The hemodynamic interplay between pulmonary ischemia-reperfusion injury and right ventricular function in lung transplantation: a translational porcine model.

Lung transplantation (LTx) is a challenging procedure. Following the process of ischemia-reperfusion injury, the transplanted pulmonary graft might become severely damaged, resulting in primary graft dysfunction. In addition, during the intraoperative window, the right ventricle (RV) is at risk of acute failure. The interaction of right ventricular function with lung injury is, however, poorly understood. We aimed to address this interaction in a translational porcine model of pulmonary ischemia-reperfusion injury. Advanced pulmonary and hemodynamic assessment was used, including right ventricular pressure-volume loop analysis. The acute model was based on clamping and unclamping of the left lung hilus, respecting the different hemodynamic phases of a clinical lung transplantation. We found that forcing entire right ventricular cardiac output through a lung suffering from ischemia-reperfusion injury increased afterload (pulmonary vascular resistance from baseline to end experiment P < 0.0001) and induced right ventricular failure (RVF) in 5/9 animals. Notably, we identified different compensation patterns in failing versus nonfailing ventricles (arterial elastance P = 0.0008; stroke volume P < 0.0001). Furthermore, increased vascular pressure and flow produced by the right ventricle resulted in higher pulmonary injury, as measured by ex vivo CT density (correlation: pressure r = 0.8; flow r = 0.85). Finally, RV ischemia as measured by troponin-T was negatively correlated with pulmonary injury (r = -0.76); however, troponin-T values did not determine RVF in all animals. In conclusion, we demonstrate a delicate balance between development of pulmonary ischemia-reperfusion injury and right ventricular function during lung transplantation. Furthermore, we provide a physiological basis for potential benefit of extracorporeal life support technology.NEW & NOTEWORTHY In contrast to the abundant literature of mechanical pulmonary artery clamping to increase right ventricular afterload, we developed a model adding a biological factor of pulmonary ischemia-reperfusion injury. We did not only focus on the right ventricular behavior, but also on the interaction with the injured lung. We are the first to describe this interaction while addressing the hemodynamic intraoperative phases of clinical lung transplantation.

Lung transplantation for acute respiratory distress syndrome: A multicenter experience.

Acute respiratory distress syndrome (ARDS) is a rapidly progressive lung disease with a high mortality rate. Although lung transplantation (LTx) is a well-established treatment for a variety of chronic pulmonary diseases, LTx for acute lung failure (due to ARDS) remains controversial. We reviewed posttransplant outcome of ARDS patients from three high-volume European transplant centers. Demographics and clinical data were collected and analyzed. Viral infection was the main reason for ARDS (n = 7/13, 53.8%). All patients were admitted to ICU and required mechanical ventilation, 11/13 were supported with ECMO at the time of listing. They were granted a median LAS of 76 (IQR 50-85) and waited for a median of 3 days (IQR 1.5-14). Postoperatively, median length of mechanical ventilation was 33 days (IQR 17-52.5), median length of ICU and hospital stay were 39 days (IQR 19.5-58.5) and 54 days (IQR 43.5-127). Prolongation of peripheral postoperative ECMO was required in 7/13 (53.8%) patients with a median duration of 2 days (IQR 2-7). 30-day mortality was 7.7%, 1 and 5-year survival rates were calculated as 71.6% and 54.2%, respectively. Given the lack of alternative treatment options, the herein presented results support the concept of offering live-saving LTx to carefully selected ARDS patients.

Shiga Toxin-Producing Escherichia coli Infections Associated With Romaine Lettuce-United States, 2018.

