak using the area under the receiver-operating characteristic curve. RESULTS: Neural networks had larger areas under the curve for predicting major complications compared to regression models (neural network 0.811; regression model 0.724, p < 0.001). Neural networks also showed an advantage in predicting anastomotic leak (p = 0.036) and readmission using postoperative day 1-2 values (p = 0.014). LIMITATIONS: Single-center, retrospective design limited to cancer operations. CONCLUSIONS: In this study, we generated a set of models for early prediction of complications after colorectal surgery. The neural network models provided greater discrimination than the models based on traditional logistic regression. These models may allow for early detection of postoperative complications as soon as postoperative day 2. See Video Abstract.

Urine sodium concentration and 28-day weight velocity in preterm infants: A retrospective cohort study.

BACKGROUND: Urine sodium concentration has been suggested as a marker to guide enteral sodium supplementation in preterm infants; however, no previous data have demonstrated relationships between urine sodium concentration and postnatal growth. METHODS: We performed a single-center retrospective cohort study on 224 preterm infants admitted to the neonatal intensive care unit at the Children's Hospital of Georgia between January 2010 and July 2022. Spot urine sodium was measured in preterm infants (<34 weeks postmenstrual age [PMA]) between days of life (DOLs) 7 and 28. Our exposure of interest was spot urine sodium concentration (milliequivalents per liter) obtained between postnatal days 7 and 28, and our primary outcome was weight velocity (grams per kilograms per day) determined at DOL 28. Statistical relationships were assessed by multivariate analysis with subgroup comparisons by Student t test and analysis of variance. RESULTS: In 224 preterm infants (199 ± 17 days, 56% male, 71% Black), urine sodium concentration did not associate with weight velocity at DOL 28 and 36 weeks PMA. Urine sodium concentration was weakly associated with gestational age at birth, and Black preterm infants had higher urine sodium values when compared with "other," but not White preterm infants. CONCLUSION: Spot urine sodium during the first month of life does not associate with weight velocity at DOL 28 or 36 weeks PMA.

ROR2 Regulates Cellular Plasticity in Pancreatic Neoplasia and Adenocarcinoma.

Cellular plasticity is a hallmark of pancreatic ductal adenocarcinoma (PDAC) starting from the conversion of normal cells into precancerous lesions, to the progression of carcinoma subtypes associated with aggressiveness and therapeutic response. We discovered that normal acinar cell differentiation, maintained by the transcription factor Pdx1, suppresses a broad gastric cell identity that is maintained in metaplasia, neoplasia, and the classical subtype of PDAC in mouse and human. We have identified the receptor tyrosine kinase Ror2 as marker of a gastric metaplasia-like identity in pancreas neoplasms. Ablation of Ror2 in a mouse model of pancreatic tumorigenesis promoted a switch to a gastric pit cell identity that largely persisted through progression to the classical subtype of PDAC. In both human and mouse pancreatic cancer, ROR2 activity continued to antagonize the gastric pit cell identity, strongly promoting an epithelial to mesenchymal transition, conferring resistance to KRAS inhibition, and vulnerability to AKT inhibition.

Physiology, fast and slow: bacterial response to variable resource stoichiometry and dilution rate.

Microorganisms grow despite imbalances in the availability of nutrients and energy. The biochemical and elemental adjustments that bacteria employ to sustain growth when these resources are suboptimal are not well understood. We assessed how Pseudomonas putida KT2440 adjusts its physiology at differing dilution rates (to approximate growth rates) in response to carbon (C), nitrogen (N), and phosphorus (P) stress using chemostats. Cellular elemental and biomolecular pools were variable in response to different limiting resources at a slow dilution rate of 0.12 h-1, but these pools were more similar across treatments at a faster rate of 0.48 h-1. At slow dilution rates, limitation by P and C appeared to alter cell growth efficiencies as reflected by changes in cellular C quotas and rates of oxygen consumption, both of which were highest under P- and lowest under C- stress. Underlying these phenotypic changes was differential gene expression of terminal oxidases used for ATP generation that allows for increased energy generation efficiency. In all treatments under fast dilution rates, KT2440 formed aggregates and biofilms, a physiological response that hindered an accurate assessment of growth rate, but which could serve as a mechanism that allows cells to remain in conditions where growth is favorable. Our findings highlight the ways that microorganisms dynamically adjust their physiology under different resource supply conditions, with distinct mechanisms depending on the limiting resource at slow growth and convergence toward an aggregative phenotype with similar compositions under conditions that attempt to force fast growth. IMPORTANCE: All organisms experience suboptimal growth conditions due to low nutrient and energy availability. Their ability to survive and reproduce under such conditions determines their evolutionary fitness. By imposing suboptimal resource ratios under different dilution rates on the model organism Pseudomonas putida KT2440, we show that this bacterium dynamically adjusts its elemental composition, morphology, pools of biomolecules, and levels of gene expression. By examining the ability of bacteria to respond to C:N:P imbalance, we can begin to understand how stoichiometric flexibility manifests at the cellular level and impacts the flow of energy and elements through ecosystems.

