Using machine learning probabilities to identify effects of COVID-19

Coronavirus disease 2019 (COVID-19), the disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, has had extensive economic, social, and public health impacts in the United States and around the world. To date, there have been more than 600 million reported infections worldwide with more than 6 million reported deaths. Retrospective analysis, which identified comorbidities, risk factors, and treatments, has underpinned the response. As the situation transitions to an endemic, retrospective analyses using electronic health records will be important to identify the long-term effects of COVID-19. However, these analyses can be complicated by incomplete records, which makes it difficult to differentiate visits where the patient had COVID-19. To address this issue, we trained a random Forest classifier to assign a probability of a patient having been diagnosed with COVID-19 during each visit. Using these probabilities, we found that higher COVID-19 probabilities were associated with a future diagnosis of myocardial infarction, urinary tract infection, acute renal failure, and type 2 diabetes.

Natural Language Processing Can Automate Extraction of Barrett's Esophagus Endoscopy Quality Metrics

Objectives

To develop an automated natural language processing (NLP) method for extracting high-fidelity Barrett's Esophagus (BE) endoscopic surveillance and treatment data from the electronic health record (EHR).

Methods

Patients who underwent BE-related endoscopies between 2016 and 2020 at a single medical center were randomly assigned to a development or validation set. Those not aged 40 to 80 and those without confirmed BE were excluded. For each patient, free text pathology reports and structured procedure data were obtained. Gastroenterologists assigned ground truth labels. An NLP method leveraging MetaMap Lite generated endoscopy-level diagnosis and treatment data. Performance metrics were assessed for this data. The NLP methodology was then adapted to label key endoscopic eradication therapy (EET)-related endoscopy events and thereby facilitate calculation of patient-level pre-EET diagnosis, endotherapy time, and time to CE-IM.

Results

99 patients (377 endoscopies) and 115 patients (399 endoscopies) were included in the development and validation sets respectively. When assigning high-fidelity labels to the validation set, NLP achieved high performance (recall: 0.976, precision: 0.970, accuracy: 0.985, and F1-score: 0.972). 77 patients initiated EET and underwent 554 endoscopies. Key EET-related clinical event labels had high accuracy (EET start: 0.974, CE-D: 1.00, and CE-IM: 1.00), facilitating extraction of pre-treatment diagnosis, endotherapy time, and time to CE-IM.

Conclusions

High-fidelity BE endoscopic surveillance and treatment data can be extracted from routine EHR data using our automated, transparent NLP method. This method produces high-level clinical datasets for clinical research and quality metric assessment.

Hysterectomy Trends and Risk of Vaginal Cuff Dehiscence: An Update by Mode of Surgery

STUDY OBJECTIVE

To analyze hysterectomy trends and vaginal cuff dehiscence (VCD) rates by mode of surgery at a tertiary care medical center and to describe characteristics of VCD cases.

DESIGN

Observational retrospective cohort study.

SETTING

Large academic hospital and affiliated community hospital.

PATIENTS

4722 patients who underwent hysterectomy at Columbia University Irving Medical Center between January 2010 and August 2021.

INTERVENTIONS

Current Procedural Terminology and International Classification of Diseases codes identified hysterectomies and VCD cases. Hysterectomy trends and VCD rates were calculated by mode of surgery. Relative risks of VCD for each mode were compared with total abdominal hysterectomy (TAH). Clinical characteristics of VCDs were reviewed.

MEASUREMENTS AND MAIN RESULTS

There were 4059 total hysterectomies. Laparoscopic hysterectomies, including total laparoscopic hysterectomies (TLHs), laparoscopic-assisted vaginal hysterectomies, and robot-assisted TLHs (RA-TLHs), increased from 41.9% in 2010 to 65.9% in 2021 (p <.001). RA-TLH increased from 5.7% in 2010 to 40.2% in 2021. Supracervical hysterectomies followed similar trends and were excluded from VCD analysis. There were 15 VCDs (overall rate 0.37%). VCD was highest after RA-TLH (0.66%), followed by TLH (0.32%) and TAH (0.27%), with no VCDs after laparoscopic-assisted vaginal hysterectomy or total vaginal hysterectomy. Compared with TAH, the relative risk for VCD after RA-TLH was 2.44 (95% confidence interval 0.66-9.00) and after TLH was 1.18 (95% confidence interval 0.24-5.83), which were not statistically significant. The mean time to dehiscence was 39 days (range 8-145 days). The most common trigger event was coitus (41%).

CONCLUSION

VCD rates were low (<1%) for all modes of hysterectomy, and rates after robotic and laparoscopic hysterectomy were much lower than previously reported. Although VCD rates trended higher after robotic and laparoscopic hysterectomy compared with abdominal hysterectomy, the difference was not significant. It is difficult to determine whether this finding represents true lack of difference vs a lack of power to detect a significant difference given the rarity of VCD.

Breast cancer risk prediction combining a convolutional neural network-based mammographic evaluation with clinical factors

PURPOSE

Deep learning techniques, including convolutional neural networks (CNN), have the potential to improve breast cancer risk prediction compared to traditional risk models. We assessed whether combining a CNN-based mammographic evaluation with clinical factors in the Breast Cancer Surveillance Consortium (BCSC) model improved risk prediction.

METHODS

We conducted a retrospective cohort study among 23,467 women, age 35-74, undergoing screening mammography (2014-2018). We extracted electronic health record (EHR) data on risk factors. We identified 121 women who subsequently developed invasive breast cancer at least 1 year after the baseline mammogram. Mammograms were analyzed with a pixel-wise mammographic evaluation using CNN architecture. We used logistic regression models with breast cancer incidence as the outcome and predictors including clinical factors only (BCSC model) or combined with CNN risk score (hybrid model). We compared model prediction performance via area under the receiver operating characteristics curves (AUCs).