BACKGROUND: Produce-associated outbreaks of Shiga toxin-producing Escherichia coli (STEC) were first identified in 1991. In April 2018, New Jersey and Pennsylvania officials reported a cluster of STEC O157 infections associated with multiple locations of a restaurant chain. The Centers for Disease Control and Prevention (CDC) queried PulseNet, the national laboratory network for foodborne disease surveillance, for additional cases and began a national investigation. METHODS: A case was defined as an infection between 13 March and 22 August 2018 with 1 of the 22 identified outbreak-associated E. coli O157:H7 or E. coli O61 pulsed-field gel electrophoresis pattern combinations, or with a strain STEC O157 that was closely related to the main outbreak strain by whole-genome sequencing. We conducted epidemiologic and traceback investigations to identify illness subclusters and common sources. A US Food and Drug Administration-led environmental assessment, which tested water, soil, manure, compost, and scat samples, was conducted to evaluate potential sources of STEC contamination. RESULTS: We identified 240 case-patients from 37 states; 104 were hospitalized, 28 developed hemolytic uremic syndrome, and 5 died. Of 179 people who were interviewed, 152 (85%) reported consuming romaine lettuce in the week before illness onset. Twenty subclusters were identified. Product traceback from subcluster restaurants identified numerous romaine lettuce distributors and growers; all lettuce originated from the Yuma growing region. Water samples collected from an irrigation canal in the region yielded the outbreak strain of STEC O157. CONCLUSIONS: We report on the largest multistate leafy greens-linked STEC O157 outbreak in several decades. The investigation highlights the complexities associated with investigating outbreaks involving widespread environmental contamination.

Histopathologic and radiologic assessment of nontransplanted donor lungs.

Donor organ shortage results in significant waiting list mortality. Donor lung assessment is currently based on donors' history, gas exchange, chest X-ray, bronchoscopy findings, and ultimately in situ inspection but remains subjective. We correlated histopathology and radiology in nontransplanted donor lungs with the clinical indications to decline the offered organ. Sixty-two donor lungs, not used for transplantation (2010-2019), were procured, air-inflated, frozen, scanned with computed tomography, systematically sampled, and histologically and radiologically assessed. Thirty-nine (63%) lungs were declined for allograft-related reasons. In 13/39 (33%) lungs, histology could not confirm the reason for decline, in an additional 8/39 (21%) lungs, histologic abnormalities were only considered mild. In 16/39 (41%) lungs, radiology could not confirm the reason for decline. Twenty-three (37%) donor lungs were not transplanted due to extrapulmonary causes, of which three (13%) lungs displayed severe histologic abnormalities (pneumonia, n = 2; emphysema, n = 1), in addition to mild emphysema in 9 (39%) lungs and minor bronchopneumonia in 1 (4%). Radiology revealed ground-glass opacities in 8/23 (35%) and emphysema in 4/23 (17%) lungs. Histopathologic and radiologic assessment of nontransplanted donor lungs revealed substantial discrepancy with the clinical reason for decline. Optimization of donor lung assessment is necessary to improve current organ acceptance rates.

Risk for Invasive Streptococcal Infections among Adults Experiencing Homelessness, Anchorage, Alaska, USA, 2002-2015.

The risk for invasive streptococcal infection has not been clearly quantified among persons experiencing homelessness (PEH). We compared the incidence of detected cases of invasive group A Streptococcus infection, group B Streptococcus infection, and Streptococcus pneumoniae (pneumococcal) infection among PEH with that among the general population in Anchorage, Alaska, USA, during 2002-2015. We used data from the Centers for Disease Control and Prevention's Arctic Investigations Program surveillance system, the US Census, and the Anchorage Point-in-Time count (a yearly census of PEH). We detected a disproportionately high incidence of invasive streptococcal disease in Anchorage among PEH. Compared with the general population, PEH were 53.3 times as likely to have invasive group A Streptococcus infection, 6.9 times as likely to have invasive group B Streptococcus infection, and 36.3 times as likely to have invasive pneumococcal infection. Infection control in shelters, pneumococcal vaccination, and infection monitoring could help protect the health of this vulnerable group.

Prone Positioning During Ex Vivo Lung Perfusion Influences Regional Edema Accumulation.

BACKGROUND: Ex vivo lung perfusion (EVLP) is developed to increase the quantity and quality of suitable grafts for lung transplantation. Standardly, lungs are mounted supine with the risk of fluid accumulation in the dorsal regions. Therefore, we investigated the impact of experimental prone position on graft function during EVLP. MATERIALS AND METHODS: Porcine lungs were mounted on a normothermic EVLP for 6 h in supine [S], (n = 7) or prone position [P], (n = 7). Physiology during EVLP was recorded. After EVLP, biopsies were assessed for wet-to-dry weight (W/D) ratios and pathology, broncho-alveolar lavage was measured, and the left lung was computed tomography (CT) scanned. RESULTS: Physiological parameters were similar between both groups, despite a higher pulmonary vascular resistance in [P] (P = 0.0002). In [S], W/D ratios and CT density of dorsal areas were higher compared to ventral (P = 0.0017 and P = 0.053, respectively). In [P], W/D and CT density between ventral and dorsal regions were similar, meaning that pulmonary edema was distributed more homogeneously throughout the lung. Histology and cytokine levels in perfusate and broncho-alveolar lavage did not differ between both groups. CONCLUSIONS: Prone positioning during EVLP is feasible and leads to more homogenous distribution of interstitial fluid. Supine position resulted in more concentrated edema accumulation in lower dependent regions.

