Faculty Bibliography

The in vitro activity of sulopenem was assessed against a 2014-2016 collection of 539 urinary isolates of Escherichia coli from Canadian patients using CLSI-defined broth microdilution methodology. A concentration of sulopenem of 0.03 µg/ml inhibited both 50% (MIC₅₀) and 90% (MIC₉₀) of isolates tested; sulopenem MICs ranged from 0.015 to 0.25 µg/ml. The in vitro activity of sulopenem was unaffected by non-susceptibility to trimethoprim-sulfamethoxazole and/or ciprofloxacin, multidrug-resistant (MDR) phenotypes, extended-spectrum β-lactamases (ESBLs), or AmpC β-lactamases.

Cyanotic heart lesions are a complex subset of congenital heart disease (CHD) in which patients are desaturated until surgical repair or palliation. We hypothesized that a direct relationship would exist between degree of desaturation and presence of systemic inflammation and brain injury in unrepaired patients less than 1 year of age. The pre-operative desaturation with augmented systemic inflammation would predict a more complex post-operative course. Fifty patients with CHD were enrolled in this study and classified as cyanotic (O₂ ≤ 90%) or acyanotic (O₂ > 90%) based on SpO₂. Serum inflammatory mediators measured included interleukins (IL)-6, IL-8, IL-12p70, IL-10, IL-1β, tumor necrosis factor (TNF)-α, interferon (INF)-γ; macrophage inhibitory factor (MIF) and a novel brain biomarker, phosphorylated neurofilament heavy subunit (pNF-H). Twenty-two cyanotic and 28 acyanotic subjects were enrolled with SpO₂ of 78 ± 18% and 98 ± 2% (p < 0.001), respectively, and mean age of 72 days (range 2-303) and 102 days (range 1-274), respectively. Cyanotic vs acyanotic subjects had elevated serum IL-6 (6.6 ± 7.6 vs 2.9 ± 2.9 pg/ml, p = 0.019) and pNF-H (222 ± 637 vs 57 ± 121 pg/ml, p = 0.046), and both biomarkers correlated with degree of desaturation (Spearman rank-order correlation ρ = - 0.30, p = 0.037 and ρ = - 0.29 p = 0.049, respectively). Post-operative inotrope scores at 24 h and duration of mechanical ventilation correlated inversely with pre-operative oxygen saturation (ρ = - 0.380, p = 0.014 and ρ = - 0.362, p = 0.020, respectively). The degree of pre-operative desaturation correlated with a more complicated post-operative course supporting the need for advanced peri-operative therapy in this population.

The physiological consequences of the unfolded protein response (UPR) are mediated by changes in gene expression. Underlying them are rapid processes involving preexisting components. We review recent insights gained into the regulation of the endoplasmic reticulum (ER) Hsp70 chaperone BiP, whose incorporation into inactive oligomers and reversible AMPylation and de-AMPylation present a first line of response to fluctuating levels of unfolded proteins. BiP activity is tied to the regulation of the UPR transducers by a recently discovered cycle of ER-localized, J-protein-mediated formation of a repressive IRE1-BiP complex, whose working we contrast to an alternative model for UPR regulation that relies on direct recognition of unfolded proteins. We conclude with a discussion of mechanisms that repress messenger RNA (mRNA) translation to limit the flux of newly synthesized proteins into the ER, a rapid adaptation that does not rely on new macromolecule biosynthesis.

Although bone marrow-derived mesenchymal stem cells (BM-MSCs) are widely recognized as promising therapeutic agents, the age-related impacts on cellular function remain largely uncharacterized. In this study, we found that BM-MSCs from young donors healed wounds in a xenograft model faster compared with their aged counterparts (p < .001). Given this significant healing advantage, we then used single-cell transcriptomic analysis to provide potential molecular insights into these observations. We found that the young cells contained a higher proportion of cells characterized by a higher expression of genes involved in tissue regeneration. In addition, we identified a unique, quiescent subpopulation that was exclusively present in young donor cells. Together, these findings may explain a novel mechanism for the enhanced healing capacity of young stem cells and may have implications for autologous cell therapy in the extremes of age. Stem Cells 2018.

A striking observation among veterans returning from the recent conflicts in Iraq and Afghanistan has been the co-occurrence of blast-related mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD). PTSD and mTBI might coexist due to additive effects of independent psychological and physical traumas experienced in a war zone. Alternatively blast injury might induce PTSD-related traits or damage brain structures that mediate responses to psychological stressors, increasing the likelihood that PTSD will develop following a subsequent psychological stressor. Rats exposed to repetitive low-level blasts consisting of three 74.5 kilopascal exposures delivered once daily for three consecutive days develop a variety of anxiety and PTSD-related behavioral traits that are present for at least 9 months after blast exposure. A single predator scent challenge delivered 8 months after the last blast exposure induces additional anxiety-related changes that are still present 45 days later. Because the blast injuries occur under general anesthesia, it appears that blast exposure in the absence of a psychological stressor can induce chronic PTSD-related traits. The reaction to a predator scent challenge delivered many months after blast exposure suggests that blast exposure in addition sensitizes the brain to react abnormally to subsequent psychological stressors. The development of PTSD-behavioral related traits in the absence of a psychological stressor suggests the existence of blast-induced "PTSD". Findings that PTSD-related behavioral traits can be reversed by BCI-838, a group II metabotropic glutamate receptor antagonist offers insight into pathogenesis and possible treatment options for blast-related brain injury.

