Microbial thermogenesis is dependent on ATP concentrations and the protein kinases ArcB, GlnL, and YccC.

Organisms necessarily release heat energy in their pursuit of survival. This process is known as cellular thermogenesis and is implicated in many processes from cancer metabolism to spontaneous farm fires. However, the molecular basis for this fundamental phenomenon is yet to be elucidated. Here, we show that the major players involved in the cellular thermogenesis of Escherichia coli are the protein kinases ArcB, GlnL, and YccC. We also reveal the substrate-level control of adenosine triphosphate (ATP)-driven autophosphorylation that governs cellular thermogenesis. Specifically, through live cell microcalorimetry, we find these regulatory proteins, when knocked out in a model E. coli strain, dysregulate cellular thermogenesis. This dysregulation can be seen in an average 25% or greater increase in heat output by these cells. We also discover that both heat output and intracellular ATP levels are maximal during the late log phase of growth. Additionally, we show that microbial thermogenesis can be engineered through overexpressing glnL. Our results demonstrate a correlation between ATP concentrations in the cell and a cell's ability to generate excess heat. We expect this work to be the foundation for engineering thermogenically tuned organisms for a variety of applications.

Implementation of a direct-to-operating room aortic emergency transfer program: Expedited management of type A aortic dissection.

INTRODUCTION: Type A Aortic Dissection (TAAD) is a surgical emergency with a time-dependent rate of mortality. We hypothesized that a direct-to-operating room (DOR) transfer program for patients with TAAD would reduce time to intervention. METHODS: A DOR program was started at an urban tertiary care hospital in February 2020. We performed a retrospective study of adult patients undergoing treatment for TAAD before (n = 42) and after (n = 84) implementation of DOR. Expected mortality was calculated using the International Registry of Acute Aortic Dissection risk prediction model. RESULTS: Median time from acceptance of transfer from emergency physician to operating room arrival was 1.37 h (82 min) faster in DOR compared to pre-DOR (1.93 h vs 3.30 h, p < 0.001). Median time from arrival to operating room was 1.14 h (72 min) faster after DOR compared to pre-DOR (0.17 h vs 1.31 h, p < 0.001). In-hospital mortality was 16.2% in pre-DOR, with an observed-to-expected (O/E) ratio of 1.03 (p = 0.24) and 12.0% in the DOR group, with an O/E ratio of 0.59 (p < 0.001). CONCLUSION: Creation of a DOR program resulted in decreased time to intervention. This was associated with a decrease in observed-to-expected operative mortality. The transfer of patients with acute type A aortic dissection to centers with direct-to-OR programs may result in decreased time from diagnosis to surgery.

Differences in referral to a chronic thromboembolic pulmonary hypertension center following acute pulmonary embolism: a locoregional experience.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a treatable complication of acute pulmonary embolism (PE). Identification of factors that impact referral to a comprehensive CTEPH center may improve disease awareness and patient outcomes. We conducted a study of patients with acute PE. Cases were identified through a natural language processing algorithm. ICD coding was used to assess clinical documentation for dyspnea or CTEPH placed at least 90 days after their acute PE diagnosis. We analyzed characteristics of patients who were referred vs. not referred, as well as referral patterns for "at risk" patients. 2454 patients with acute PE were identified, of which 4.9% (120/2454) were referred for CTEPH evaluation. Patients who were not referred were older (61 vs. 54 years, p < 0.001), had higher rates of cancer (28% vs. 10%, p < 0.001), and lived further from the referral center (9.1 miles vs. 6.7 miles, p = 0.03). Of 175 patients identified as "at risk," 12% (21/175) were referred. In the 'at risk' cohort, distance from referral center among referred and not referred was significant (5.7 miles vs. 8.8 miles, p = 0.04). There were low rates of referral to CTEPH center in post-PE patients, and in patients with symptoms who may be at higher risk of CTEPH. Age, co-morbid conditions, distance from comprehensive center, and presence of a primary care provider contribute to differences in referral to a comprehensive CTEPH center. Clinician education about CTEPH is important to ensure optimal care to patients with or at risk for chronic complications of acute PE.