RESULTS

Mean age was 55.9 years (SD, 9.5) with 9.3% non-Hispanic Black and 36% Hispanic. Our hybrid model did not significantly improve risk prediction compared to the BCSC model (AUC of 0.654 vs 0.624, respectively, p = 0.063). In subgroup analyses, the hybrid model outperformed the BCSC model among non-Hispanic Blacks (AUC 0.845 vs. 0.589; p = 0.026) and Hispanics (AUC 0.650 vs 0.595; p = 0.049).

CONCLUSION

We aimed to develop an efficient breast cancer risk assessment method using CNN risk score and clinical factors from the EHR. With future validation in a larger cohort, our CNN model combined with clinical factors may help predict breast cancer risk in a cohort of racially/ethnically diverse women undergoing screening.

Lack of Age-Appropriate Reference Intervals Causing Potentially Missed Alerts in Clinical Reports of Dyslipidemia

This study shows that only 12.5% of laboratory reports (2/16) included age-appropriate pediatric reference ranges for all lipid and lipoproteins. The use of erroneous reference range(s) could lead to missed alerts of dyslipidemia in up to 97.3% (total cholesterol), 93.6% (high-density lipoprotein cholesterol), 94.8% (low-density lipoprotein cholesterol), and 87.8% (triglycerides) of youth in the population-based National Health and Nutrition Examination Survey cohort. These findings highlight the potential missed opportunities for reinforcing lifestyle counseling for dyslipidemia in addition to obesity in youth.

Deep learning on time series laboratory test results from electronic health records for early detection of pancreatic cancer

e16268

Background: Pancreatic cancer (PC) has a uniquely poor survival rate due to the absence of proven and effective methods for early detection. We thus aimed to leverage recent advances in deep learning towards the task of inferring early risk of PC from longitudinal laboratory test data contained within Electronic Health Records (EHR) data. Methods: In this study, we develop a novel deep learning framework for incorporating longitudinal clinical data from EHR to infer risk for PC. This framework includes a novel training protocol, which enforces an emphasis on early detection by applying an independent Poisson-random mask on proximal-time measurements for each variable. Data fusion for irregular multivariate time-series features is enabled by a “grouped” neural network (GrpNN) architecture, which uses representation learning to generate a dimensionally reduced vector for each measurement set before generating a final prediction. These models were evaluated using EHR data from Tripartite Request Assessment Committee (TRAC). Results: Our framework demonstrated better performance on early detection (AUROC 0.671, CI 95% 0.667–0.675, p < 0.001) at 12 months prior to diagnosis compared to a logistic regression and a feedforward neural network baseline (black-box model). We demonstrate that our masking strategy results greater improvements at distal times prior to diagnosis, and that our GrpNN model improves generalizability by reducing overfitting relative to the feedforward baseline (Table). The results were consistent across reported race. Conclusions: Our study presents new approaches for integrating multimodal longitudinal clinical data with bias reduction strategies which results in improved early detection of PC. This study demonstrates for the first time the utility of multivariate time series laboratory test results for early detection of PC. Our proposed algorithm is potentially generalizable to improve risk predictions for other types of cancer and other diseases where early detection can improve survival. We split data into train set (80%) and hold-out set (20%) and presented mean AUROC and AUPRC with 95% confidence intervals.[Table: see text]

Immunotherapy related pericardial effusion on chest CT

BACKGROUND

Immunotherapy has become a critical class of anticancer therapy in recent years, functioning by releasing brakes on the immune system that ultimately results in immune cell activation which eliminates cancer cells. Immune related adverse events (IRAEs) are a specific type of adverse event described in patients taking checkpoint inhibitor immunotherapy which results from unrestrained immune activation. Immune related pericardial effusion has been described however has not been comprehensively characterized. Here, we present the most extensive report to date detailing this adverse event.

METHODS

We queried our medical record system to retrospectively identify patients on checkpoint inhibitor therapy for lung cancer who subsequently developed pericardial effusion. We analyzed the clinical and radiographic characteristics, prior therapies, treatment for the effusion, and outcomes in patients with immune related pericardial effusion and compared them to similar patients with pericardial effusion not attributable to checkpoint inhibitor therapy.

RESULTS

Our data demonstrate that most of these pericardial effusions were small and not clinically significant. The majority were successfully treated with steroids or resolved spontaneously. Anti-PD-1 inhibitors were the most common checkpoint inhibitor preceding pericardial effusion, and a significant number of patients who went on to develop IRAE pericardial effusion previously had treatment with carboplatin for their cancer.

CONCLUSIONS

These data suggest that IRAE pericardial effusion is not a clinically significant adverse event however it sometimes leads to permanent discontinuation of checkpoint inhibitor therapy which is not necessary.

Prevalence of Clostridioides difficile and Other Gastrointestinal Pathogens in Patients with COVID-19

BACKGROUND

Gastrointestinal symptoms are common in patients with COVID-19, but prevalence of co-infection with enteric pathogens is unknown.

AIMS

This study assessed the prevalence of enteric infections among hospitalized patients with COVID-19.

METHODS

We evaluated 4973 hospitalized patients ≥ 18 years of age tested for COVID-19 from March 11 through April 28, 2020, at two academic hospitals. The primary exposure was a positive COVID-19 test. The primary outcome was detection of a gastrointestinal pathogen by PCR stool testing.

RESULTS

Among 4973 hospitalized individuals, 311 were tested for gastrointestinal infections (204 COVID-19 positive, 107 COVID-19 negative). Patients with COVID-19 were less likely to test positive compared to patients without COVID-19 (10% vs 22%, p < 0.01). This trend was driven by lower rates of non-C.difficile infections (11% vs 22% in COVID-19 positive vs. negative, respectively, p = 0.04), but not C. difficile infection (5.1% vs. 8.2%, p = 0.33). On multivariable analysis, infection with COVID-19 remained significantly associated with lower odds of concurrent GI infection (aOR 0.49, 95% CI 0.24-0.97), again driven by reduced non-C.difficile infection. Testing for both C.difficile and non-C.difficile enteric infection decreased dramatically during the pandemic.