Risk Factors for Group A Streptococcus Colonization During an Outbreak Among People Experiencing Homelessness in Anchorage, Alaska, 2017.

We identified risk factors for any emm type group A streptococcal (GAS) colonization while investigating an invasive emm26.3 GAS outbreak among people experiencing homelessness in Alaska. Risk factors included upper extremity skin breakdown, sleeping outdoors, sharing blankets, and infrequent tooth brushing. Our results may help guide control efforts in future outbreaks.

Outbreak of Invasive Infections From Subtype emm26.3 Group A Streptococcus Among Homeless Adults-Anchorage, Alaska, 2016-2017.

Background: In 2016, we detected an outbreak of group A Streptococcus (GAS) invasive infections among the estimated 1000 persons experiencing homelessness (PEH) in Anchorage, Alaska. We characterized the outbreak and implemented a mass antibiotic intervention at homeless service facilities. Methods: We identified cases through the Alaska GAS laboratory-based surveillance system. We conducted emm typing, antimicrobial susceptibility testing, and whole-genome sequencing on all invasive isolates and compared medical record data of patients infected with emm26.3 and other emm types. In February 2017, we offered PEH at 6 facilities in Anchorage a single dose of 1 g of azithromycin. We collected oropharyngeal and nonintact skin swabs on a subset of participants concurrent with the intervention and 4 weeks afterward. Results: From July 2016 through April 2017, we detected 42 invasive emm26.3 cases in Anchorage, 35 of which were in PEH. The emm26.3 isolates differed on average by only 2 single-nucleotide polymorphisms. Compared to other emm types, infection with emm26.3 was associated with cellulitis (odds ratio [OR], 2.5; P = .04) and necrotizing fasciitis (OR, 4.4; P = .02). We dispensed antibiotics to 391 PEH. Colonization with emm26.3 decreased from 4% of 277 at baseline to 1% of 287 at follow-up (P = .05). Invasive GAS incidence decreased from 1.5 cases per 1000 PEH/week in the 6 weeks prior to the intervention to 0.2 cases per 1000 PEH/week in the 6 weeks after (P = .01). Conclusions: In an invasive GAS outbreak in PEH in Anchorage, mass antibiotic administration was temporally associated with reduced invasive disease cases and colonization prevalence.

X-ray structure of human aquaporin 2 and its implications for nephrogenic diabetes insipidus and trafficking.

Human aquaporin 2 (AQP2) is a water channel found in the kidney collecting duct, where it plays a key role in concentrating urine. Water reabsorption is regulated by AQP2 trafficking between intracellular storage vesicles and the apical membrane. This process is tightly controlled by the pituitary hormone arginine vasopressin and defective trafficking results in nephrogenic diabetes insipidus (NDI). Here we present the X-ray structure of human AQP2 at 2.75 Å resolution. The C terminus of AQP2 displays multiple conformations with the C-terminal α-helix of one protomer interacting with the cytoplasmic surface of a symmetry-related AQP2 molecule, suggesting potential protein-protein interactions involved in cellular sorting of AQP2. Two Cd(2+)-ion binding sites are observed within the AQP2 tetramer, inducing a rearrangement of loop D, which facilitates this interaction. The locations of several NDI-causing mutations can be observed in the AQP2 structure, primarily situated within transmembrane domains and the majority of which cause misfolding and ER retention. These observations provide a framework for understanding why mutations in AQP2 cause NDI as well as structural insights into AQP2 interactions that may govern its trafficking.

Power and persuasion in the vaccine debates: an analysis of political efforts and outcomes in the United States, 1998-2012.