Residual endotoxin induces primary graft dysfunction through ischemia/reperfusion-primed alveolar macrophages.

Despite the widespread use of antibiotics, bacterial pneumonias in donors strongly predispose to the fatal syndrome of primary graft dysfunction (PGD) following lung transplantation. We report that bacterial endotoxin persists in human donor lungs after pathogen is cleared with antibiotics and is associated with neutrophil infiltration and PGD. In mouse models, depletion of tissue-resident alveolar macrophages (TRAMs) attenuated neutrophil recruitment in response to endotoxin as shown by compartmental staining and intravital imaging. Bone marrow chimeric mice revealed that neutrophils were recruited by TRAM through activation of TLR4 in a MyD88-dependent manner. Intriguingly, low levels of endotoxin, insufficient to cause donor lung injury, promoted TRAM-dependent production of CXCL2, increased neutrophil recruitment, and led to PGD, which was independent of donor NCMs. Reactive oxygen species (ROS) increased in human donor lungs starting from the warm-ischemia phase and were associated with increased transcription and translocation to the plasma membrane of TLR4 in donor TRAMs. Consistently, scavenging ROS or inhibiting their production to prevent TLR4 transcription/translocation or blockade of TLR4 or coreceptor CD14 on donor TRAMs prevented neutrophil recruitment in response to endotoxin and ameliorated PGD. Our studies demonstrate that residual endotoxin after successful treatment of donor bacterial pneumonia promotes PGD through ischemia/reperfusion-primed donor TRAMs.

Courtesy Authorship in Academic Surgery Publications.

Importance: Courtesy authorship is defined as including an individual who has not met authorship criteria as an author. Although most journals follow strict authorship criteria, the current incidence of courtesy authorship is unknown. Objective: To assess the practices related to courtesy authorship in surgical journals and academia. Design, Setting, and Participants: A survey was conducted from July 15 to October 27, 2017, of the first authors and senior authors of original articles, reviews, and clinical trials published between 2014 and 2015 in 8 surgical journals categorized as having a high or low impact factor. Main Outcomes and Measures: The prevalence of courtesy authorship overall and among subgroups of authors in high impact factor journals and low impact factor journals and among first authors and senior authors, as well as author opinions regarding courtesy authorship. Results: A total of 203 first authors and 254 senior authors responded (of 369 respondents who provided data on sex, 271 were men and 98 were women), with most being in academic programs (first authors, 116 of 168 [69.0%]; senior authors, 173 of 202 [85.6%]). A total of 17.2% of respondents (42 of 244) reported adding courtesy authors for the surveyed publications: 20.4% by first authors (32 of 157) and 11.5% by senior authors (10 of 87), but 53.7% (131 of 244) reported adding courtesy authorship on prior publications and 33.2% (81 of 244) had been added as a courtesy author in the past. Although 45 of 85 senior authors (52.9%) thought that courtesy authorship has decreased, 93 of 144 first authors (64.6%) thought that courtesy authorship has not changed or had increased (P = .03). There was no difference in the incidence of courtesy authorship for low vs high impact factor journals. Both first authors (29 of 149 [19.5%]) and senior authors (19 of 85 [22.4%]) reported pressures to add courtesy authorship, but external pressure was greater for low impact factor journals than for high impact factor journals (77 of 166 [46.4%] vs 60 of 167 [35.9%]; P = .04). More authors in low impact factor journals than in high impact factor journals thought that courtesy authorship was less harmful to academia (55 of 114 [48.2%] vs 34 of 117 [29.1%]). Overall, senior authors reported more positive outcomes with courtesy authorship (eg, improved morale and avoided author conflicts) than did first authors. Conclusions and Relevance: Courtesy authorship use is common by both first and senior authors in low impact factor journals and high impact factor journals. There are different perceptions, practices, and pressures to include courtesy authorship for first and senior authors. Understanding these issues will lead to better education to eliminate this practice.

Metformin Targets Mitochondrial Electron Transport to Reduce Air-Pollution-Induced Thrombosis.