CONCLUSIONS

Pathogens aside from C.difficile do not appear to be a significant contributor to diarrhea in COVID-19 positive patients.

Electronic Medical Record Search Engine (EMERSE): An Information Retrieval Tool for Supporting Cancer Research

PURPOSE

The Electronic Medical Record Search Engine (EMERSE) is a software tool built to aid research spanning cohort discovery, population health, and data abstraction for clinical trials. EMERSE is now live at three academic medical centers, with additional sites currently working on implementation. In this report, we describe how EMERSE has been used to support cancer research based on a variety of metrics.

METHODS

We identified peer-reviewed publications that used EMERSE through online searches as well as through direct e-mails to users based on audit logs. These logs were also used to summarize use at each of the three sites. Search terms for two of the sites were characterized using the natural language processing tool MetaMap to determine to which semantic types the terms could be mapped.

RESULTS

We identified a total of 326 peer-reviewed publications that used EMERSE through August 2019, although this is likely an underestimation of the true total based on the use log analysis. Oncology-related research comprised nearly one third (n = 105; 32.2%) of all research output. The use logs showed that EMERSE had been used by multiple people at each site (nearly 3,500 across all three) who had collectively logged into the system > 100,000 times. Many user-entered search queries could not be mapped to a semantic type, but the most common semantic type for terms that did match was “disease or syndrome,” followed by “pharmacologic substance.”

CONCLUSION

EMERSE has been shown to be a valuable tool for supporting cancer research. It has been successfully deployed at other sites, despite some implementation challenges unique to each deployment environment.

Kinetic characterisation and inhibitor sensitivity of Candida albicans and Candida auris recombinant AOX expressed in a self-assembled proteoliposome system

Candidemia caused by Candida spp. is a serious threat in hospital settings being a major cause of acquired infection and death and a possible contributor to Covid-19 mortality. Candidemia incidence has been rising worldwide following increases in fungicide-resistant pathogens highlighting the need for more effective antifungal agents with novel modes of action. The membrane-bound enzyme alternative oxidase (AOX) promotes fungicide resistance and is absent in humans making it a desirable therapeutic target. However, the lipophilic nature of the AOX substrate (ubiquinol-10) has hindered its kinetic characterisation in physiologically-relevant conditions. Here, we present the purification and expression of recombinant AOXs from C. albicans and C. auris in a self-assembled proteoliposome (PL) system. Kinetic parameters (Km and Vmax) with respect to ubiquinol-10 have been determined. The PL system has also been employed in dose-response assays with novel AOX inhibitors. Such information is critical for the future development of novel treatments for Candidemia.

Disease Course and Outcomes of COVID-19 Among Hospitalized Patients With Gastrointestinal Manifestations

BACKGROUND & AIMS

Our understanding of outcomes and disease time course of COVID-19 in patients with gastrointestinal (GI) symptoms remains limited. In this study we characterize the disease course and severity of COVID-19 among hospitalized patients with gastrointestinal manifestations in a large, diverse cohort from the Unites States.

METHODS

This retrospective study evaluated hospitalized individuals with COVID-19 between March 11 and April 28, 2020 at two affiliated hospitals in New York City. We evaluated the association between GI symptoms and death, and also explored disease duration, from symptom onset to death or discharge.

RESULTS

Of 2804 patients hospitalized with COVID-19, the 1,084 (38.7%) patients with GI symptoms were younger (aOR for age ≥75, 0.59; 95% CI, 0.45-0.77) and had more co-morbidities (aOR for modified Charlson comorbidity score ≥2, 1.22; 95% CI, 1.01-1.48) compared to those without GI symptoms. Individuals with GI symptoms had better outcomes, with a lower likelihood of intubation (aHR, 0.66; 95% CI, 0.55-0.79) and death (aHR, 0.71; 95% CI, 0.59-0.87), after adjusting for clinical factors. These patients had a longer median disease course from symptom onset to discharge (13.8 vs 10.8 days, log-rank p = .048; among 769 survivors with available symptom onset time), which was driven by longer time from symptom onset to hospitalization (7.4 vs 5.4 days, log-rank P < .01).

CONCLUSION

Hospitalized patients with GI manifestations of COVID-19 have a reduced risk of intubation and death, but may have a longer overall disease course driven by duration of symptoms prior to hospitalization.

Heater-Cooler Devices and Risk of Contamination during Cardiac Surgery

BACKGROUND

 Heater-cooler devices (HCD) have been implicated in a cardiosurgical contamination scenario causing prosthetic valve endocarditis.

AIM

 We characterized contamination of new HCDs and assessed the risk of intraoperative microorganism transmission from the HCD to the operating field.

METHODS

 We initially acquired four new FlexTherm and then four new Maquet HCU40 HCDs and assessed occurrence and speed of microbial contamination (including mycobacteria) assessing swab and water samples from the device. In parallel, we collected repeated samples from different sites in the operating room either by swab sticks or by exposing different sample plates to room air. We also reviewed microbiological results from the hospital and compared them to cardiosurgical wound infections and endocarditis cases. Finally, we simulated cardiosurgical conditions and assessed the devices' ability to expel air to the operative field.

RESULTS

 All new HCDs were clean before first use. Despite authority-mandated decontamination procedures, microbial growth (Fusarium solani, Sphingomonas paucimobilis, Pseudomonas aeruginosa, Mycobacterium chelonae, and gordonae) was identified in all HCDs over time and could not be permanently eliminated. Four of these mircoorganisms were also found in tap water. However, none of the HCD-organisms were found inside the laminar airflow operating area. Importantly, except for P. aeruginosa, none of the HCD organisms were found in patients with surgical wound infections or endocarditis. HCD-expelled air did not rise more than 40 cm above ground.