Stable isotope labeling by amino acids in cell culture (SILAC) has become very popular as a quantitative proteomic method since it was firstly introduced by Matthias Mann's group in 2002. It is a metabolic labeling strategy in which isotope-labeled amino acids are metabolically incorporated in vivo into proteins during translation. After natural (light) or heavy amino acid incorporation, differentially labeled samples are mixed immediately after cell lysis and before any further processing, which minimizes quantitative errors caused by handling different samples in parallel. In this unit, we describe protocols for basic duplex SILAC, triplex SILAC for use in nondividing cells such as neurons, and for measuring amounts of newly synthesized proteins. © 2018 by John Wiley & Sons, Inc.

PURPOSE/OBJECTIVE:Schools undergoing curricular reform are reconsidering the optimal timing of Step 1. This study provides a psychometric investigation of the impact on United States Medical Licensing Examination Step 1 scores of changing the timing of Step 1 from after completion of the basic science curricula to after core clerkships. METHOD/METHODS:Data from four schools that recently moved the examination were analyzed in a pre-post format using examinee scores from three years before and after the change. The sample included scores from 2008 through 2016. Several confounders were addressed, including rising national scores and potential differences in cohort abilities using deviation scores and analysis of covariance (ANCOVA) controlling for Medical College Admission Test (MCAT) scores. A resampling procedure compared study schools' score changes to similar schools' in the same time period. RESULTS:The ANCOVA indicated that post-change Step 1 scores were higher compared to pre-change (adjusted difference = 2.67, 95% confidence interval [CI]: 1.50-3.83, P < .001; effect size = 0.14) after adjusting for MCAT scores and rising national averages. The average score increase in the study schools was larger than changes seen in similar schools. Failure rates also decreased from 2.87% (n = 48) pre-change to 0.39% (n = 6) post-change (P < .001). CONCLUSIONS:Results suggest moving Step 1 after core clerkships yielded a small increase in scores and a reduction in failure rates. While these small increases are unlikely to represent meaningful knowledge gains, this demonstration of "non-inferiority" may allow schools to implement significant curricular reformsWritten work prepared by employees of the Federal Government as part of their official duties is, under the U.S. Copyright Act, a "work of the United States Government" for which copyright protection under Title 17 of the United States Code is not available. As such, copyright does not extend to the contributions of employees of the Federal Government.

The many steps of gene expression, from the transcription of a gene to the production of its protein product, are well understood. Yet, transcriptional regulation has been the focal point for the study of gene expression during development. However, quantitative studies reveal that messenger RNA (mRNA) levels are not necessarily good predictors of the respective proteins' levels in a cell. This discrepancy is, at least in part, the result of developmentally regulated, translational mechanisms that control the spatiotemporal regulation of gene expression. In this review, we focus on translational regulatory mechanisms mediating global transitions in gene expression: the shift from the maternal to the embryonic developmental program in the early embryo and the switch from the self-renewal of stem cells to differentiation in the adult.

Chronic inflammation drives many obesity-associated conditions, including atherosclerosis. GlycA, a marker of systemic inflammation with lower intraindividual variability than hsCRP, is independently associated with incident cardiovascular events and mortality. Although GlycA is elevated in obesity, correlations with anthropometric measures are modest and the effect of weight loss on GlycA is untested. Obese (BMI 44.6±6.6kg/m² ), non-diabetic women (33.7±8.2 years) undergoing Roux-en-Y gastric bypass (n=23) or sleeve gastrectomy (n=31) were prospectively studied at baseline, 6 and 12 months post-procedure. Women with normal BMI (n=14) served as controls. Bariatric surgery significantly reduced GlycA by 6 months (451±47umol/L vs 383±50umol/L; p<0.001) with further reduction at 12 months (348±41umol/L; p<0.001) and no difference between procedures. At 12 months, despite 41% of surgical subjects maintaining BMI >30kg/m² , GlycA levels did not differ between surgical and control subjects (p=0.13). Increased HDL particle size was strongly associated with reduced GlycA (r=-0.49; p<0.001) and was found to mediate up to 43% of its weight-loss-associated fall. This is the first study to demonstrate that surgical weight loss markedly reduces levels of GlycA.

Over the past two decades, considerable advances in our understanding of inflammatory and immune pathways have allowed for the growing use of targeted biologic therapy. Most notably, the introduction of tumor necrosis factor (TNF) inhibitors has dramatically changed the management of autoimmune inflammatory disorders, including ankylosing spondylitis (AS). Despite the efficacy of TNF inhibitors documented in multiple clinical trials, anti-TNF therapy in AS is far from foolproof; it is associated with serious adverse effects and limited response to therapy in some patients. Moreover, specific questions regarding the role of TNF as a mediator of AS remain unanswered. Therefore, additional efforts are needed in order to better understand the role of TNF in the pathogenesis of AS and to develop safer and more effective treatment strategies. The purpose of this review is to better the understanding of the physiologic and pathogenic roles of TNF signaling in the course of AS. Relevant TNF biology and novel approaches to TNF blockade in AS are discussed.