Urban particulate matter air pollution induces the release of pro-inflammatory cytokines including interleukin-6 (IL-6) from alveolar macrophages, resulting in an increase in thrombosis. Here, we report that metformin provides protection in this murine model. Treatment of mice with metformin or exposure of murine or human alveolar macrophages to metformin prevented the particulate matter-induced generation of complex III mitochondrial reactive oxygen species, which were necessary for the opening of calcium release-activated channels (CRAC) and release of IL-6. Targeted genetic deletion of electron transport or CRAC channels in alveolar macrophages in mice prevented particulate matter-induced acceleration of arterial thrombosis. These findings suggest metformin as a potential therapy to prevent some of the premature deaths attributable to air pollution exposure worldwide.

Single-Cell Transcriptomic Analysis of Human Lung Provides Insights into the Pathobiology of Pulmonary Fibrosis.

Rationale: The contributions of diverse cell populations in the human lung to pulmonary fibrosis pathogenesis are poorly understood. Single-cell RNA sequencing can reveal changes within individual cell populations during pulmonary fibrosis that are important for disease pathogenesis. Objectives: To determine whether single-cell RNA sequencing can reveal disease-related heterogeneity within alveolar macrophages, epithelial cells, or other cell types in lung tissue from subjects with pulmonary fibrosis compared with control subjects. Methods: We performed single-cell RNA sequencing on lung tissue obtained from eight transplant donors and eight recipients with pulmonary fibrosis and on one bronchoscopic cryobiospy sample from a patient with idiopathic pulmonary fibrosis. We validated these data using in situ RNA hybridization, immunohistochemistry, and bulk RNA-sequencing on flow-sorted cells from 22 additional subjects. Measurements and Main Results: We identified a distinct, novel population of profibrotic alveolar macrophages exclusively in patients with fibrosis. Within epithelial cells, the expression of genes involved in Wnt secretion and response was restricted to nonoverlapping cells. We identified rare cell populations including airway stem cells and senescent cells emerging during pulmonary fibrosis. We developed a web-based tool to explore these data. Conclusions: We generated a single-cell atlas of pulmonary fibrosis. Using this atlas, we demonstrated heterogeneity within alveolar macrophages and epithelial cells from subjects with pulmonary fibrosis. These results support the feasibility of discovery-based approaches using next-generation sequencing technologies to identify signaling pathways for targeting in the development of personalized therapies for patients with pulmonary fibrosis.

Spleen-derived classical monocytes mediate lung ischemia-reperfusion injury through IL-1ß.

Ischemia-reperfusion injury, a form of sterile inflammation, is the leading risk factor for both short-term mortality following pulmonary transplantation and chronic lung allograft dysfunction. While it is well recognized that neutrophils are critical mediators of acute lung injury, processes that guide their entry into pulmonary tissue are not well understood. Here, we found that CCR2+ classical monocytes are necessary and sufficient for mediating extravasation of neutrophils into pulmonary tissue during ischemia-reperfusion injury following hilar clamping or lung transplantation. The classical monocytes were mobilized from the host spleen, and splenectomy attenuated the recruitment of classical monocytes as well as the entry of neutrophils into injured lung tissue, which was associated with improved graft function. Neutrophil extravasation was mediated by MyD88-dependent IL-1ß production by graft-infiltrating classical monocytes, which downregulated the expression of the tight junction-associated protein ZO-2 in pulmonary vascular endothelial cells. Thus, we have uncovered a crucial role for classical monocytes, mobilized from the spleen, in mediating neutrophil extravasation, with potential implications for targeting of recipient classical monocytes to ameliorate pulmonary ischemia-reperfusion injury in the clinic.

Humoral Human Lung Allograft Rejection by Tissue-Restricted Non-HLA Antibodies.

A third of lung recipients have preexisting antibodies against nonhuman leukocyte self-antigens (nHAbs) present in the lung tissue. These nHAbs also form de novo in about 70% of patients within 3 years after transplantation. Both preexisting and de novo nHAbs can cause murine lung allograft dysfunction. However, their role in human transplantation remains unclear. We report hyperacute rejection after right lung transplant in a recipient with preexisting nHAbs. The recipient of the left lung from the same donor had an uneventful initial course, but de novo nHAbs developed at 3 weeks, leading to acute humoral rejection. Both patients were successfully treated with antibody-directed therapies.

