Development of an Algorithm to Screen for Frailty Using the Clinical Frailty Scale with Postoperative Patients Entering Cardiac Rehabilitation

Purpose

Frailty is not commonly assessed on intake to cardiac rehabilitation (CR), but screening could enable targeted interventions and potentially reduce secondary complications. This study aimed to develop and retrospectively examine the feasibility of utilizing a CR-specific algorithm based on the Clinical Frailty Scale (CFS). Our CFS-CR algorithm endeavoured to screen for frailty in older adults (> 65 y) entering CR following cardiac surgery/procedure.

Method

The charts of 30 former patients (mean age: 74.0 ± 6.9 y) were examined by a clinician working in CR.

Results

The clinician was unable to score any of the patients based on their medical charts using the CFS-CR due to insufficient data. Documentation was typically limited in the areas of instrumental and basic activities of daily living whereas exercise data were readily available.

Conclusions

Current intake documentation in CR limited the ability to retrospectively screen for frailty. This finding suggests a need for a frailty-specific tool to support routine clinical screening. Prospective evaluation of the CFS-CR is warranted to further examine the clinical utility of the algorithm during CR intake assessments.

The metagenome-derived esterase PET40 is highly promiscuous and hydrolyses polyethylene terephthalate (PET)

Polyethylene terephthalate (PET) is a widely used synthetic polymer and known to contaminate marine and terrestrial ecosystems. Only few PET-active microorganisms and enzymes (PETases) are currently known, and it is debated whether degradation activity for PET originates from promiscuous enzymes with broad substrate spectra that primarily act on natural polymers or other bulky substrates, or whether microorganisms evolved their genetic makeup to accepting PET as a carbon source. Here, we present a predicted diene lactone hydrolase designated PET40, which acts on a broad spectrum of substrates, including PET. It is the first esterase with activity on PET from a GC-rich Gram-positive Amycolatopsis species belonging to the Pseudonocardiaceae (Actinobacteria). It is highly conserved within the genera Amycolatopsis and Streptomyces. PET40 was identified by sequence-based metagenome search using a PETase-specific hidden Markov model. Besides acting on PET, PET40 has a versatile substrate spectrum, hydrolyzing δ-lactones, β-lactam antibiotics, the polyester-polyurethane Impranil® DLN, and various para-nitrophenyl ester substrates. Molecular docking suggests that the PET degradative activity is likely a result of the promiscuity of PET40, as potential binding modes were found for substrates encompassing mono(2-hydroxyethyl) terephthalate, bis(2-hydroxyethyl) terephthalate, and a PET trimer. We also solved the crystal structure of the inactive PET40 variant S178A to 1.60 Å resolution. PET40 is active throughout a wide pH (pH 4-10) and temperature range (4-65 °C) and remarkably stable in the presence of 5% SDS, making it a promising enzyme as a starting point for further investigations and optimization approaches.

External Validation of 8 Normal Tissue Complication Probability Models for Radiation-Associated Primary Hypothyroidism Using Long-Term Thyroid Function Outcomes

PURPOSE/OBJECTIVE(S)

Primary hypothyroidism is a common late complication following neck irradiation. The reported incidences were as high as 20-50% among head and neck cancer survivors. Several normal tissue complication probability models for radiation-associated primary hypothyroidism have been proposed, but none has been externally validated using long-term thyroid function outcome.

MATERIALS/METHODS

We undertook a systematic review of the literature and identified 8 distinct normal tissue complication probability (NTCP) models for radiation-associated primary hypothyroidism (6 logistic regression models and 2 nomograms). We retrospectively contoured and reviewed the thyroid gland dosimetry of all consecutive head and neck cancer patients who underwent definitive radiotherapy between January 2013 and December 2015 in two tertiary oncology centers. Patients with abnormal pre-radiotherapy thyroid function were excluded. Thyroid function was monitored at least yearly after radiotherapy. Primary hypothyroidism was defined as serum thyroid-stimulating hormone levels above the upper limit of normal. Euthyroid controls were defined as patients who had normal thyroid function at least 5 years beyond the completion of radiotherapy. Diagnostic properties (sensitivity, specificity and accuracy) of the 8 NTCP models were determined. Discrimination and calibration of the models were assessed using c-statistics, discrimination slopes, calibration curves and Brier score.

RESULTS

With a median follow-up of 7.0 years, we identified 216 cases of post-radiation primary hypothyroidism and 120 euthyroid controls within the study period. All four logistic regression models (Boomsma 2012, Rønjom 2013, Shen 2021 and Huang 2021) which were based on mean thyroid dose and thyroid volume demonstrated satisfactory diagnostic performances. The accuracy, c-statistic, discrimination slope and Brier score of these four models were > 0.70 (0.711 - 0.732), > 0.75 (0.763 - 0.765), > 0.20 (0.203 - 0.295) and < 0.20 (0.187 - 0.198), respectively. Calibrations of prediction were excellent at ranges of high predicted probabilities. At ranges of low predicted probabilities, these models underestimated the risk of primary hypothyroidism by 10-20%. Other models or nomograms which utilized alternative radiation dose-volume parameters (e.g., V30, V35 or V50), or without factoring in the variation in thyroid volume, had significantly worse performance in terms of both discrimination and calibration.

CONCLUSION

This large external validation study showed that NTCP models that included thyroid volume and mean thyroid dose had satisfactory performances in predicting long-term thyroid function outcomes following neck irradiation. Refinement is required to optimize calibration in patients deemed at low risk of post-radiation primary hypothyroidism.

An archaeal lid-containing feruloyl esterase degrades polyethylene terephthalate

Polyethylene terephthalate (PET) is a commodity polymer known to globally contaminate marine and terrestrial environments. Today, around 80 bacterial and fungal PET-active enzymes (PETases) are known, originating from four bacterial and two fungal phyla. In contrast, no archaeal enzyme had been identified to degrade PET. Here we report on the structural and biochemical characterization of PET46 (RLI42440.1), an archaeal promiscuous feruloyl esterase exhibiting degradation activity on semi-crystalline PET powder comparable to IsPETase and LCC (wildtypes), and higher activity on bis-, and mono-(2-hydroxyethyl) terephthalate (BHET and MHET). The enzyme, found by a sequence-based metagenome search, is derived from a non-cultivated, deep-sea Candidatus Bathyarchaeota archaeon. Biochemical characterization demonstrated that PET46 is a promiscuous, heat-adapted hydrolase. Its crystal structure was solved at a resolution of 1.71 Å. It shares the core alpha/beta-hydrolase fold with bacterial PETases, but contains a unique lid common in feruloyl esterases, which is involved in substrate binding. Thus, our study widens the currently known diversity of PET-hydrolyzing enzymes, by demonstrating PET depolymerization by a plant cell wall-degrading esterase.

Towards Sustainable Recycling of Epoxy-Based Polymers: Approaches and Challenges of Epoxy Biodegradation

Epoxy resins are highly valued for their remarkable mechanical and chemical properties and are extensively used in various applications such as coatings, adhesives, and fiber-reinforced composites in lightweight construction. Composites are especially important for the development and implementation of sustainable technologies such as wind power, energy-efficient aircrafts, and electric cars. Despite their advantages, their non-biodegradability raises challenges for the recycling of polymer and composites in particular. Conventional methods employed for epoxy recycling are characterized by their high energy consumption and the utilization of toxic chemicals, rendering them rather unsustainable. Recent progress has been made in the field of plastic biodegradation, which is considered more sustainable than energy-intensive mechanical or thermal recycling methods. However, the current successful approaches in plastic biodegradation are predominantly focused on polyester-based polymers, leaving more recalcitrant plastics underrepresented in this area of research. Epoxy polymers, characterized by their strong cross-linking and predominantly ether-based backbone, exhibit a highly rigid and durable structure, placing them within this category. Therefore, the objective of this review paper is to examine the various approaches that have been employed for the biodegradation of epoxy so far. Additionally, the paper sheds light on the analytical techniques utilized in the development of these recycling methods. Moreover, the review addresses the challenges and opportunities entailed in epoxy recycling through bio-based approaches.