Associations between urine specific gravity and race/ethnicity at the population level: Implications for hydration status categorization.

OBJECTIVE: We aimed to evaluate how urine specific gravity (USG) and rates of supposed hypohydration vary by race/ethnicity, and to examine how adjustment for several important factors impacts estimated USG. METHODS: Using the National Health and Nutrition Examination Survey, this cross-sectional study evaluated a total of 4195 (2098 female, 2097 male) Americans and categorized them as supposedly hypohydrated (USG≥1.020) or not using spot urine samples. USG and prevalence of supposed hypohydration were compared across racial/ethnic groups, separately by gender. The analyses considered the impact of urine creatinine, body composition, age, dietary nutrients, and physical activity. RESULTS: Differences in supposed hypohydration prevalence were observed by race/ethnicity in men (p = .030) and women (p < .001). In unadjusted models, Black women's USG (1.0189) was higher (p < .05) than all the other race/ethnicity groups' USG (1.0142-1.0171). In men, Blacks' USG (1.0197) was higher (p < .05) than the USG of Whites (1.0177) and other/multi-racial (1.0176) but not Mexican Americans (1.0196) or other Hispanics (1.0192). Adjustments for age, arm circumference, nutrients (protein, sodium, potassium, and moisture), and physical activity minimally influenced USG estimates. Further adjustment for urine creatinine lowered USG for Black women and men by 0.003 and 0.0023, respectively, with no notable lowering of USG in the other races/ethnicities. Supplemental analyses matching Whites and Blacks on age, moisture intake, and poverty-to-income ratio confirmed racial differences in urine creatinine and USG, though the effects were most pronounced in women. CONCLUSIONS: Using a USG≥1.020 to identify hypohydration in all races/ethnicities may be inappropriate due to, among other factors, differences in urinary creatinine.

A µ-opioid receptor modulator that works cooperatively with naloxone.

The µ-opioid receptor (µOR) is a well-established target for analgesia1, yet conventional opioid receptor agonists cause serious adverse effects, notably addiction and respiratory depression. These factors have contributed to the current opioid overdose epidemic driven by fentanyl2, a highly potent synthetic opioid. µOR negative allosteric modulators (NAMs) may serve as useful tools in preventing opioid overdose deaths, but promising chemical scaffolds remain elusive. Here we screened a large DNA-encoded chemical library against inactive µOR, counter-screening with active, G-protein and agonist-bound receptor to 'steer' hits towards conformationally selective modulators. We discovered a NAM compound with high and selective enrichment to inactive µOR that enhances the affinity of the key opioid overdose reversal molecule, naloxone. The NAM works cooperatively with naloxone to potently block opioid agonist signalling. Using cryogenic electron microscopy, we demonstrate that the NAM accomplishes this effect by binding a site on the extracellular vestibule in direct contact with naloxone while stabilizing a distinct inactive conformation of the extracellular portions of the second and seventh transmembrane helices. The NAM alters orthosteric ligand kinetics in therapeutically desirable ways and works cooperatively with low doses of naloxone to effectively inhibit various morphine-induced and fentanyl-induced behavioural effects in vivo while minimizing withdrawal behaviours. Our results provide detailed structural insights into the mechanism of negative allosteric modulation of the µOR and demonstrate how this can be exploited in vivo.

The impact of Library Size and Scale of Testing on Virtual Screening.