Lung Injury Combined with Loss of Regulatory T Cells Leads to De Novo Lung-Restricted Autoimmunity.

More than one third of patients with chronic lung disease undergoing lung transplantation have pre-existing Abs against lung-restricted self-Ags, collagen type V (ColV), and k-α1 tubulin (KAT). These Abs can also develop de novo after lung transplantation and mediate allograft rejection. However, the mechanisms leading to lung-restricted autoimmunity remain unknown. Because these self-Ags are normally sequestered, tissue injury is required to expose them to the immune system. We previously showed that respiratory viruses can induce apoptosis in CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs), the key mediators of self-tolerance. Therefore, we hypothesized that lung-tissue injury can lead to lung-restricted immunity if it occurs in a setting when Tregs are impaired. We found that human lung recipients who suffer respiratory viral infections experienced a decrease in peripheral Tregs. Pre-existing lung allograft injury from donor-directed Abs or gastroesophageal reflux led to new ColV and KAT Abs post respiratory viral infection. Similarly, murine parainfluenza (Sendai) respiratory viral infection caused a decrease in Tregs. Intratracheal instillation of anti-MHC class I Abs, but not isotype control, followed by murine Sendai virus infection led to development of Abs against ColV and KAT, but not collagen type II (ColII), a cartilaginous protein. This was associated with expansion of IFN-γ-producing CD4(+) T cells specific to ColV and KAT, but not ColII. Intratracheal anti-MHC class I Abs or hydrochloric acid in Foxp3-DTR mice induced ColV and KAT, but not ColII, immunity, only if Tregs were depleted using diphtheria toxin. We conclude that tissue injury combined with loss of Tregs can lead to lung-tissue-restricted immunity.

Role of monocytes and macrophages in regulating immune response following lung transplantation.

PURPOSE OF REVIEW: Advances in the field of monocyte and macrophage biology have dramatically changed our understanding of their role during homeostasis and inflammation. Here we review the role of these important innate immune effectors in the lung during inflammatory challenges including lung transplantation. RECENT FINDINGS: Neutrophil extravasation into lung tissue and the alveolar space have been shown to be pathogenic during acute lung injury as well as primary graft dysfunction following lung transplantation. Recent advances in lung immunology have demonstrated the remarkable plasticity of both monocytes and macrophages and demonstrated their importance as mediators of neutrophil recruitment and transendothelial migration during inflammation. SUMMARY: Monocytes and macrophages are emerging as key players in mediating both the pathogen response and sterile lung inflammation, including that arising from barotrauma and ischemia-reperfusion injury. Ongoing studies will establish the mechanisms by which these monocytes and macrophages initiate a variety of immune response that lay the fundamental basis of injury response in the lung.

Decreased CXCL12 is associated with impaired alveolar epithelial cell migration and poor lung healing after lung resection.

BACKGROUND: Prolonged air leak (PAL) is an important cause of morbidity and mortality after lung resection, but its pathogenesis has not been elucidated. Migration of alveolar type II epithelial cells is essential for lung wound repair. Here we determined the role of C-X-C motif chemokine 12 (CXCL12) on alveolar epithelial cell migration and lung wound healing. METHODS: CXCL12 in the pleural fluid of patients was analyzed using enzyme-linked immunosorbent assay. Human A549 and murine MLE12 alveolar epithelial cell lines were used for wound closure, cell migration, and proliferation assays. Western blot was used to analyze Rac1 and cofilin. RESULTS: Pleural CXCL12 was decreased in patients with PAL (1,389 ± 192 vs 3,270 ± 247 pg/mL; P < .0001). CXCL12 enhanced scratch wound closure in both A549 (77.9 ± 0.7% vs 71.5 ± 0.4%; P = .0016) and MLE12 (92.9 ± 4.9% vs 66.0 ± 4.8%; P = .017). CXCL12 enhanced migration by 57% in A549 (P = .0008) and by 86% in MLE12 (P < .0001). AMD3100, a selective CXCR4 antagonist, prevented the effects of CXCL12. CXCL12 increased Rac1 and cofilin activation but did not change bromodeoxyuridine incorporation or cell counts. CONCLUSION: Reduced pleural CXCL12 is associated with PAL. CXCL12 promotes alveolar epithelial cell migration by binding to its receptor CXCR4 and may have a role in lung healing. CXCL12-mediated alveolar epithelial cell migration is associated with Rac1 and cofilin activation.