A worldwide survey on perioperative antimicrobial prophylaxis for heart transplantation: From theory to clinical practice

BACKGROUND

The aim of our survey was to analyze the current attitudes toward antimicrobial prophylaxis in heart transplanting centers worldwide.

METHODS

The survey was composed of a total of 50 questions, it consisted of four different sections as follows. The first section collected physicians' personal data and centers' general characteristics, second assessed the approach to patients colonized with multidrug-resistant organisms (MDROs), while the third consisted of the infection risk related to cardiovascular devices, and antimicrobial treatment data, the last focused on donor's colonization.

RESULTS

A total of 56 answers from 26 different countries were collected, mostly from Europe (n = 30) and the USA (n = 16). A first-generation cephalosporin (58.9%) or a combination therapy with vancomycin (10.7%) were the most frequently prescribed antimicrobial prophylaxis. Roughly 30% of the centers used different antimicrobial prophylaxis,mostly including Gram negative bacteria coverage. The frequency of screening for multidrug resistant Gram-negative bacteria was higher in Europe, where the percentage of centers providing screening for extended spectrum beta-lactamase (46.7%) and carbapenem-resistant Enterobacteriaceae (CRE) (53.3%) was higher than in other geographic area (p = .019; p = .013, respectively).

CONCLUSION

This survey highlights a heterogeneity of clinical practice concerning antimicrobial prophylaxis at transplant. The concern for potential Gram-negative bacteria infection was responsible for broader antimicrobial coverage in 30% of centers.

The PET-Degrading Potential of Global Metagenomes: From In Silico Mining to Active Enzymes

Against the background of the steadily increasing amount of plastic waste in the sea and on land, it is more important than ever to find ways out of this situation. In recent years, microorganisms have been discovered that are capable of degrading artificial polymers such as polyethylene terephthalate (PET). Even if the turnover rates of the enzymes responsible for this reaction may be too low to solve the global plastic pollution problem, it is still of great societal interest to find microorganisms that are able to degrade the polymer. The corresponding enzymes, PET esterases (PETases) can be used in biotechnological processes and could contribute to a resource-saving circular economy. In this chapter, we present a sequence-based in silico screening method to find new PETases in metagenomic datasets. This method can easily be adapted to find other enzyme classes. We also list a number of assays that can be used to test the enzymes for activity on PET as well as other substrates.

Investigation of the halophilic PET hydrolase PET6 from Vibrio gazogenes

The handling of plastic waste and the associated ubiquitous occurrence of microplastic poses one of the biggest challenges of our time. Recent investigations of plastic degrading enzymes have opened new prospects for biological microplastic decomposition as well as recycling applications. For polyethylene terephthalate, in particular, several natural and engineered enzymes are known to have such promising properties. From a previous study that identified new PETase candidates by homology search, we chose the candidate PET6 from the globally distributed, halophilic organism Vibrio gazogenes for further investigation. By mapping the occurrence of Vibrios containing PET6 homologs we demonstrated their ubiquitous prevalence in the pangenome of several Vibrio strains. The biochemical characterization of PET6 showed that PET6 has a comparatively lower activity than other enzymes but also revealed a superior turnover at very high salt concentrations. The crystal structure of PET6 provides structural insights into this adaptation to saline environments. By grafting only a few beneficial mutations from other PET degrading enzymes onto PET6, we increased the activity up to three-fold, demonstrating the evolutionary potential of the enzyme. MD simulations of the variant helped rationalize the mutational effects of those mutants and elucidate the interaction of the enzyme with a PET substrate. With tremendous amounts of plastic waste in the Ocean and the prevalence of Vibrio gazogenes in marine biofilms and estuarine marshes, our findings suggest that Vibrio and the PET6 enzyme are worthy subjects to study the PET degradation in marine environments.

A novel metagenome-derived viral RNA polymerase and its application in a cell-free expression system for metagenome screening

The mining of genomes from non-cultivated microorganisms using metagenomics is a powerful tool to discover novel proteins and other valuable biomolecules. However, function-based metagenome searches are often limited by the time-consuming expression of the active proteins in various heterologous host systems. We here report the initial characterization of novel single-subunit bacteriophage RNA polymerase, EM1 RNAP, identified from a metagenome data set obtained from an elephant dung microbiome. EM1 RNAP and its promoter sequence are distantly related to T7 RNA polymerase. Using EM1 RNAP and a translation-competent Escherichia coli extract, we have developed an efficient medium-throughput pipeline and protocol allowing the expression of metagenome-derived genes and the production of proteins in cell-free system is sufficient for the initial testing of the predicted activities. Here, we have successfully identified and verified 12 enzymes acting on bis(2-hydroxyethyl) terephthalate (BHET) in a completely clone-free approach and proposed an in vitro high-throughput metagenomic screening method.

Microbial enzymes will offer limited solutions to the global plastic pollution crisis

Global economies depend on the use of fossil-fuel-based polymers with 360-400 million metric tons of synthetic polymers being produced per year. Unfortunately, an estimated 60% of the global production is disposed into the environment. Within this framework, microbiologists have tried to identify plastic-active enzymes over the past decade. Until now, this research has largely failed to deliver functional biocatalysts acting on the commodity polymers such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), ether-based polyurethane (PUR), polyamide (PA), polystyrene (PS) and synthetic rubber (SR). However, few enzymes are known to act on low-density and low-crystalline (amorphous) polyethylene terephthalate (PET) and ester-based PUR. These above-mentioned polymers represent >95% of all synthetic plastics produced. Therefore, the main challenge microbiologists are currently facing is in finding polymer-active enzymes targeting the majority of fossil-fuel-based plastics. However, identifying plastic-active enzymes either to implement them in biotechnological processes or to understand their potential role in nature is an emerging research field. The application of these enzymes is still in its infancy. Here, we summarize the current knowledge on microbial plastic-active enzymes, their global distribution and potential impact on plastic degradation in industrial processes and nature. We further outline major challenges in finding novel plastic-active enzymes, optimizing known ones by synthetic approaches and problems arising through falsely annotated and unfiltered use of database entries. Finally, we highlight potential biotechnological applications and possible re- and upcycling concepts using microorganisms.

Plastics degradation by hydrolytic enzymes: The plastics-active enzymes database-PAZy

Petroleum-based plastics are durable and accumulate in all ecological niches. Knowledge on enzymatic degradation is sparse. Today, less than 50 verified plastics-active enzymes are known. First examples of enzymes acting on the polymers polyethylene terephthalate (PET) and polyurethane (PUR) have been reported together with a detailed biochemical and structural description. Furthermore, very few polyamide (PA) oligomer active enzymes are known. In this article, the current known enzymes acting on the synthetic polymers PET and PUR are briefly summarized, their published activity data were collected and integrated into a comprehensive open access database. The Plastics-Active Enzymes Database (PAZy) represents an inventory of known and experimentally verified enzymes that act on synthetic fossil fuel-based polymers. Almost 3000 homologs of PET-active enzymes were identified by profile hidden Markov models. Over 2000 homologs of PUR-active enzymes were identified by BLAST. Based on multiple sequence alignments, conservation analysis identified the most conserved amino acids, and sequence motifs for PET- and PUR-active enzymes were derived.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

A226 SEX-BASED DISPARITY COMPLICATIONS FOLLOWING LIVER TRANSPLANTATION

Background

Sex-based disparity exists in liver transplantation (LT) with women being disadvantaged at every stage of the process starting from assessment to post transplantation (Bryce et al., 2009). The reasons for this are multifactorial and include biological disparities, psychosocial, and allocation inequalities (Burra et al., 2013).