CONCLUSION

 HCDs cannot be expected to remain sterile despite extensive decontamination procedures. However, airborne transmission of microorganisms directly from the HCD to the operating field appears unlikely.

Using a roller pump for establishing extra-corporal membrane oxygenation (ECMO) - technical considerations for times of crisis

Objective:

The COVID-19 pandemic requires thinking about alternatives to establish ECMO when often-limited hardware resources are exhausted. Heart-lung-machines may potentially be used for ECMO but contain roller pumps as compared to centrifugal pumps in ECMO-circuits. We here tested roller pumps as rescue pump for ECMO-establishment.

Methods:

We set up in vitro circuits on roller pumps from C5 heart-lung-machine with 5 l/minutes flow. In two series, we placed either PVC or silicon tubing for an ECMO circuit into the roller pump. We assessed the mechanical stress on the tubing (aiming to run the pump for at least 1 week), measured the temperature increase generated by the friction and assessed flow characteristics and its measurement in simulated situations resembling tube kinking and suction.

Results:

The roller pumps led to expected and unexpected adverse events. PVC tubing burst between 36 and 78 hours, while silicon tubing lasted for at least 7 days. At 7 days, the silicone tubing showed significant signs of roller pump wear visible on the outside. The inside, however, was free of surface irregularities. Using these tubings in a roller pump led to a remarkable increase in circuit temperature (PVC: +12.0°C, silicone +2.9°C). Kinking or suction on the device caused the expected dramatic flow reduction (as assessed by direct measurement) while the roller pump display continued to show the preset flow. The roller pump is therefore not able to reliably determine the true flow rate.

Conclusion:

Roller pumps with silicone tubing but not PVC tubing may be used for running ECMO circuits. Silicone tubing may endure the roller pump shear forces for up to 1 week. Thus, repeated tubing repositioning may be a solution. Circuit heating and substantial limitations in flow detection should increase attention if clinical use in situations of crisis is considered.

Effect of TSH on Non-Alcoholic Fatty Liver Disease (NAFLD) independent of obesity in children of predominantly Hispanic/Latino ancestry by causal mediation analysis

Background

Nonalcoholic Fatty Liver Disease (NAFLD) is a common co-morbidity of obesity. Elevated TSH levels (eTSH), also associated with obesity, may contribute to the dysmetabolic state that predisposes to NAFLD.

Objective

To assess the relationship between TSH levels and NAFLD in children with biopsy-proven NAFLD compared to controls.

Design and methods

In this retrospective study of children with biopsy-proven NAFLD and age-matched controls, the association of eTSH with NAFLD was investigated and the role of TSH as a mediator between obesity and NAFLD was assessed.

Results

Sixty-six cases and 4067 controls (69.7 vs 59% Hispanic/Latino ancestry, p = 0.1) of the same age range seen in the same time duration at an urban Children’s Hospital were studied. Children with NAFLD were more likely to be male (74.6 vs 39.4%, p < 0.001), have higher modified BMI-z scores (median 2.4 (IQR 1.7) vs 1.9 (IQR 1.7), p < 0.001), and abnormal metabolic parameters (TSH, ALT, HDL-C, non-HDL-C, and TG). Multivariate analyses controlling for age, sex and severity of obesity showed significant association between the 4^th quartile of TSH and NAFLD. Causal mediation analysis demonstrates that TSH mediates 33.8% of the effect of modified BMI-z score on NAFLD. This comprises of 16.0% (OR = 1.1, p = 0.002) caused by the indirect effect of TSH and its interaction with modified BMI-z, and 17.7% (OR = 1.1, p = 0.05) as an autonomous effect of TSH on NAFLD. Overall, 33.8% of the effect can be eliminated by removing the mediator, TSH (p = 0.001).

Conclusions

The association of eTSH and biopsy-proven NAFLD is demonstrated in children of Hispanic/Latino ancestry. Further, a causal mediation analysis implicates an effect of TSH on NAFLD, independent of obesity.

Kinetic and structural characterisation of the ubiquinol-binding site and oxygen reduction by the trypanosomal alternative oxidase

The alternative oxidase (AOX) is a monotopic di‑iron carboxylate protein which acts as a terminal respiratory chain oxidase in a variety of plants, fungi and protists. Of particular importance is the finding that both emerging infectious diseases caused by human and plant fungal pathogens, the majority of which are multi-drug resistant, appear to be dependent upon AOX activity for survival. Since AOX is absent in mammalian cells, AOX is considered a viable therapeutic target for the design of specific fungicidal and anti-parasitic drugs. In this work, we have mutated conserved residues within the hydrophobic channel (R96, D100, R118, L122, L212, E215 and T219), which crystallography has indicated leads to the active site. Our data shows that all mutations result in a drastic reduction in V_max and catalytic efficiency whilst some also affected the K_m for quinol and oxygen. The extent to which mutation effects inhibitor sensitivity was also investigated, with mutation of R118 and T219 leading to a complete loss of inhibitor potency. However, only a slight reduction in IC₅₀ values was observed when R96 was mutated, implying that this residue is less important in inhibitor binding. In silico modelling has been used to provide insight into the reason for such changes, which we suggest is due to disruptions in the proton transfer network, resulting in a reduction in overall reaction kinetics. We discuss our results in terms of the structural features of the ubiquinol binding site and consider the implications of such findings on the nature of the catalytic cycle. SIGNIFICANCE: The alternative oxidase is a ubiquinol oxidoreductase enzyme that catalyses the oxidation of ubiquinol and the reduction of oxygen to water. It is widely distributed amongst the plant, fungal and parasitic kingdoms and plays a central role in metabolism through facilitating the turnover of the TCA cycle whilst reducing ROS production.

Episodes of particle ejection from the surface of the active asteroid (101955) Bennu

Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.