A comparison of the GlideScope video laryngoscope to the C-MAC video laryngoscope for intubation in the emergency department.

STUDY OBJECTIVE: There is growing use of video laryngoscopy in US emergency departments (EDs). This study seeks to compare intubation success between the GlideScope video laryngoscope and the C-MAC video laryngoscope (C-MAC) in ED intubations. METHODS: This was an analysis of quality improvement data collected during a 3-year period in an academic ED. After each intubation, the operator completed a standardized data form reporting patient demographics, indication for intubation, device(s) used, reason for device selection, difficult airway characteristics, number of attempts, and outcome of each attempt. An attempt was defined as insertion of the device into the mouth regardless of attempt at tube placement. The primary outcomes were first pass and overall intubation success. The study compared success rates between the GlideScope video laryngoscope and the C-MAC groups, using multivariable logistic regression and adjusting for potential confounders. RESULTS: During the 3-year study period, there were 463 intubations, including 230 with the GlideScope video laryngoscope as the initial device and 233 with the C-MAC as the initial device. The GlideScope video laryngoscope resulted in first-pass success in 189 of 230 intubations (82.2%; 95% confidence interval [CI] 76.6% to 86.9%) and overall success in 221 of 230 intubations (96.1%; 95% CI 92.7% to 98.2%). The C-MAC resulted in first-pass success in 196 of 233 intubations (84.1%; 95% CI 78.8% to 88.6%) and overall success in 225 of 233 intubations (96.6%; 95% CI 93.4% to 98.5%). In a multivariate logistic regression analysis, the type of video laryngoscopic device was not associated with first-pass (odds ratio 1.1; 95% CI 0.6 to 2.1) or overall success (odds ratio 1.2; 95% CI 0.5 to 3.1). CONCLUSION: In this study of video laryngoscopy in the ED, the GlideScope video laryngoscope and the C-MAC were associated with similar rates of intubation success.

A comparison of the C-MAC video laryngoscope to the Macintosh direct laryngoscope for intubation in the emergency department.

STUDY OBJECTIVE: We determine the proportion of successful intubations with the C-MAC video laryngoscope (C-MAC) compared with the direct laryngoscope in emergency department (ED) intubations. METHODS: This was a retrospective analysis of prospectively collected data entered into a continuous quality improvement database during a 28-month period in an academic ED. After each intubation, the operator completed a standardized data form evaluating multiple aspects of the intubation, including patient demographics, indication for intubation, device(s) used, reason for device selection, difficult airway characteristics, number of attempts, and outcome of each attempt. Intubation was considered ultimately successful if the endotracheal tube was correctly inserted into the trachea with the initial device. An attempt was defined as insertion of the device into the mouth regardless of whether there was an attempt to pass the tube. The primary outcome measure was ultimate success. Secondary outcome measures were first-attempt success, Cormack-Lehane view, and esophageal intubation. Multivariate logistic regression analyses, with the inclusion of a propensity score, were performed for the outcome variables ultimate success and first-attempt success. RESULTS: During the 28-month study period, 750 intubations were performed with either the C-MAC with a size 3 or 4 blade or a direct laryngoscope with a Macintosh size 3 or 4 blade. Of these, 255 were performed with the C-MAC as the initial device and 495 with a Macintosh direct laryngoscope as the initial device. The C-MAC resulted in successful intubation in 248 of 255 cases (97.3%; 95% confidence interval [CI] 94.4% to 98.9%). A direct laryngoscope resulted in successful intubation in 418 of 495 cases (84.4%; 95% CI 81.0% to 87.5%). In the multivariate regression model, with a propensity score included, the C-MAC was positively predictive of ultimate success (odds ratio 12.7; 95% CI 4.1 to 38.8) and first-attempt success (odds ratio 2.2; 95% CI 1.2 to 3.8). When the C-MAC was used as a video laryngoscope, a Cormack-Lehane grade I or II view (video) was obtained in 117 of 125 cases (93.6%; 95% CI 87.8% to 97.2%), whereas when a direct laryngoscope was used, a grade I or II view was obtained in 410 of 495 cases (82.8%; 95% CI 79.2% to 86.1%). The C-MAC was associated with immediately recognized esophageal intubation in 4 of 255 cases (1.6%; 95% CI 0.4% to 4.0%), whereas a direct laryngoscope was associated with immediately recognized esophageal intubation in 24 of 495 cases (4.8%; 95% CI 3.1% to 7.1%). CONCLUSION: When used for emergency intubations in the ED, the C-MAC was associated with a greater proportion of successful intubations and a greater proportion of Cormack-Lehane grade I or II views compared with a direct laryngoscope.