Aims

The purpose of this study was to identify differences in immediate or long-term complications post-LT by sex.

Methods

We analyzed 702 patients who underwent LT at the University of Alberta from 2002 to 2015. Patients aged < 18 years or requiring a repeat or multivisceral transplant were excluded. Renal dysfunction was defined according to the KDIGO criteria. Cardiovascular disease (CVD) was defined as hospitalization for or death from coronary artery disease, cardiac arrest or cerebrovascular disease.

Results

Male patients comprised 69% of the population. Time on the waitlist was similar for men (9.3 ± 11.7 months) and women (9.9 ± 12.3 months; p=0.57). Both sexes were comparable in age (males: 53 ± 10 years; females: 52 ± 11 years; p=0.19), MELD (males: 18 ± 9; females: 19 ± 10; p=0.16) and BMI (males: 27.7 ± 5.7 kg/m²; females: 27.3 ± 6.6 kg/m²; p=0.58). Women had lower creatinine pre-LT (males: 1.1 ± 0.60 mg/dL; females 0.96 ± 0.51 mg/dL; p<0.01). There were no differences in donor age, sex or BMI. Women had significantly longer hospital length of stay (males: 18 days [IQR: 11, 32]; females: 25 days [IQR: 14, 43]; p <0.001). There was no difference in risk of acute kidney injury (OR 1.4 [95% CI: 0.98, 2.1]; p=0.06), infection (OR 1.1 [95% CI: 0.8, 1.5]; p=0.52) or rejection episodes (OR 1.1 [95% CI: 0.8, 1.5]; p=0.74) following LT. Women had a higher risk of CKD post-LT (OR 2.3 [95% CI: 1.6, 3.2]; p<0.0001). There was no difference in de-novo diabetes (males: 22%; females: 16%; p=0.10), hypertension (males: 45%; females: 48%; p=0.41), dyslipidemia (males: 37%; females: 39%; p=0.67) and CVD (males: 20%; females: 19%; p=0.84) post-LT. Graft (males: 11.4 ± 0.4 years; females: 11.8 ± 0.5 years; p=0.32) and patient survival (males: 11.8 ± 0.4 years; females: 12.4 ± 0.5 years; p=0.18) were similar over a median follow up of 6.3 years [IQR: 3.5, 9.9].

Conclusions

Women spend a longer time in hospital and are at an increased risk of CKD following LT. Despite these differences, overall graft and patient survival are comparable. Our data suggest the disparity between sexes likely exists pre-LT and females that undergo LT have similar outcomes to their male counterparts.

Funding Agencies

None

A224 COVID-19 INFECTION IN LIVER TRANSPLANT RECIPIENTS: CLINICAL FEATURES, HOSPITALIZATION, AND MORTALITY FROM A CANADIAN MULTICENTRE COHORT

Background

The COVID-19 pandemic has brought significant challenges to clinicians caring for liver transplant (LT) recipients. Researchers have sought to better understand the risk and clinical outcomes of LT recipients infected with COVID-19 globally, however, there is a paucity of data from within Canada.

Aims

Our multi-center study aims to examine the characteristics and clinical outcomes of LT patients with COVID-19 in Canada.

Methods

We identified a retrospective cohort of adult LT recipients with RT-PCR confirmed COVID-19 from 7 Canadian tertiary care centers between March 2020 and June 2021. Demographic and clinical data were compiled by clinicians within those centers. We identified liver enzyme profile at the time of COVID-19 infection, immunosuppression type and post-infection adjustments, rate of hospitalization, ICU admission, mechanical ventilation, and death.

Results

A total of 49 patients with a history of LT and COVID-19 infection were identified. Twenty nine patients (59%) were male, the median time from LT was 66 months (1, 128) and the median age at COVID-19 infection was 59 years (52, 65). At COVID-19 diagnosis, the median ALT was 37 U/L (21, 41), AST U/L was 34 (20, 37), ALP U/L was 156 (88, 156), Total Bilirubin was 11 umol/L (7, 14), and INR was 1.1 (1.0, 1.1). The majority of patients (92%) were on tacrolimus monotherapy or a combination of tacrolimus and mycophenolate mofetil (MMF); median tacrolimus level at COVID-19 diagnosis was 5.3 ug/L (4.0, 8.1). Immunosuppression was modified in 8 (16%) patients post-infection; either the tacrolimus dose was reduced or MMF was held. One patient developed acute cellular rejection which recovered after re-initiation of the prior regimen. Eighteen patients (37%) required hospitalization, 6 (12%) were treated with dexamethasone, and 3 (6%) required ICU admission and mechanical ventilation. Four patients (8%) died due to complications of COVID-19. On univariate analysis, neither age, sex, co-morbidities nor duration post-transplant were associated with risk of hospitalization.

Conclusions

In our national retrospective study, approximately 40% of patients required hospitalization with a mortality rate of &lt; 10%. Previous studies have shown proximity to LT as an independent factor for mortality with COVID-19; the median time from LT for our patients was 5 years, which may explain the lower mortality rate. Of note, the median tacrolimus levels were much lower in comparison to the target of 8–10 ug/L used in the first year post-transplant. As the landscape of COVID-19 changes with vaccination, evolving treatments, and increasing rates of variant transmission, additional studies are required to continue identifying trends in clinical outcomes.

Funding Agencies

None

The Bacteroidetes Aequorivita sp. and Kaistella jeonii Produce Promiscuous Esterases With PET-Hydrolyzing Activity

Certain members of the Actinobacteria and Proteobacteria are known to degrade polyethylene terephthalate (PET). Here, we describe the first functional PET-active enzymes from the Bacteroidetes phylum. Using a PETase-specific Hidden-Markov-Model- (HMM-) based search algorithm, we identified several PETase candidates from Flavobacteriaceae and Porphyromonadaceae. Among them, two promiscuous and cold-active esterases derived from Aequorivita sp. (PET27) and Kaistella jeonii (PET30) showed depolymerizing activity on polycaprolactone (PCL), amorphous PET foil and on the polyester polyurethane Impranil® DLN. PET27 is a 37.8 kDa enzyme that released an average of 174.4 nmol terephthalic acid (TPA) after 120 h at 30°C from a 7 mg PET foil platelet in a 200 μl reaction volume, 38-times more than PET30 (37.4 kDa) released under the same conditions. The crystal structure of PET30 without its C-terminal Por-domain (PET30ΔPorC) was solved at 2.1 Å and displays high structural similarity to the IsPETase. PET30 shows a Phe-Met-Tyr substrate binding motif, which seems to be a unique feature, as IsPETase, LCC and PET2 all contain Tyr-Met-Trp binding residues, while PET27 possesses a Phe-Met-Trp motif that is identical to Cut190. Microscopic analyses showed that K. jeonii cells are indeed able to bind on and colonize PET surfaces after a few days of incubation. Homologs of PET27 and PET30 were detected in metagenomes, predominantly aquatic habitats, encompassing a wide range of different global climate zones and suggesting a hitherto unknown influence of this bacterial phylum on man-made polymer degradation.