Virtual libraries for ligand discovery have recently increased 10,000-fold, and this is thought to have improved hit rates and potencies from library docking. This idea has not, however, been experimentally tested in direct comparisons of larger-vs-smaller libraries. Meanwhile, though libraries have exploded, the scale of experimental testing has little changed, with often only dozens of high-ranked molecules investigated, making interpretation of hit rates and affinities uncertain. Accordingly, we docked a 1.7 billion molecule virtual library against the model enzyme AmpC ß-lactamase, testing 1,521 new molecules and comparing the results to the same screen with a library of 99 million molecules, where only 44 molecules were tested. Encouragingly, the larger screen outperformed the smaller one: hit rates improved by two-fold, more new scaffolds were discovered, and potency improved. Overall, 50-fold more inhibitors were found, supporting the idea that there are many more compounds to be discovered than are being tested. With so many compounds evaluated, we could ask how the results vary with number tested, sampling smaller sets at random from the 1521. Hit rates and affinities were highly variable when we only sampled dozens of molecules, and it was only when we included several hundred molecules that results converged. As docking scores improved, so too did the likelihood of a molecule binding; hit rates improved steadily with docking score, as did affinities. This also appeared true on reanalysis of large-scale results against the σ2 and dopamine D4 receptors. It may be that as the scale of both the virtual libraries and their testing grows, not only are better ligands found but so too does our ability to rank them.

Development of a Cell-Based Reporter Potency Assay for Live Virus Vaccines.

The rapid development of potency assays is critical in the development of life-saving vaccines. The traditional plaque assay or fifty percent tissue culture infectious dose (TCID50) assay used to measure the potency of live virus vaccines is time consuming, labor intensive, low throughput and with high variability. Described here is the development and qualification of a cell-based reporter potency assay for two vaccines for respiratory viral infection, one based on the recombinant vesicular stomatitis virus (rVSV) backbone, termed Vaccine 1 in this paper, and the other based on the measles virus vector, termed Vaccine 2. The reporter potency assay used a Vero E6 cell line engineered to constitutively express NanuLuc® luciferase, termed the VeroE6-NLuc or JM-1 cell line. Infection of JM-1 cells by a live virus, such as rVSV or measles virus, causes a cytopathic effect (CPE) and release of NanuLuc® from the cytoplasm into the supernatant, the amount of which reflects the intensity of the viral infection. The relative potency was calculated by comparison to a reference standard using parallel line analysis (PLA) in a log-log linear model. The reporter assay demonstrated good linearity, accuracy, and precision, and is therefore suitable for a vaccine potency assay. Further evaluation of the Vaccine 1 reporter assay demonstrated the robustness to a range of deliberate variation of the selected assay parameters and correlation with the plaque assay. In conclusion, we have demonstrated that the reporter assay using the JM-1 cell line could be used as a potency assay to support the manufacturing and release of multiple live virus vaccines.

Surgical prophylaxis in pancreatoduodenectomy: Is cephalosporin still the drug of choice in patients with biliary stents in situ?

BACKGROUND: Universal surgical prophylaxis for pancreatoduodenectomy (PD) is practiced, with cephalosporins recommended in most guidelines. Recent studies suggest piperacillin-tazobactam (PTZ) prophylaxis in biliary-stented patients is superior in preventing surgical site infections (SSIs). This study aims to refine surgical prophylaxis recommendations based on the local microbial profile and evaluate the clinical outcomes of biliary-stented compared with non-stented patients. METHODS: This was a retrospective study of all consecutive PD patients at Singapore General Hospital between January 2013 to December 2019. The primary outcome was post-operative SSI rates. Secondary outcomes included rates of ceftriaxone-resistant Klebsiella pneumoniae, Escherichia coli, and Enterococcus species from intraoperative bile cultures and 30-day mortality. RESULTS: There were 130 biliary-stented and 211 non-stented patients included. Majority of biliary-stented patients received ceftriaxone ± metronidazole prophylaxis (83/130, 63.8 %) while 30/130 (23.8 %) received PTZ. Most non-stented patients received ceftriaxone ± metronidazole prophylaxis (163/211, 77.3 %). Between biliary-stented and non-stented patients, post-operative SSIs (40.8 % vs 38.4 %, p = 0.662), and 30-day mortality rates (1.5 % vs 1.4 %, p = 1.000) were comparable. The adjusted odds of post-operative SSIs was significantly lower in biliary-stented patients prescribed PTZ as compared to non-PTZ prophylaxis (0.29, 95 % CI (0.10-0.79), p = 0.015). Ceftriaxone-resistant Klebsiella spp. and/or Escherichia coli (27.6 % vs 3.8 %, p < 0.001) as well as Enterococcus species (46.1 % vs 11.5 %, p < 0.001), were more prevalent in intraoperative bile cultures of biliary-stented patients, while frequencies in non-stented patients were low. CONCLUSION: PTZ prophylaxis effectively reduced SSIs in stented patients post-pancreatoduodenectomy. Based on the local microbial profile, ceftriaxone prophylaxis may be used for prophylaxis in non-stented patients.

Late-life dietary folate restriction reduces biosynthesis without compromising healthspan in mice.