The financial burden of acute odontogenic infections: the South Australian experience

BACKGROUND

Acute odontogenic infections are a common surgical emergency managed by public hospitals in Australia which cause considerable patient morbidity and occasionally, mortality. Despite posing a significant public health burden, Australian data evaluating the cost of the management of these patients are lacking. This study assessed the patient and treatment variables associated with inpatient management of deep odontogenic infections, and their respective financial impact, at a statewide Oral & Maxillofacial service.

METHODS

A retrospective audit was carried out of patients with deep odontogenic infections at our institution, over a 7-year period. The primary outcome was the total cost of admission. Secondary outcomes included treatment received, operating room time, return-to-theatre, length of admission (LOS), and intensive care unit (ICU) use. Cost variables were assessed against the total LOS and ICU use to determine clinical predictors affecting outcome.

RESULTS

Four hundred and sixty two patients met the inclusion criteria. The average cost per patient was $12 228 Australian Dollars. After multivariate analysis, variables most significantly associated with increased cost of care and LOS were high-risk infections with airway compromise, high admission white cell count and age.

CONCLUSION

Hospital-based management of deep-space odontogenic infections engender significant costs compared to early primary care intervention such as a dental extraction ($181/extraction).

Discovery of trypanocidal coumarins with dual inhibition of both the glycerol kinase and alternative oxidase of Trypanosoma brucei brucei

African trypanosomiasis, sleeping sickness in humans or nagana in animals, is a potentially fatal neglected tropical disease and a threat to 65 million human lives and 100 million small and large livestock animals in sub-Saharan Africa. Available treatments for this devastating disease are few and have limited efficacy, prompting the search for new drug candidates. Simultaneous inhibition of the trypanosomal glycerol kinase (TGK) and trypanosomal alternative oxidase (TAO) is considered a validated strategy toward the development of new drugs. Our goal is to develop a TGK-specific inhibitor for coadministration with ascofuranone (AF), the most potent TAO inhibitor. Here, we report on the identification of novel compounds with inhibitory potency against TGK. Importantly, one of these compounds (compound 17) and its derivatives (17a and 17b) killed trypanosomes even in the absence of AF. Inhibition kinetics revealed that derivative 17b is a mixed-type and competitive inhibitor for TGK and TAO, respectively. Structural data revealed the molecular basis of this dual inhibitory action, which, in our opinion, will aid in the successful development of a promising drug to treat trypanosomiasis. Although the EC₅₀ of compound 17b against trypanosome cells was 1.77 µM, it had no effect on cultured human cells, even at 50 µM.-Balogun, E. O., Inaoka, D. K., Shiba, T., Tsuge, C., May, B., Sato, T., Kido, Y., Nara, T., Aoki, T., Honma, T., Tanaka, A., Inoue, M., Matsuoka, S., Michels, P. A. M., Watanabe, Y.-I., Moore, A. L., Harada, S., Kita, K. Discovery of trypanocidal coumarins with dual inhibition of both the glycerol kinase and alternative oxidase of Trypanosoma brucei brucei.

Impact of diagnostic bone biopsies on the management of non-vertebral osteomyelitis: A retrospective cohort study

Optimal antibiotic management of patients with osteomyelitis remains a challenge for many clinicians. Although image-guided bone biopsy (IGB) remains the gold standard, its role in confirming diagnosis and guiding antibiotic management is not clear in patients with non-vertebral osteomyelitis.To determine the diagnostic yield of IGB and its impact on antibiotic management in non-vertebral osteomyelitis.Retrospective cohort study.Urban academic medical center.Patients admitted for non-vertebral osteomyelitis who underwent image-guided bone biopsy.Primary outcomes were microbiologic and histopathological results. We evaluated the impact of IGB on clinician-initiated changes in antibiotic regimen before and after biopsy.We evaluated 203 bone biopsies in 185 patients with clinical suspicion of osteomyelitis. 79% of patient received antibiotics prior to biopsy. Bone cultures were positive in 28% and histopathology confirmed osteomyelitis in 29%, but concordance was poor. Furthermore, clinical suspicion of infection was much higher, given that 68% received empiric antibiotics. Leukocytosis was significantly associated with positive cultures in multivariate analysis. There was no statistically significant correlation between antibiotic management and bone culture results. When culture yielded an organism, empiric regimens were kept the same, broadened or narrowed with equal frequency; targeted regimens were chosen only in 4 cases. Despite negative cultures in 98/138 cases having received empiric treatment, antibiotics were discontinued in only 8 cases. Even when empiric treatment was not given, negative cultures did not dissuade clinicians from eventual antibiotic use in a significant number of cases (17/48). In 46/71 patients whose final regimen included vancomycin, there was no evidence of current or past infection with MRSA.In patients with non-vertebral osteomyelitis, the diagnostic yield of image-guided bone biopsy is low, and clinicians frequently make decisions regarding antibiotic management that are not aligned with culture results.

Timing of HPV16-E6 antibody seroconversion before OPSCC: findings from the HPVC3 consortium

BACKGROUND

Human papillomavirus type 16 (HPV16)-E6 antibodies are detectable in peripheral blood before diagnosis in the majority of HPV16-driven oropharyngeal squamous cell carcinoma (OPSCC), but the timing of seroconversion is unknown.

PATIENTS AND METHODS

We formed the HPV Cancer Cohort Consortium which comprises nine population cohorts from Europe, North America and Australia. In total, 743 incident OPSCC cases and 5814 controls provided at least one pre-diagnostic blood sample, including 111 cases with multiple samples. Median time between first blood collection and OPSCC diagnosis was 11.4 years (IQR = 6-11 years, range = 0-40 years). Antibodies against HPV16-E6 were measured by multiplex serology (GST fusion protein based Luminex assay).