Minimally Invasive Surgical Approach for Esophageal Adenocarcinoma in a Patient with Previous Belsey Mark IV Fundoplication: A Case Report

Background: Historically, the management for recurrent or persistent Gastro-esophageal reflux disease included selective vagotomy and fundoplication. Despite these surgical interventions, the risk of Barrett’s esophagus (BE) and subsequent malignant transformation remains, requiring cancer resection surgery. We present a case of a patient with a gastro-esophageal junction (GEJ) adenocarcinoma, who underwent a pediatric thoracotomy and Belsey Mark IV fundoplication, and was successfully treated by Laparoscopic Ivor-Lewis Esophagectomy (LILE). Case Presentation: This 64-year-old gentleman with BE and GEJ adenocarcinoma was previously deemed unsuitable for curative surgery due to clinical staging indicating a tumor length of 10cm and suspected invasion of the left pleura. Further staging by Endoscopic ultrasound indicated no evidence of pleural invasion with the distal esophageal thickening in keeping with his previous Belsey Mark IV fundoplication. He underwent neo-adjuvant chemotherapy and a subsequent LILE with complete laparoscopic reversion of the gastric fundoplication without injury to the gastroepiploic artery or fundus. There was sufficient preservation of conduit length to enable a tension free hand-sewn anastomosis with an uneventful post-operative recovery. Final histopathology confirmed ypT1 ypN0 moderately differentiated adenocarcinoma with R0 resection margins. The patient has completed 24 months of cancer recurrence free surveillance. Conclusion: We describe the successful management of a patient by LILE on a background of previous hiatal fundoplication surgery, previously refused curative surgery. We highlight the importance of EUS as a staging modality for such cases showing invasive disease to increase the final clinical staging accuracy. We suggest a minimally invasive approach may be utilized for successful re-do hiatal dissection as an alternative to a conventional open surgery.

Bilateral idiopathic corneal opacity: A report of Ascher ring and a review of the literature

Purpose

To present a case of a rare entity of Ascher ring, a bilateral corneal stromal opacification.

Observation

A 70-year-old male with no ocular history who presented for cataract evaluation was found to have idiopathic bilateral circular stromal corneal rings.

Conclusions

After completion of extensive history, examination, imaging analyses, and laboratory studies for workup of corneal opacities, we arrived at a diagnosis of Ascher corneal ring, an extremely rare entity.

Importance

A rare entity should be considered after excluding other etiologies.

Abstract 600: Liquid biopsy for neuroendocrine differentiation: Validation of a circulating tumor cell assay for synaptophysin

Protein expression of synaptophysin (SYP) is characteristic of neuroendocrine subtype tumors. In prostate cancer, neuroendocrine differentiation is correlated with disease progression, poor prognosis, and treatment resistance. Analysis of circulating tumor cells (CTCs) by multiparameter immunofluorescence (IF) microscopy allows non-invasive characterization of cancer cell biomarker expression in real time. This information can be helpful in prognosis, treatment selection, and patient stratification. Here we describe the validation of a biomarker IF assay for enumeration of CTCs and characterization of their SYP expression. The 0920-VB SYP CTC assay workflow includes processing blood samples to slides (AccuCyte® Sample Preparation System), staining slides with a panel of fluorescent markers (RarePlex® Staining Kit and Ventana® DISCOVERY® ULTRA immunostaining system), and multiparameter imaging and analysis (CyteFinder® Instrument). The panel consists of a nuclear dye, and antibodies against cytokeratins and EpCAM (to identify epithelial CTCs), CD45 (to exclude white blood cells) and SYP. Both clinical and spike-in samples were used for assay validation. The model CTCs used to generate spike-in samples included 22Rv1 (prostate carcinoma, SYP positive) and BT-474 (breast carcinoma, SYP negative). Performance metrics for the assay included accuracy, sensitivity, specificity, repeatability, and intermediate precision of SYP detection and CTC enumeration. Single-cell SYP mean fluorescence intensities (MFI) were analyzed to determine protein expression levels. An MFI threshold for SYP positivity was established by maximizing the classification accuracy of the positive and negative cell lines. Using this threshold, 98.7% of 22Rv1 cells were correctly classified as SYP-positive, and 99.7% of BT474 cells were correctly classified as SYP-negative with an inter-run coefficient of variation of 13.9% for the 22Rv1 cell line. In clinical prostate, breast and colon cancer patient samples, subsets of CTCs were found to be SYP positive with the expected cytoplasmic localization of the marker. In summary, this liquid biopsy assay provides an analytically sensitive and specific method for CTC enumeration and SYP biomarker expression analysis, allowing non-invasive detection of neuroendocrine differentiation.

Citation Format: Jennifer Chow, A Anders Tevis, Edward Lo, Alisa Clein, Daniel E. Sabath, Arturo B. Ramirez, Eric P. Kaldjian, Tad George. Liquid biopsy for neuroendocrine differentiation: Validation of a circulating tumor cell assay for synaptophysin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 600.

The Komagataeibacter europaeus GqqA is the prototype of a novel bifunctional N-Acyl-homoserine lactone acylase with prephenate dehydratase activity

Previously, we reported the isolation of a quorum quenching protein (QQ), designated GqqA, from Komagataeibacter europaeus CECT 8546 that is highly homologous to prephenate dehydratases (PDT) (Valera et al. in Microb Cell Fact 15, 88. https://doi.org/10.1186/s12934-016-0482-y , 2016). GqqA strongly interfered with N-acyl-homoserine lactone (AHL) quorum sensing signals from Gram-negative bacteria and affected biofilm formation in its native host strain Komagataeibacter europaeus. Here we present and discuss data identifying GqqA as a novel acylase. ESI-MS-MS data showed unambiguously that GqqA hydrolyzes the amide bond of the acyl side-chain of AHL molecules, but not the lactone ring. Consistent with this observation the protein sequence does not carry a conserved Zn²⁺ binding motif, known to be essential for metal-dependent lactonases, but in fact harboring the typical periplasmatic binding protein domain (PBP domain), acting as catalytic domain. We report structural details for the native structure at 2.5 Å resolution and for a truncated GqqA structure at 1.7 Å. The structures obtained highlight that GqqA acts as a dimer and complementary docking studies indicate that the lactone ring of the substrate binds within a cleft of the PBP domain and interacts with polar residues Y16, S17 and T174. The biochemical and phylogenetic analyses imply that GqqA represents the first member of a novel type of QQ family enzymes.

Explanation-visualised deep learning model for accessory pathway localisation using 12-lead electrocardiography

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation Imperial Centre of Research Excellence

Background/Introduction

ECG algorithms for identifying accessory pathway (AP) locations are inaccurate and difficult to use. Human expert interpretation is poorly reproducible. Artificial intelligence (AI) techniques such as machine learning can improve accuracy in classification tasks by eschewing theory-driven predictions. More reproducible and accurate AP localisation could shorten procedure time and personalise ablation consent.

Purpose

We developed a neural network to perform AP localisation using 12-lead ECGs. Its decision-making process was analysed to enable explainability of the neural network.