Folate is a vitamin required for cell growth and is present in fortified foods in the form of folic acid to prevent congenital abnormalities. The impact of low-folate status on life-long health is poorly understood. We found that limiting folate levels with the folate antagonist methotrexate increased the lifespan of yeast and worms. We then restricted folate intake in aged mice and measured various health metrics, metabolites, and gene expression signatures. Limiting folate intake decreased anabolic biosynthetic processes in mice and enhanced metabolic plasticity. Despite reduced serum folate levels in mice with limited folic acid intake, these animals maintained their weight and adiposity late in life, and we did not observe adverse health outcomes. These results argue that the effectiveness of folate dietary interventions may vary depending on an individual's age and sex. A higher folate intake is advantageous during the early stages of life to support cell divisions needed for proper development. However, a lower folate intake later in life may result in healthier aging.

Identifying Artifacts from Large Library Docking.

While large library docking has discovered potent ligands for multiple targets, as the libraries have grown, the very top of the hit-lists can become populated with artifacts that cheat our scoring functions. Though these cheating molecules are rare, they become ever-more dominant with library growth. Here, we investigate rescoring top-ranked molecules from docking screens with orthogonal methods to identify these artifacts, exploring implicit solvent models and absolute binding free energy perturbation (AB-FEP) as cross-filters. In retrospective studies, this approach deprioritized high-ranking non-binders for nine targets while leaving true ligands relatively unaffected. We tested the method prospectively against results from large library docking AmpC ß-lactamase. From the very top of the docking hit lists, we prioritized 128 molecules for synthesis and experimental testing, a mixture of 39 molecules that rescoring flagged as likely cheaters and another 89 that were plausible true actives. None of the 39 predicted cheating compounds inhibited AmpC up to 200µM in enzyme assays, while 57% of the 89 plausible true actives did do so, with 19 of them inhibiting the enzyme with apparent K i values better than 50µM. As our libraries continue to grow, a strategy of catching docking artifacts by rescoring with orthogonal methods may find wide use in the field.

Gas and particle emissions from rifle and pistol firing.

Emissions were sampled from firing an M4 carbine rifle and a M9 (military issue of Beretta 75 FS 9 mm pistol) to develop sampling methods and assess potential exposures and range contamination issues. Breech and muzzle emissions were sampled from the rifle when firing M855A1 ammunition (lead (Pb)-free slugs) in single- and triple-shot burst mode and from single pistol shots when firing 9 mm XM1152 ammunition (not Pb-free). Emissions were sampled for carbon monoxide (CO), carbon dioxide (CO2), methane, hydrogen cyanide, ammonia, particulate matter by size, polycylic aromatic hydrocarbons, and volatile organics. Analyses on the particles included elemental composition, size distribution, carbon composition (black, total, organic, and elemental carbon), and particle composition and morphology. Emission concentrations from both the rifle and pistol were characterized by CO/CO2 ratios between, approximately, 1/1 and 2/1, respectfully, indicating incomplete carbon oxidation. The initial particle size distribution was dominated in number by particles smaller than 40 nm but the high particle concentrations led to rapid agglomeration. The abundance of CO and metals of inhalable particle size are noteworthy and indicate that further assessment of exposure would determine potential inhalation health hazards, particularly in indoor firing ranges.

Instructional Influencers: Teaching Professors as Potential Departmental Change Agents in Diversity, Equity, and Inclusion.

At many research-intensive universities in North America, there is a disproportionate loss of minoritized undergraduate students from Science, Technology, Engineering, and Mathematics (STEM) majors. Efforts to confront this diversity, equity, and inclusion (DEI) challenge, such as faculty adoption of evidenced-based instructional approaches that promote student success, have been slow. Instructional and pedagogical change efforts at the academic department level have been demonstrated to be effective at enacting reform. One potential strategy is to embed change agent individuals within STEM departments that can drive change efforts. This study seeks to assess whether tenure-track, teaching-focused faculty housed in STEM departments are perceived as influential on the instructional and pedagogical domains of their colleagues. To answer this, individuals across five STEM departments at large, research-intensive campuses identified faculty who were influential upon six domains of their instruction and pedagogy. Social network analysis of individuals in these departments revealed heterogeneity across the instructional domains. Some, like the teaching strategies network, are highly connected and involve the majority of the department; while others, like the DEI influence network, comprise a significantly smaller population of faculty. Importantly, we demonstrate that tenure-track, teaching-focused faculty are influential across all domains of instruction, but are disproportionately so in the sparsely populated DEI influence networks.