Difficult airway management in the emergency department: GlideScope videolaryngoscopy compared to direct laryngoscopy.

BACKGROUND: Videolaryngoscopy has become a popular method of intubation in the Emergency Department (ED), however, little research has compared this technique with direct laryngoscopy (DL). OBJECTIVE: To compare the success rates of GlideScope (Verathon Inc., Bothell, WA) videolaryngoscopy (GVL) and DL in emergent airways with known difficult airway predictors (DAPs). METHODS: We evaluated 772 consecutive ED intubations over a 23-month period. After each intubation, the physician completed a data collection form that included: demographics, DAPs, Cormack-Lehane view, optical clarity, lens contamination, and complications. DAPs included: cervical immobility, obesity, small mandible, large tongue, short neck, blood or vomit in the airway, tracheal edema, secretions, and facial or neck trauma. Primary outcome was first-attempt success rates. Multivariate logistic regression was performed to evaluate the odds of failure for DL compared to GVL. RESULTS: First-attempt success rate with DL was 68%, GVL 78% (Fisher's exact test, p = 0.001). Adjusted odds of success of GVL compared to DL on first attempt equals 2.20 (odds ratio [OR] 2.2, 95% confidence interval [CI] 1.51-3.19). After statistically controlling for DAPs, GVL was more likely to succeed on first attempt than DL (OR 3.07, 95% CI 2.19-4.30). Logistic regression of DAPs showed that the presence of blood, small mandible, obesity, and a large tongue were statistically significant risk factors for decreasing the odds of success with DL and increasing the odds of success of GVL. CONCLUSION: For difficult airways with the presence of blood or small mandible, or a large tongue or obesity, GVL had a higher success rate at first attempt than DL.

Tracheal intubation in the emergency department: a comparison of GlideScope® video laryngoscopy to direct laryngoscopy in 822 intubations.

BACKGROUND: Video laryngoscopy has, in recent years, become more available to emergency physicians. However, little research has been conducted to compare their success to conventional direct laryngoscopy. OBJECTIVES: To compare the success rates of GlideScope(®) (Verathon Inc., Bothell, WA) videolaryngoscopy (GVL) with direct laryngoscopy (DL) for emergency department (ED) intubations. METHODS: This was a 24-month retrospective observational study of all patients intubated in a single academic ED with a level I trauma center. Structured data forms were completed after each intubation and entered into a continuous quality improvement database. All patients intubated in the ED with either the GlideScope(®) standard, Cobalt, Ranger, or traditional Macintosh or Miller laryngoscopes were included. All patients intubated before arrival were excluded. Primary analysis evaluated overall and first-attempt success rates, operator experience level, performance characteristics of GVL, complications, and reasons for failure. RESULTS: There were 943 patients intubated during the study period; 120 were excluded due to alternative management strategies. DL was used in 583 (62%) patients, and GVL in 360 (38%). GVL had higher first-attempt success (75%, p = 0.03); DL had a higher success rate when more than one attempt was required (57%, p = 0.003). The devices had statistically equivalent overall success rates. GVL had fewer esophageal intubations (n = 1) than DL (n = 18); p = 0.005. CONCLUSION: The two techniques performed equivalently overall, however, GVL had a higher overall success rate, and lower number of esophageal complications. In the setting of ED intubations, GVL offers an excellent option to maximize first-attempt success for airway management.