Methods

A convolutional neural network was trained on raw, digital, intra-procedural 12-lead ECGs of patients with manifest APs who underwent successful ablation. ECGs were labelled with AP locations as left-sided, septal or right-sided using procedure reports, fluoroscopy and electro-anatomical maps. Accuracy of the neural network was assessed via 4-fold cross-validation and was compared to the Arruda algorithm. Five cardiologists were also assessed for their accuracy in determining locations in sub-groups of cases. The neural network was retrospectively analysed to identify areas of ECGs most influential to its predictions using importance mapping.

Results 

In 156 cases, accuracy of the neural network (92.9%) was significantly higher than the Arruda algorithm (76.9%; p &lt; 0.0001) and all five cardiologists (37.5% to 65.9%; p = 0.0001 to 0.0290). Importance mapping demonstrated that the QRS complexes of leads aVL and V1 were perceived as most influential, indicating interrogation of the lateral and anterior-posterior axes respectively.

The figure shows (A) architecture of the neural network, (B) accuracy of the neural network, Arruda algorithm and five cardiologists, (*, p = 0.05 – 0.01; **, p = 0.01 – 0.001; ***, p = 0.001 - 0.0001; ****, p &lt; 0.0001; as compared to the neural network) and (C) example importance maps for 12-lead ECGs of left-sided, septal and right-sided APs (in order from left to right), with darker regions corresponding to greater relative importance. 

Conclusion 

AI ECG interpretation allows accurate, reproducible prediction of AP locations, superior to conventional algorithms and human interpretation. Although AI decision-making is thought of as a ‘black box’, explanation visualisation techniques such as importance mapping allow humans to understand aspects of how a neural network make decisions. A prospectively validated neural network could be integrated into clinical practice to improve pre-procedural AP localisation. Abstract Figure. Summary of results

Non-selective and selective His bundle pacing both preserve left ventricular activation time and pattern

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation

Background: His bundle pacing can be achieved in two ways

selective His bundle pacing, where the His bundle is captured alone, and non-selective His bundle pacing, where local myocardium is also captured resulting a pre-excited ECG appearance. We assessed the impact of this ventricular pre-excitation on left and right ventricular dys-synchrony.

Methods

We recruited patients who displayed both selective and non-selective His bundle pacing. We performed non-invasive epicardial electrical mapping to determine left and right ventricular activation times and patterns.

Results

In the primary analysis (n = 20, all patients), non-selective His bundle pacing did not prolong LVAT compared to select His bundle pacing by a pre-specified non-inferiority margin of 10ms (LVAT prolongation: -5.5ms, 95% confidence interval (CI): -0.6 to -10.4, non-inferiority p &lt; 0.0001). Non-selective His bundle pacing did not prolong right ventricular activation time (4.3ms, 95%CI: -4.0 to 12.8, p = 0.296) but did prolong QRS duration (22.1ms, 95%CI: 11.8 to 32.4, p = 0.0003).

In patients with narrow intrinsic QRS (n = 6), non-selective His bundle pacing preserved left ventricular activation time (-2.9ms, 95%CI: -9.7 to 4.0, p = 0.331) but prolonged QRS duration (31.4ms, 95%CI: 22.0 to 40.7, p = 0.0003) and mean right ventricular activation time (16.8ms, 95%CI: -5.3 to 38.9, p = 0.108) compared to selective His bundle pacing.

Activation pattern of the left ventricular surface was unchanged between selective and non-selective His bundle pacing. Non-selective His bundle pacing produced early basal right ventricular activation, which was not observed with selective His bundle pacing.

Conclusions

Compared to selective His bundle pacing, local myocardial capture during non-selective His bundle pacing produces right ventricular pre-excitation resulting in prolongation of QRS duration. However, non-selective His bundle pacing preserves the left ventricular activation time and pattern of selective His bundle pacing. When choosing between selective and non-selective His bundle pacing, left ventricular dyssynchrony is not an important factor. Abstract Figure: Selective vs Non-Selective HBP

A promiscuous ancestral enzyme´s structure unveils protein variable regions of the highly diverse metallo-β-lactamase family

The metallo-β-lactamase fold is an ancient protein structure present in numerous enzyme families responsible for diverse biological processes. The crystal structure of the hyperthermostable crenarchaeal enzyme Igni18 from Ignicoccus hospitalis was solved at 2.3 Å and could resemble a possible first archetype of a multifunctional metallo-β-lactamase. Ancestral enzymes at the evolutionary origin are believed to be promiscuous all-rounders. Consistently, Igni18´s activity can be cofactor-dependently directed from β-lactamase to lactonase, lipase, phosphodiesterase, phosphotriesterase or phospholipase. Its core-domain is highly conserved within metallo-β-lactamases from Bacteria, Archaea and Eukarya and gives insights into evolution and function of enzymes from this superfamily. Structural alignments with diverse metallo-β-lactamase-fold-containing enzymes allowed the identification of Protein Variable Regions accounting for modulation of activity, specificity and oligomerization patterns. Docking of different substrates within the active sites revealed the basis for the crucial cofactor dependency of this enzyme superfamily.

Exploring the global metagenome for plastic-degrading enzymes

Plastics are extensively used in our daily life, but they are also a major pollutant of our biosphere accumulating in both the ocean and the land. In the recent years, few enzymes and microorganisms have been discovered with the ability to degrade even fewer synthetic polymers. Nevertheless, more active species and enzymes need to be discovered and described in order to gain more knowledge about protein adaptation to the degradation of not-naturally-occurring polymers. Within this chapter, we focus on efficient methods to identify novel polyethylene terephthalate-degrading enzymes (PETases) from culturable and non-culturable microorganisms by a combination of sequence- and function-based screening. This protocol can be adapted to discover other plastic hydrolases and in general for other enzymes, for which not many characterized specimens are yet available.

Sleep Well Be Well: Pilot of a digital intervention to improve child behavioural sleep problems

AIM

To investigate whether a digital sleep intervention improves child and care giver sleep and psychosocial outcomes.

METHODS

A total of 120 families with children aged 2-13 years, reporting moderate to severe child behavioural sleep problems, were recruited from a hospital sleep clinic waitlist or the community. Children from non-English speaking families, with known intellectual disability (IQ < 70) or severe medical problems excluded. Tailored behavioural sleep strategies were delivered to primary care givers via a smart phone app and complementary website. Eligible families completed a baseline questionnaire and child 'sleep check' then received the digital sleep intervention for 5 weeks, and then completed a post questionnaire.

OUTCOMES

care giver report of child sleep as no/mild versus moderate/severe problem over past month (primary outcome); problem child sleep patterns (Brief Infant Sleep Questionnaire or Child Sleep Habits Questionnaire), child temperament, care giver mental health (Kessler 6), care giver sleep, health service use for their child's sleep and time off work/activities to access services.

RESULTS

At follow up, care givers reported fewer moderate/severe child sleep problems (84.6-40.7%), improved problem child sleep patterns, better temperament and improved care giver mental health. Care giver sleep quality and quantity remained unchanged. Health service use (averaged over a 6-month period pre- and post-intervention) fell from 18.9% pre- to 14.1% post-intervention.

CONCLUSION

A digital sleep intervention appears promising in improving sleep in children with moderate/severe behavioural sleep problems, and care giver mental health. It may be a useful alternative to face-to-face management of behavioural sleep problems.

Pulmonary artery catheterization in cardiogenic shock: a systematic review and meta-analysis

Background

Cardiogenic shock carries high morbidity and mortality. Pulmonary artery catheterization (PAC) allows invasive hemodynamic assessment and tailored therapy; however, evidence supporting this practice is sparse.