CONTEXT: This article examines trends in state-level childhood vaccine policies in the United States from 1998 to 2012 and explains the trajectories for both vaccine-critical and proimmunization legislative efforts. Successful mobilization by vaccine critics during the height of the autism and thimerosal scares (roughly 1998 to 2003) yielded a few state-level expansions for the most permissive type of exemption from vaccine mandates for public school attendance, those based on personal beliefs. Vaccine-critical positions, however, have largely become discredited. How has vaccine critics' ability to advance preferred policies and prevent the passage of unfavorable legislation changed over time? METHODS: We created a unique data set of childhood vaccine bills (n = 636), introduced from 1998 to 2012 across the 50 state legislatures, and coded them by type of effort (exemption, mandate, mercury ban, and information policies) and outcome. We then mapped out the trends in vaccine policies over time. In order to contextualize the trends we identified, we also reviewed numerous primary sources and conducted interviews with stakeholders. FINDINGS: In general, we found that vaccine critics' legislative success has begun to wane. In only 20 bills in our data set were vaccine critics able to change policy in their preferred direction via the legislative process. Only 5 of those wins were significant (such as obtaining a new philosophical exemption to vaccine mandates), and the last of these was in 2007. Critics were more successful at preventing passage of proimmunization legislation, such as mandates for the human papillomavirus (HPV) vaccine. CONCLUSIONS: Recent legislation in California, Oregon, and Washington that tightened philosophical exemptions by means of informational requirements suggests that vaccine politics may be entering another phase, one in which immunization supporters may be able to counter increasing opt-out rates, particularly in states with recent outbreaks and politicians favoring science-based policies.

Mercury increases water permeability of a plant aquaporin through a non-cysteine-related mechanism.

Water transport across cellular membranes is mediated by a family of membrane proteins known as AQPs (aquaporins). AQPs were first discovered on the basis of their ability to be inhibited by mercurial compounds, an experiment which has followed the AQP field ever since. Although mercury inhibition is most common, many AQPs are mercury insensitive. In plants, regulation of AQPs is important in order to cope with environmental changes. Plant plasma membrane AQPs are known to be gated by phosphorylation, pH and Ca²âº. We have previously solved the structure of the spinach AQP SoPIP2;1 (Spinacia oleracea plasma membrane intrinsic protein 2;1) in closed and open conformations and proposed a mechanism for how this gating can be achieved. To study the effect of mercury on SoPIP2;1 we solved the structure of the SoPIP2;1-mercury complex and characterized the water transport ability using proteoliposomes. The structure revealed mercury binding to three out of four cysteine residues. In contrast to what is normally seen for AQPs, mercury increased the water transport rate of SoPIP2;1, an effect which could not be attributed to any of the cysteine residues. This indicates that other factors might influence the effect of mercury on SoPIP2;1, one of which could be the properties of the lipid bilayer.

Computed tomography-based machine learning for donor lung screening before transplantation.

BACKGROUND: Assessment and selection of donor lungs remain largely subjective and experience based. Criteria to accept or decline lungs are poorly standardized and are not compliant with the current donor pool. Using ex vivo computed tomography (CT) images, we investigated the use of a CT-based machine learning algorithm for screening donor lungs before transplantation. METHODS: Clinical measures and ex situ CT scans were collected from 100 cases as part of a prospective clinical trial. Following procurement, donor lungs were inflated, placed on ice according to routine clinical practice, and imaged using a clinical CT scanner before transplantation while stored in the icebox. We trained and tested a supervised machine learning method called dictionary learning, which uses CT scans and learns specific image patterns and features pertaining to each class for a classification task. The results were evaluated with donor and recipient clinical measures. RESULTS: Of the 100 lung pairs donated, 70 were considered acceptable for transplantation (based on standard clinical assessment) before CT screening and were consequently implanted. The remaining 30 pairs were screened but not transplanted. Our machine learning algorithm was able to detect pulmonary abnormalities on the CT scans. Among the patients who received donor lungs, our algorithm identified recipients who had extended stays in the intensive care unit and were at 19 times higher risk of developing chronic lung allograft dysfunction within 2 years posttransplant. CONCLUSIONS: We have created a strategy to ex vivo screen donor lungs using a CT-based machine learning algorithm. As the use of suboptimal donor lungs rises, it is important to have in place objective techniques that will assist physicians in accurately screening donor lungs to identify recipients most at risk of posttransplant complications.