RESULTS

HPV16-E6 seropositivity was present in 0.4% of controls (22/5814; 95% CI 0.2% to 0.6%) and 26.2% (195/743; 95% CI 23.1% to 29.6%) of OPSCC cases. HPV16-E6 seropositivity increased the odds of OPSCC 98.2-fold (95% CI 62.1-155.4) in whites and 17.2-fold (95% CI 1.7-170.5) in blacks. Seropositivity in cases was more frequent in recent calendar periods, ranging from 21.9% pre-1996 to 68.4% in 2005 onwards, in those with blood collection near diagnosis (lead time <5 years). HPV16-E6 seropositivity increased with lead time: 0.0%, 13.5%, 23.7%, and 38.9% with lead times of >30 years (N = 24), 20-30 years (N = 148), 10-20 years (N = 228), and <10 years (N = 301 cases) (p-trend < 0.001). Of the 47 HPV16-E6 seropositive cases with serially-collected blood samples, 17 cases seroconverted during follow-up, with timing ranging from 6 to 28 years before diagnosis. For the remaining 30 cases, robust seropositivity was observed up to 25 years before diagnosis.

CONCLUSIONS

The immune response to HPV16-driven tumorigenesis is most often detectable several decades before OPSCC diagnosis. HPV16-E6 seropositive individuals face increased risk of OPSCC over several decades.

SAT-LB015 Association of Subclinical Hypothyroidism with Nonalcoholic Fatty Liver in Children with Overweight and Obesity

Background: Non-Alcoholic Fatty Liver Disease (NAFLD) is a common co-morbidity with obesity. Recent studies in adults with obesity have shown an association between subclinical hypothyroidism (SH) and NAFLD. Few studies of children from Europe have also assessed the association of SH with NAFLD diagnosed by ultrasound (1). Little is known about this association in children from underrepresented minorities in the US, especially in children of Latina ancestry and those with biopsy-proven NAFLD. Thyroid hormone impacts major metabolic pathways and overt hypothyroidism has been associated with insulin resistance and dyslipidemia. Aim: To assess the prevalence of SH in children of primarily Latina ancestry with biopsy-proven NAFLD as compared to children of the same age range visiting the clinic during the same years. Methods: We performed a retrospective study of 4363 children aged 5-19 years seen in an urban ambulatory care setting primarily serving children of Latina ancestry (> 80%). Sixty-three of these children had NAFLD proven by liver biopsy. Results of thyroid, liver, and lipid studies as well as demographic data were extracted from the electronic health record. A descriptive evaluation was performed. TSH values were divided into quartiles: Q1: TSH ≤1.07 mIU/L, Q2: TSH 1.07-1.59 mIU/L, Q3: TSH 1.59-2.36 mIU/L, Q4: TSH ≥ 2.36 mIU/L. The association of TSH quartiles with NAFLD was assessed by univariate analysis and multivariate logistic regression adjusting for age, gender, and severity of obesity. All analyses were performed in R statistical software. Results: There was a higher proportion of boys (74% vs. 40%, p < 0.001) in those with NAFLD, and they were younger (12.9±3.1 vs. 14.7±3.7 years, p < 0.001). Children with biopsy-proven NAFLD had significantly higher BMI, TSH, and ALT when compared to those without NAFLD (TSH, cases: 2.9 ± 1.2 mIU/L, controls: 1.9 ± 1.2 mIU/L, p<0.0001). The proportion of children with abnormal ALT, AST, and GGT was significantly higher in those with NAFLD compared to the controls (p < 0.001). They also had a higher proportion of abnormal total, HDL, and non-HDL cholesterol (p = 0.01). The odds of having NAFLD was statistically higher for children in Q3 (OR 5.07, p=0.003) and Q4 (OR 8.48, p<0.0001) of TSH, compared to those in Q1. After adjusting for age, gender, and severity of obesity, biopsy-proven NAFLD approached significantly higher odds (2.7, p = 0.07) in Q3 and was statistically significant in Q4 (OR= 4.0, p=0.0113). Conclusion: Children of Latina ancestry with NAFLD diagnosed by histology are at higher odds of having SH. Based on the results of this study, we hypothesize that thyroid dysfunction plays a mediator role in the development of NAFLD and should be investigated in all children with obesity. References: 1) PMID 26877190. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

Abstract P1-08-11: The impact of existing comorbidities on survival disparities among women diagnosed with invasive breast cancer

Missouri is one of many states in the US burdened by high rates of mortality from female breast cancer (BC) as well as comorbidities such as Type-2 diabetes, cardiovascular disease (CVD), and hypertension. These comorbidity rates are higher among vulnerable populations including individuals in poverty and/or living in rural areas, African Americans, and the elderly. There is evidence that women with comorbidities at the time of BC diagnosis have a worse prognosis. We hypothesize that the co-existence of comorbidities is likely to impact survival and may contribute to survival disparities observed among women diagnosed with BC from these vulnerable populations.

Objective: To examine whether the number and/or type of comorbidity at BC diagnosis is associated with higher BC and all-cause mortality among women diagnosed with invasive BC in Missouri between 2004 and 2012.

Methods: Women age 18+ diagnosed with BC in Missouri during 2004–2012 were identified from the Missouri Cancer Registry. These data were then merged with hospital discharge data from the Missouri Patient Abstract System. Associations were evaluated in all women and by race, neighborhood poverty level, rural/urban residence, and age at diagnosis. A comorbidity score was constructed to account for the number of comorbidities (Type-2 diabetes, hypertension, and CVD) identified for each individual. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox proportional hazards regression models, adjusting for age at diagnosis, race, tumor hormone receptor status, stage, BC treatment, and rural/urban residence. Models were further stratified by race, poverty level, rural/urban residence, and age group.