Methods

We performed a systematic review and meta-analysis of observational studies and randomized controlled trials comparing PAC versus no PAC in cardiogenic shock. We searched MEDLINE, EMBASE, Cochrane CENTRAL, and grey literature. We screened references, abstracted data and evaluated risk of bias in duplicate. We pooled data using a random-effects model and evaluated the quality of evidence using GRADE. Outcomes of interest were mortality and length of stay (LOS).

Results

We identified 13 observational studies (1,982,047 patients) and no randomized controlled trials; 12 studies were at high risk of bias. When pooling adjusted results, PAC was associated with reduced mortality at hospital discharge (RR 0.64; 95% CI 0.50–0.82) and at longest available follow-up (RR 0.65; 95% CI 0.49–0.87). Unadjusted LOS was 5.0 days longer (95% CI 4.93–5.07) with PAC. Quality of evidence was very low for all outcomes.

Conclusion

Based on very low quality evidence, PAC use in patients with cardiogenic shock may be associated with lower mortality. The observed increase in hospital LOS may represent survivor bias or relate to more aggressive management with PAC. Overall, these results support consideration of PAC for hemodynamic assessment and tailored therapy in cardiogenic shock.

Funding Acknowledgement

Type of funding source: None

Abstract P4-06-09: Pick-Seq®: Multi-parameter imaging combined with RNA sequencing of tissue section micro-regions for spatial analysis in breast carcinoma

Multi-parameter tissue imaging allows for a contextual understanding of tumor cells in relation to the tumor microenvironment. Pick-Seq is a novel workflow uniquely enabled by the RareCyte CyteFinder® Instrument that combines interrogation of multiple protein markers with investigation of gene expression from selected micro-regions on tissue slides. In this study, formalin-fixed, paraffin-embedded tonsil sections and OCT-embedded, frozen breast cancer sections were stained with epithelial and lymphocyte markers by multi-parameter immunofluorescence (IF) and scanned with the CyteFinder Instrument to identify regions of interest. Based on IF staining patterns, 40 μm diameter micro-regions were retrieved with the integrated CytePicker® Retrieval Module. Micro-region RNA was isolated for whole transcriptome amplification, library preparation, and sequencing. Resulting data were analyzed for differential gene expression, cell composition, and T cell receptor (TCR) sequences. Transcriptomic analysis of tonsil micro-regions confirmed increased expression of B cell markers in follicles and T cell markers in the T cell zone. CIBERSORT revealed distinct cellular compositions between T cell zones and the B cell follicles. Principle component analysis of gene expression found that micro-regions retrieved from the two follicles clustered independently from each other, and from the T cell zone micro-regions. Fragments per kilobase million (FPKM) analysis revealed differing expression of genes, particularly CD19 and CD21, between the adjacent follicles. Subsequent staining confirmed differential protein expression, indicating that only one follicle contained a germinal center. In breast carcinoma, regions were identified for CytePicker retrieval that included (1) tumor cells, (2) tumor cells with interspersed tumor infiltrating lymphocytes (TIL), or (3) adjacent lymphoid aggregates. CIBERSORT analysis demonstrated the presence of T cell-associated transcriptomic profiles in lymphoid aggregates and in TIL-containing micro-regions that were proportional to the number of T cells retrieved. Aligned RNA-seq reads were further analyzed to identify TCR α and β chain sequences from retrieved TILs. These data establish the potential of combining multi-parameter IF microscopy with deep RNA sequencing as a powerful tool for investigation and biomarker discovery in the immuno-oncology of breast cancer.

Citation Format: Nolan Ericson, Rebecca Podyminogin, Jennifer Chow, Jia-Ren Lin, Yu-An Chen, Zoltan Maliga, Peter Sorger, Kyla Teplitz, Eric Kaldjian, Tad George. Pick-Seq®: Multi-parameter imaging combined with RNA sequencing of tissue section micro-regions for spatial analysis in breast carcinoma [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-06-09.

Plastics: Environmental and Biotechnological Perspectives on Microbial Degradation

Plastics are widely used in the global economy, and each year, at least 350 to 400 million tons are being produced. Due to poor recycling and low circular use, millions of tons accumulate annually in terrestrial or marine environments. Today it has become clear that plastic causes adverse effects in all ecosystems and that microplastics are of particular concern to our health. Therefore, recent microbial research has addressed the question of if and to what extent microorganisms can degrade plastics in the environment. This review summarizes current knowledge on microbial plastic degradation. Enzymes available act mainly on the high-molecular-weight polymers of polyethylene terephthalate (PET) and ester-based polyurethane (PUR). Unfortunately, the best PUR- and PET-active enzymes and microorganisms known still have moderate turnover rates. While many reports describing microbial communities degrading chemical additives have been published, no enzymes acting on the high-molecular-weight polymers polystyrene, polyamide, polyvinylchloride, polypropylene, ether-based polyurethane, and polyethylene are known. Together, these polymers comprise more than 80% of annual plastic production. Thus, further research is needed to significantly increase the diversity of enzymes and microorganisms acting on these polymers. This can be achieved by tapping into the global metagenomes of noncultivated microorganisms and dark matter proteins. Only then can novel biocatalysts and organisms be delivered that allow rapid degradation, recycling, or value-added use of the vast majority of most human-made polymers.

Decoding the ocean's microbiological secrets for marine enzyme biodiscovery

A global census of marine microbial life has been underway over the past several decades. During this period, there have been scientific breakthroughs in estimating microbial diversity and understanding microbial functioning and ecology. It is estimated that the ocean, covering 71% of the earth's surface with its estimated volume of about 2 × 10¹⁸ m³ and an average depth of 3800 m, hosts the largest population of microbes on Earth. More than 2 million eukaryotic and prokaryotic species are thought to thrive both in the ocean and on its surface. Prokaryotic cell abundances can reach densities of up to 10¹² cells per millilitre, exceeding eukaryotic densities of around 10⁶ cells per millilitre of seawater. Besides their large numbers and abundance, marine microbial assemblages and their organic catalysts (enzymes) have a largely underestimated value for their use in the development of industrial products and processes. In this perspective article, we identified critical gaps in knowledge and technology to fast-track this development. We provided a general overview of the presumptive microbial assemblages in oceans, and an estimation of what is known and the enzymes that have been currently retrieved. We also discussed recent advances made in this area by the collaborative European Horizon 2020 project ‘INMARE’.

Igni18, a novel metallo-hydrolase from the hyperthermophilic archaeon Ignicoccus hospitalis KIN4/I: cloning, expression, purification and X-ray analysis

The hyperthermophilic crenarchaeon Ignicoccus hospitalis KIN4/I possesses at least 35 putative genes encoding enzymes that belong to the α/β-hydrolase superfamily. One of those genes, the metallo-hydrolase-encoding igni18, was cloned and heterologously expressed in Pichia pastoris. The enzyme produced was purified in its catalytically active form. The recombinant enzyme was successfully crystallized and the crystal diffracted to a resolution of 2.3 Å. The crystal belonged to space group R32, with unit-cell parameters a = b = 67.42, c = 253.77 Å, α = β = 90.0, γ = 120.0°. It is suggested that it contains one monomer of Igni18 within the asymmetric unit.

1537. Reactivation of Latent Cytomegalovirus Infection in Patients with Rheumatologic Disease: A Case–Control Study

Background

While there are emerging reports of cytomegalovirus (CMV) disease in patients with underlying rheumatic conditions, the disease burden, risk factors and clinical sequelae in this population are poorly understood. We sought to describe a cohort of patients with underlying rheumatic disease and CMV infection, then compare those with systemic lupus erythematosus (SLE), the largest subgroup, using case–control methodology to identify risk factors for reactivation and differences in outcomes.