The nature of chronic rejection after lung transplantation: a murine orthotopic lung transplant study.

Introduction: Chronic rejection is a major complication post-transplantation. Within lung transplantation, chronic rejection was considered as airway centred. Chronic Lung Allograft Dysfunction (CLAD), defined to cover all late chronic complications, makes it more difficult to understand chronic rejection from an immunological perspective. This study investigated the true nature, timing and location of chronic rejection as a whole, within mouse lung transplantation. Methods: 40 mice underwent an orthotopic left lung transplantation, were sacrificed at day 70 and evaluated by histology and in vivo µCT. For timing and location of rejection, extra grafts were sacrificed at day 7, 35, 56 and investigated by ex vivo µCT or single cell RNA (scRNA) profiling. Results: Chronic rejection originated as innate inflammation around small arteries evolving toward adaptive organization with subsequent end-arterial fibrosis and obliterans. Subsequently, venous and pleural infiltration appeared, followed by airway related bronchiolar folding and rarely bronchiolitis obliterans was observed. Ex vivo µCT and scRNA profiling validated the time, location and sequence of events with endothelial destruction and activation as primary onset. Conclusion: Against the current belief, chronic rejection in lung transplantation may start as an arterial response, followed by responses in venules, pleura, and, only in the late stage, bronchioles, as may be seen in some but not all patients with CLAD.

Structural and functional analysis of aquaporin-2 mutants involved in nephrogenic diabetes insipidus.

Aquaporins are water channels found in the cell membrane, where they allow the passage of water molecules in and out of the cells. In the kidney collecting duct, arginine vasopressin-dependent trafficking of aquaporin-2 (AQP2) fine-tunes reabsorption of water from pre-urine, allowing precise regulation of the final urine volume. Point mutations in the gene for AQP2 may disturb this process and lead to nephrogenic diabetes insipidus (NDI), whereby patients void large volumes of highly hypo-osmotic urine. In recessive NDI, mutants of AQP2 are retained in the endoplasmic reticulum due to misfolding. Here we describe the structural and functional characterization of three AQP2 mutations associated with recessive NDI: T125M and T126M, situated close to a glycosylation site and A147T in the transmembrane region. Using a proteoliposome assay, we show that all three mutants permit the transport of water. The crystal structures of T125M and T126M together with biophysical characterization of all three mutants support that they retain the native structure, but that there is a significant destabilization of A147T. Our work provides unique molecular insights into the mechanisms behind recessive NDI as well as deepens our understanding of how misfolded proteins are recognized by the ER quality control system.

The Effect of Prone Positioning After Lung Transplantation.

BACKGROUND: Prone positioning has become a standard therapy in acute respiratory distress syndrome to improve oxygenation and decrease mortality. However, little is known about prone positioning in lung transplant recipients. This large, singe-center analysis investigated whether prone positioning improves gas exchange after lung transplantation. METHODS: Clinical data of 583 patients were analyzed. Prone position was considered in case of impaired gas exchange Pao2/fraction of oxygen in inhaled air (<250), signs of edema after lung transplantation, and/or evidence of reperfusion injury. Patients with hemodynamic instability or active bleeding were not proned. Impact of prone positioning (n = 165) on gas exchange, early outcome and survival were determined and compared with patients in supine positioning (n = 418). RESULTS: Patients in prone position were younger, more likely to have interstitial lung disease, and had a higher lung allocation score. Patients were proned for a median of 19 hours (interquartile range,15-26) hours). They had significantly lower Pao2/fraction of oxygen in inhaled air (227 ± 96 vs 303 ± 127 mm Hg, P = .004), and lower lung compliance (24.8 ± 9.1 mL/mbar vs 29.8 ± 9.7 mL/mbar, P < .001) immediately after lung transplantation. Both values significantly improved after prone positioning for 24 hours (Pao2/fraction of oxygen ratio: 331 ± 91 mm Hg; lung compliance: 31.7 ± 20.2 mL/mbar). Survival at 90 days was similar between the 2 groups (93% vs 96%, P = .105). CONCLUSIONS: Prone positioning led to a significant improvement in lung compliance and oxygenation after lung transplantation. Prospective studies are needed to confirm the benefit of prone positioning in lung transplantation.