Results: A total of 31,133 women with incident invasive BC and with comorbidity data at the time of BC diagnosis were included in the analysis. After a median follow-up time of 79 months, 9,912 deaths occurred, of which 4,900 deaths were due to BC. Increasing number of comorbidities was significantly associated with BC mortality (ptrend &lt; 0.001). BC mortality (HR, 1.33; 95% CI 1.19-1.49) and all-cause mortality (HR, 1.51; 90% CI 1.32-1.61) were significantly higher in women with ≥2 comorbidities. CVD accounted for the largest increase in BC mortality (HR, 1.36; 95% CI 1.19-1.55). In stratified analyses, we did not observe significant differences in associations by race, poverty, rural/urban residence, or age; however, there was a statistically significant interaction with age when modeled as a continuous measure, comorbidity score, and risk of mortality outcomes (p&lt; 0.001). White women with all 3 comorbidities had the highest risk of death (BC-specific: HR, 1.95; all-cause: HR, 2.28). Women in rural areas with ≥2 comorbidities were 1.78 times more likely to die of BC while women living in the metro with all 3 comorbidities were almost 2 times more likely to die of any cause.

Conclusion: Our results demonstrate the negative impact that comorbidities such as diabetes, CVD, and hypertension can have on BC and overall mortality in a diverse group of BC patients diagnosed and treated in Missouri. The data produced from this study can be utilized to identify and implement targeted preventive strategies to improve the quality of life and survival of BC patients.

Citation Format: Connor AE, May B, Schmaltz CL, Jackson-Thompson J, Visvanathan K. The impact of existing comorbidities on survival disparities among women diagnosed with invasive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-08-11.

Abstract P4-10-06: Factors impacting the accuracy of self-reported breast procedures among women with and without breast cancer

Background: Clinical/epidemiologic observational studies frequently rely on participants' recall for information about breast procedures. However, there is limited data on the accuracy of self-reported breast procedures. To address this knowledge gap and inform future study design and collection and interpretation of similar data, we investigated the impact of type, diagnosis, age, time, and other patient characteristics on the accuracy of self-report in a prospective cohort.

Methods: All benign breast biopsies, lumpectomies, and mastectomies for breast cancer treatment among women enrolled in the BOSS Cohort, a prospective study of women and men with a familial risk of breast/ovarian cancer, were identified. Study staff obtained pathology reports for 93% of women from self-reported breast procedure locations. For this analysis, we focused on 577 women who had at least one ascertained pathology report, and who self-reported at least one breast procedure at baseline. We estimated the percentage of self-reports (95% confidence interval (CI)) with matching pathology report within 6 months (+/- 6 months), and agreement between self-reported procedures and pathology-confirmed diagnoses (normal/benign vs. atypical hyperplasia vs. LCIS, and DCIS vs. invasive cancer) with the Kappa statistic. We also examined predictors of an accurate biopsy self-report, including age at baseline, personal and family history of breast cancer, educational attainment, and time between biopsy and baseline, using logistic regression models.

Results: At baseline, 158 women reported having at least one benign biopsy, 193 women reported having a lumpectomy for cancer treatment, and 174 women reported having a mastectomy for cancer treatment. The median time between biopsy, lumpectomy, mastectomy, and baseline was 9 years, 2 years, and 2 years, respectively. Fifty-seven percent (95% CI: 49-64.5%) of benign biopsy self-reports, 90.7% (95% CI: 85.6-94.1%) of lumpectomy self-reports, and 85.1% (95% CI: 78.9-89.7%) of mastectomy self-reports had a matching pathology report within 6 months. Further diagnostic agreement was moderate for biopsies, lumpectomies, and mastectomies with Kappa statistics of 0.65, 0.66, 0.65, respectively. Age at baseline (p-interaction =0.01) and time (p-interaction = 0.03) were independent and joint predictors of accurate biopsy self-reports. Women less than 49 years old had the largest reduction in odds of having an accurate self-report (26%) for every additional year between biopsy and baseline [adjusted odds ratio = 0.74 (95% CI: 0.63-0.88)]. Similarly, women with a biopsy within 4 years prior to baseline had a 10% reduction in the odds of having an accurate self-report with increasing age [adjusted odds ratio = 0.9 (95% CI: 0.84-0.97)].

Conclusions: In this highly-educated cohort, the overall accuracy of self-report of benign biopsies was only modest, and the accuracy of self-report of lumpectomies and mastectomies was lower than expected. This study suggests that age at baseline and time between procedure and baseline are important predictors of accuracy of self-report and should be considered when utilizing self-reported information. Furthermore, where possible, prospective collection of breast procedure data should be prioritized.

Citation Format: Schaeffer ML, May B, Cimino-Mathews A, Orellana M, McCullough M, Hogan B, Armstrong D, Visvanathan K. Factors impacting the accuracy of self-reported breast procedures among women with and without breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-10-06.

Reactions of a Polyhalide Ionic Liquid with Copper, Silver, and Gold

The reactions of copper, silver, and gold with the imidazolium‐based polyhalide ionic liquid (IL) [C₆C₁Im][Br₂I] were investigated by using X‐ray photoelectron spectroscopy (XPS), weight‐loss measurements, and gas‐phase mass spectrometry. All three Group 11 metals are strongly corroded by the IL at moderate temperatures to give a very high content of dissolved Cu^I, Ag^I, and Au^I species. The IL–metal solutions are stable against contact with water and air. The replacement of imidazolium with inorganic sodium cations decreased metal corrosion rates by orders of magnitude. Our results clearly indicate metal oxidation by iodide from dibromoiodide anions to form molecular iodine and anionic [Br‐M^I‐Br]⁻ (M=Cu, Ag, Au) complexes stabilized by imidazolium counterions. From experiments with a trihalide IL with imidazolium methylated at the 2‐position, we ruled out the formation of imidazole–carbene as a cause of the observed corrosion. In contrast to Group 11 metals, molybdenum is inert against the trihalide IL, which is attributed to surface passivation.