Methods

Adults with rheumatic disease and CMV reactivation diagnosed by viral load, viral culture or histopathology from Tufts Medical Center between 2000 and 2015 were identified. Due to SLE cases comprising 43% of the total, these patients were matched 3:1 with SLE controls based on age, sex and year of admission.

Results

Fourteen patients with rheumatic disease and CMV were included (six SLE, four rheumatoid arthritis, two sarcoid, one psoriatic arthritis, one microscopic polyangiitis). Seven patients had viremia alone and the remainder had tissue-invasive disease (four gastrointestinal, three pulmonary). Thirteen (93%) received corticosteroids within 3 months prior to CMV reactivation. Fever (86%) was the most common symptom. Coinfections were seen in eight (57%), including four with bacteremia. Thirteen (93%) were treated with antiviral therapy for a median of 33 days (range 13–171). Relapse occurred in three patients and four died during hospitalization. Six patients with underlying SLE and CMV reactivation were compared with 18 controls. Cases received significantly more corticosteroids during the 8-week period prior to admission (median 36.5 vs. 2.5 mg/day, P = 0.006), had longer hospitalizations (median 46.5 vs. 6.5 days, P = 0.006) and more frequent co-infections (67% vs. 17%, P = 0.04). There were no significant differences in symptoms at presentation.

Conclusion

CMV reactivation occurs in patients with rheumatic disease, and can result in severe clinical sequelae that may be difficult to distinguish from a flare of the underlying disease. Patients with CMV were more likely to have received high doses of corticosteroids, and developed more co-infections during their hospitalization. Clinicians should consider this diagnosis during the evaluation of a febrile illness in the rheumatologic population.

Disclosures

D. Snydman, Merck: Board Member, Consulting fee and Grant recipient; Shire: Board Member, Consulting fee; Takeda: Board Member, Consulting fee; Chimerix: Board Member, Consulting fee; Seres Therapeutics: Grant Investigator, Grant recipient; Actelion: Grant Investigator, Grant recipient; Moderna: Board Member, Consulting fee; Summit: Grant Investigator, Grant recipient; Tetraphase: Grant Investigator, Grant recipient.

2506. Reactivation of Latent Cytomegalovirus Infection Following Major Surgery: Risk Factors and Outcomes

Background

Reactivation of latent cytomegalovirus infection can occur in nonimmunocompromised individuals during critical illness and may be associated with increased morbidity and mortality. However, few studies have focused on patients undergoing major surgery. Our aim was to explore risk factors for and outcomes following CMV reactivation in nonimmunocompromised post-operative patients.

Methods

We performed a retrospective case–control study of nonimmunocompromised patients with CMV reactivation following major surgery from 2004 to 2016. Cases included patients testing positive for CMV by viral load, viral culture or histopathology. Controls were matched to cases 2:1 by age, sex, type and year of surgery. Groups were compared using conditional logistic regression.

Results

16 patients with CMV were matched to 32 controls. Median age was 65 (range 34–84) and 50% were male. The most common surgeries were abdominal (44%) and cardiac (25%). Median time from surgery to CMV diagnosis was 32 days (range 17–93). Patients had a range of clinical symptoms including fever (94%), hepatitis (75%), bone marrow suppression (56%) and gastrointestinal symptoms (56%). All except one were treated with antiviral therapy. Despite having similar baseline Charlson comorbidity scores, cases were more likely to return to surgery within 3 months (odds ratio, OR 6.31; 95% CI, 1.29–30.74), require renal replacement therapy (OR 18.54, 2.36–145.6), total parenteral nutrition (OR 33.0, 6.60–262.37) and corticosteroids (OR 18.78, 4.5–103.9). Length of stay was increased (median 51 vs. 8 days, P = 0.005), coinfections were more common (OR 15.10, 1.89–120.8), and in-hospital mortality was significantly higher (38% vs. 0%, P < 0.01).

Conclusion

Reactivation of CMV occurs in nonimmunocompromised patients post-operatively and is associated with poor outcomes including other infections and mortality. Potential risk factors include prolonged length of stay, development of surgical complications, and prolonged use of corticosteroids. It is not clear from our study if CMV reactivation is a surrogate marker of severe illness and postoperative complications, or if CMV reactivation plays a causative role in the development of these adverse outcomes.

Disclosures

D. Snydman, Merck: Board Member, Consulting fee and Grant recipient. Shire: Board Member, Consulting fee. Takeda: Board Member, Consulting fee. Chimerix: Board Member, Consulting fee. Seres Therapeutics: Grant Investigator, Grant recipient. Actelion: Grant Investigator, Grant recipient. Moderna: Board Member, Consulting fee. Summit: Grant Investigator, Grant recipient. Tetraphase: Grant Investigator, Grant recipient.

1551. The Impact of Recurrent CMV Disease on Long-Term Survival in Solid Organ Transplant Recipients

Background

Cytomegalovirus (CMV) remains a significant contributor to morbidity and mortality following solid-organ transplantation (SOT). While relapse after treatment completion can occur in up to 30% of patients, the effect of this on mortality is not clear. The aim of this study was to explore the impact of recurrent CMV disease on long-term survival in SOT recipients.

Methods

We performed a retrospective cohort study of heart, liver and kidney transplant recipients who completed treatment for an episode of CMV disease. Data on potential confounders were collected from the time of CMV treatment completion. Censoring occurred at the time of death, loss to follow-up or 10 years. Univariable and multivariable hazard ratios (HR) were calculated using a Cox model, treating relapse and rejection following CMV as time-varying covariates.

Results

Seventy-nine kidney, 52 heart, 34 liver and five liver-kidney transplant recipients were included. Sixty-two of 170 died, at a median of 3.8 years (interquartile range [IQR] 0.8–6.6 years). Median follow-up amongst the 108 survivors was 7.4 years (IQR 3.7–10 years) although 22 (13%) were censored before 3 years. CMV relapse occurred in 49/170 (29%), 67% within 6 months of treatment completion. Overall mortality amongst those who relapsed was 39% (19/49) vs. 36% (43/121) in those who remained relapse free. On univariable analysis, CMV relapse was not associated with a significantly increased risk of death (unadjusted HR 1.59, 95% CI 0.92–2.75, P = 0.10). After controlling for age and transplanted organ type, findings were similar (adjusted HR 1.68, 95% CI 0.93–3.04, P = 0.09).

Conclusion

Mortality rates following CMV remain high even in the valganciclovir era. In our study, we did not identify a significant relationship between the development of recurrent CMV disease and death. However, the complex nature of these patients, multiple layers of potential confounding and limited statistical power of our cohort make detection of small effects difficult. Future prospective studies evaluating the clinical efficacy of strategies to reduce recurrence are needed to further assess this relationship.

Disclosures

D. Snydman, Merck: Board Member, Consulting fee and Grant recipient; Shire: Board Member, Consulting fee; Takeda: Board Member, Consulting fee; Chimerix: Board Member, Consulting fee; Seres Therapeutics: Grant Investigator, Grant recipient; Actelion: Grant Investigator, Grant recipient; Moderna: Board Member, Consulting fee; Summit: Grant Investigator, Grant recipient; Tetraphase: Grant Investigator, Grant recipient.