CT-based Machine Learning for Donor Lung Screening Prior to Transplantation.

Background: Assessment and selection of donor lungs remains largely subjective and experience based. Criteria to accept or decline lungs are poorly standardized and are not compliant with the current donor pool. Using ex vivo CT images, we investigated the use of a CT-based machine learning algorithm for screening donor lungs prior to transplantation. Methods: Clinical measures and ex-situ CT scans were collected from 100 cases as part of a prospective clinical trial. Following procurement, donor lungs were inflated, placed on ice according to routine clinical practice, and imaged using a clinical CT scanner prior to transplantation while stored in the icebox. We trained and tested a supervised machine learning method called dictionary learning , which uses CT scans and learns specific image patterns and features pertaining to each class for a classification task. The results were evaluated with donor and recipient clinical measures. Results: Of the 100 lung pairs donated, 70 were considered acceptable for transplantation (based on standard clinical assessment) prior to CT screening and were consequently implanted. The remaining 30 pairs were screened but not transplanted. Our machine learning algorithm was able to detect pulmonary abnormalities on the CT scans. Among the patients who received donor lungs, our algorithm identified recipients who had extended stays in the ICU and were at 19 times higher risk of developing CLAD within 2 years post-transplant. Conclusions: We have created a strategy to ex vivo screen donor lungs using a CT-based machine learning algorithm. As the use of suboptimal donor lungs rises, it is important to have in place objective techniques that will assist physicians in accurately screening donor lungs to identify recipients most at risk of post-transplant complications.

Difficulties in the differential diagnosis of large solitary pulmonary cysts.

Large solitary cystic lesions are a rare finding, and their differential diagnosis includes cystic airspaces associated with lung cancer, congenital pulmonary airway malformations and pneumatoceles. Here, we report 3 consecutive patients who presented with a large solitary pulmonary cyst on chest computed tomography. All underwent surgical resection, and the histopathological findings were different in all 3 cases. In one patient, a very rare finding of squamous cell carcinoma arising from the cystic lesion in the left lower lobe was confirmed. Therefore, in carefully selected cases, pulmonary cysts should be resected based on the potential risk for recurrent infection and the development of malignancy.

Functional outcome after single-stage laryngotracheal reconstruction with rib cartilage grafting.

OBJECTIVE: Single-stage laryngotracheal reconstruction (SSLTR) provides a definite surgical treatment for patients with complex glotto-subglottic stenosis. To date, the influence of SSLTR on the functional outcome after surgery has not been analyzed. METHODS: A retrospective analysis of all patients receiving a SSLTR between November 2012 and October 2019 was performed. Preoperatively and 3 months postoperatively, patients received a full functional evaluation, including spirometry; voice measurements (eg, fundamental frequency; dynamic range, singing voice range, and perceptual voice evaluation using the Roughness-Breathiness-Hoarseness [RBH] score, and fiberoptic endoscopic evaluation of swallowing [FEES]). RESULTS: A total of 15 patients with a mean age of 45 ± 17 years underwent SSTLR. Two (13%) patients were men and 13 (87%) were women. The majority of patients (67%) had undergone previous surgical or endoscopic treatment attempts that had failed. At the 3-month follow-up visit, none of the patients had signs of penetration or aspiration in their swallowing examination. Voice measurements revealed a significantly lower fundamental voice frequency (201.0 Hz vs 155.5 Hz; P = .006), whereas voice range (19.1 semitones vs 14.9 semitones; P = .200) and dynamic range (52.5 dB vs 53.0 dB; P = .777) was hardly affected. The median RBH score changed from R1 B0 H1 to R2 B1 H2. In spirometry, breathing capacity increased significantly (peak expiratory flow, 44% vs 87% [P < .001] and mean expiratory flow at 75% of vital capacity, 48% vs 90% [P < .001]). During a median follow-up of 32.5 months (range, 7-88 months), none of the patients developed re-stenosis. CONCLUSIONS: For complex glotto-subglottic stenoses, durable long-term airway patency together with reasonable voice quality and normal deglutition can be achieved by SSLTR.