Reliable detection of subchromosomal deletions and duplications using cell-based noninvasive prenatal testing

Objective

To gather additional data on the ability to detect subchromosomal abnormalities of various sizes in single fetal cells isolated from maternal blood, using low‐coverage shotgun next‐generation sequencing for cell‐based noninvasive prenatal testing (NIPT).

Method

Fetal trophoblasts were recovered from approximately 30 mL of maternal blood using maternal white blood cell depletion, density‐based cell separation, immunofluorescence staining, and high‐resolution scanning. These trophoblastic cells were picked as single cells and underwent whole genome amplification for subsequent genome‐wide copy number analysis and genotyping to confirm the fetal origin of the cells.

Results

Applying our fetal cell isolation method to a series of 125 maternal blood samples, we detected on average 4.17 putative fetal cells/sample. The series included 15 cases with clinically diagnosed fetal aneuploidies and five cases with subchromosomal abnormalities. This method was capable of detecting findings that were 1 to 2 Mb in size, and all were concordant with the microarray or karyotype data obtained on a fetal sample. A minority of fetal cells showed evidence of genome degradation likely related to apoptosis.

Conclusion

We demonstrate that this cell‐based NIPT method has the capacity to reliably diagnose fetal chromosomal abnormalities down to 1 to 2 Mb in size.

What is already known about this topic?

Fetal trophoblastic cells can be isolated from maternal blood and be used for the detection of fetal aneuploidies and copy number variants. The data on the detection of subchromosomal deletions and duplications is currently limited.

What does this study add?

Cell‐based NIPT can be used for the detection of copy number abnormalities of greater than or equal to 1 Mb in the fetus by low‐coverage next‐generation sequencing after single cell whole genome amplification. Data are provided here for five cases in which different subchromosomal deletions and duplications ranging from 1.2 to 18.9 Mb were detected in single cells.

The Thaumarchaeon N. gargensis carries functional bioABD genes and has a promiscuous E. coli ΔbioH-complementing esterase EstN1

Biotin is an essential cofactor required for carboxylation and decarboxylation reactions in all domains of life. While biotin biosynthesis in most Bacteria and Eukarya is well studied, the complete pathway for this vitamer in Archaea is still not known. Detailed genome searches indicated the presence of possible bio gene clusters only in Methanococcales and Thaumarchaeota. Therefore, we analysed the functionality of the predicted genes bioA, bioB, bioD and bioF in the Thaumarchaeon Nitrososphaera gargensis Ga2.9 which are essential for the later steps of biotin synthesis. In complementation tests, the gene cluster-encoded N. gargensis bioABD genes except bioF restored growth of corresponding E. coli Rosetta-gami 2 (DE3) deletion mutants. To find out how biotin biosynthesis is initiated, we searched the genome for a possible bioH analogue encoding a pimeloyl-ACP-methylester carboxylesterase. The respective amino acid sequence of the ORF estN1 showed weak conserved domain similarity to this class of enzymes (e-value 3.70e-42). Remarkably, EstN1 is a promiscuous carboxylesterase that complements E. coli ΔbioH and Mesorhizobium loti ΔbioZ mutants for growth on biotin-free minimal medium. Additional 3D-structural models support the hypothesis that EstN1 is a BioH analogue. Thus, this is the first report providing experimental evidence that Archaea carry functional bio genes.

RareCyte® CTC Analysis Step 3: Using the CytePicker® Module for Individual Cell Retrieval and Subsequent Whole Genome Amplification of Circulating Tumor Cells for Genomic Analysis

The CytePicker module built into the RareCyte CyteFinder instrument allows researchers to easily retrieve individual cells from microscope slides for genomic analyses, including array CGH, targeted sequencing, and next-generation sequencing. Here, we describe the semiautomated retrieval of CTCs from the blood processed by AccuCyte (see Chapter 13) and amplification of genomic DNA so that molecular analysis can be performed.

New Insights into the Function and Global Distribution of Polyethylene Terephthalate (PET)-Degrading Bacteria and Enzymes in Marine and Terrestrial Metagenomes

Polyethylene terephthalate (PET) is one of the most important synthetic polymers used today. Unfortunately, the polymers accumulate in nature and to date no highly active enzymes are known that can degrade it at high velocity. Enzymes involved in PET degradation are mainly α- and β-hydrolases, like cutinases and related enzymes (EC 3.1.1). Currently, only a small number of such enzymes are well characterized. In this work, a search algorithm was developed that identified 504 possible PET hydrolase candidate genes from various databases. A further global search that comprised more than 16 Gb of sequence information within 108 marine and 25 terrestrial metagenomes obtained from the Integrated Microbial Genome (IMG) database detected 349 putative PET hydrolases. Heterologous expression of four such candidate enzymes verified the function of these enzymes and confirmed the usefulness of the developed search algorithm. In this way, two novel and thermostable enzymes with high potential for downstream application were partially characterized. Clustering of 504 novel enzyme candidates based on amino acid similarities indicated that PET hydrolases mainly occur in the phyla of Actinobacteria, Proteobacteria, and Bacteroidetes Within the Proteobacteria, the Betaproteobacteria, Deltaproteobacteria, and Gammaproteobacteria were the main hosts. Remarkably enough, in the marine environment, bacteria affiliated with the phylum Bacteroidetes appear to be the main hosts of PET hydrolase genes, rather than Actinobacteria or Proteobacteria, as observed for the terrestrial metagenomes. Our data further imply that PET hydrolases are truly rare enzymes. The highest occurrence of 1.5 hits/Mb was observed in sequences from a sample site containing crude oil.IMPORTANCE Polyethylene terephthalate (PET) accumulates in our environment without significant microbial conversion. Although a few PET hydrolases are already known, it is still unknown how frequently they appear and with which main bacterial phyla they are affiliated. In this study, deep sequence mining of protein databases and metagenomes demonstrated that PET hydrolases indeed occur at very low frequencies in the environment. Furthermore, it was possible to link them to phyla that were previously not known to harbor such enzymes. This work contributes novel knowledge on the phylogenetic relationships, the recent evolution, and the global distribution of PET hydrolases. Finally, we describe the biochemical traits of four novel PET hydrolases.

Determinants and Prediction of Esterase Substrate Promiscuity Patterns

Esterases receive special attention because of their wide distribution in biological systems and environments and their importance for physiology and chemical synthesis. The prediction of esterases' substrate promiscuity level from sequence data and the molecular reasons why certain such enzymes are more promiscuous than others remain to be elucidated. This limits the surveillance of the sequence space for esterases potentially leading to new versatile biocatalysts and new insights into their role in cellular function. Here, we performed an extensive analysis of the substrate spectra of 145 phylogenetically and environmentally diverse microbial esterases, when tested with 96 diverse esters. We determined the primary factors shaping their substrate range by analyzing substrate range patterns in combination with structural analysis and protein-ligand simulations. We found a structural parameter that helps rank (classify) the promiscuity level of esterases from sequence data at 94% accuracy. This parameter, the active site effective volume, exemplifies the topology of the catalytic environment by measuring the active site cavity volume corrected by the relative solvent accessible surface area (SASA) of the catalytic triad. Sequences encoding esterases with active site effective volumes (cavity volume/SASA) above a threshold show greater substrate spectra, which can be further extended in combination with phylogenetic data. This measure provides also a valuable tool for interrogating substrates capable of being converted. This measure, found to be transferred to phosphatases of the haloalkanoic acid dehalogenase superfamily and possibly other enzymatic systems, represents a powerful tool for low-cost bioprospecting for esterases with broad substrate ranges, in large scale sequence data sets.