Cover Feature: Reactions of a Polyhalide Ionic Liquid with Copper, Silver, and Gold (ChemistryOpen 1/2019)

The Cover Feature shows how coinage metals such as gold, silver, and copper are rapidly dissolved under mild and safe conditions by the ionic liquid 1‐hexyl‐3‐methylimidiazolim dibromoiodide ([C₆C₁Im][Br₂I]), forming metal(I)–dibromo anionic complexes together with molecular iodine, as proven by X‐ray photoelectron spectroscopy, etching experiments, and gas‐phase analysis. Trihalide ionic liquids are shown to be promising candidates for precious‐metal etching and leaching media, and may also open new possibilities for Au(I) catalysis. More information can be found in the Full Paper by F. Maier and co‐workers on page 15 in Issue 1, 2019 (DOI: 10.1002/open.201800149).

Core Biopsy and FNA: A Comparison of Diagnostic Yield in Lymph Nodes of Different Ultrasound Determined Malignant Potential

Background: The tissue diagnosis of lymphoma and metastases is commonly obtained from affected lymph nodes. The lymph nodes chosen for biopsy are often the consequence of their appearance on ultrasound, which determines their risk of malignancy. Two frequently used percutaneous sampling techniques are core biopsy and fine needle aspiration (FNA). While core biopsy obtains a larger tissue sample and provides a degree of architectural information, FNA is considered less invasive and has the advantage of immediate confirmation of adequacy by the attending cytologist. Anecdotally, core biopsy is more commonly used when a lymph node is suspected of harboring neoplasia, however a feature of malignancy is hypercellularity, which theoretically should increase the diagnostic yield of FNA. Aim: The aim of this project was to compare the diagnostic capability of FNA and core biopsy in lymph nodes of different malignant potential, as defined by ultrasound, and determine if the radiologic appearance can guide clinicians in their choice of sampling technique. The project also reviewed the role of clinical experience in both the choice of sampling technique and diagnostic yield. Methods: Retrospective study of percutaneous lymph node biopsies performed at a large tertiary hospital between July 2016 and March 2018. The associated ultrasounds were reviewed and the lymph nodes were classified as high or low risk of malignancy by their sonographic appearance. The end point for analysis was the capacity for FNA or core biopsy to provide a definitive diagnosis. The diagnostic yield was then separately assessed for lymph nodes of high and low malignant potential. The effect of clinical experience on diagnostic yield was also examined, by comparing the outcomes of radiology consultants and radiology trainees. Results: 296 lymph node biopsies were reviewed and statistical analysis was performed using logistic regression analysis. Core biopsy, in comparison with FNA, was used twice as often in lymph nodes of high malignant potential, supporting the aforementioned anecdotal evidence. Core biopsy demonstrated superior diagnostic yield in comparison with FNA, providing a diagnostic sample 45% ( P = 0.313) more often in low-risk lymph nodes and 209% ( P = < 0.05) more often in high-risk lymph nodes. Consultant radiologists used FNA 81% more often than core biopsy in lymph nodes of high malignant potential, while radiology trainees used core biopsy 104% more often than FNA in the same group. In high-risk lymph nodes, trainees were 117% ( P = 0.105) more likely to obtain a diagnostic sample than consultants. Conclusion: Core biopsy is superior to FNA in the tissue sampling of lymph nodes regardless of ultrasound determined risk of malignancy. Biopsies obtained by radiology trainees provided a diagnosis twice as often as those obtained by radiology consultants. This appeared to be the consequence of consultant preference for FNA over core biopsy.

Narrowing the wingless-2 mutation to a 227 kb candidate region on chicken chromosome 12

Wingless-2 (wg-2) is an autosomal recessive mutation in chicken that results in an embryonic lethal condition. Affected individuals exhibit a multisystem syndrome characterized by absent wings, truncated legs, and craniofacial, kidney, and feather malformations. Previously, work focused on phenotype description, establishing the autosomal recessive pattern of Mendelian inheritance and placing the mutation on an inbred genetic background to create the congenic line UCD Wingless-2.331. The research described in this paper employed the complementary tools of breeding, genetics, and genomics to map the chromosomal location of the mutation and successively narrow the size of the region for analysis of the causative element. Specifically, the wg-2 mutation was initially mapped to a 7 Mb region of chromosome 12 using an Illumina 3 K SNP array. Subsequent SNP genotyping and exon sequencing combined with analysis from improved genome assemblies narrowed the region of interest to a maximum size of 227 kb. Within this region, 3 validated and 3 predicted candidate genes are found, and these are described. The wg-2 mutation is a valuable resource to contribute to an improved understanding of the developmental pathways involved in chicken and avian limb development as well as serving as a model for human development, as the resulting syndrome shares features with human congenital disorders.

Antibiotic resistance in severe odontogenic infections of the South Australian population: a 9-year retrospective audit

BACKGROUND

The aims of this study were to evaluate the microbiological trends in severe odontogenic infections requiring hospital admission in the South Australian Oral and Maxillofacial Surgery Unit. Rates of antibiotic resistance to empirical antibiotic regimens were determined to quantify the clinical implications of antibiotic-resistant odontogenic infections.

METHODS

A retrospective case audit was performed on all odontogenic infections admitted to the Royal Adelaide Hospital over a 9-year period. Data was collected regarding demographics, microbiological culture and sensitivity results, and clinical outcome variables.

RESULTS

Of a total of 672 patients, microbiology data was available for 447 cases. Penicillin-resistant organisms were identified in 10.8% of patients, who required a significantly longer length of hospital admission (mean, 9.93 days) and higher rates of non-response to initial surgical therapy (40%).

CONCLUSIONS

There were moderate rates of antibiotic-resistant odontogenic infections within the South Australian population. Patients within this subgroup demonstrate markedly poorer clinical outcomes. Effective treatment of odontogenic infections involves early operative intervention, with adjunctive use of appropriate antibiotic therapy that involves close monitoring of response to removal of the cause and use of first-line antibiotic agents. Cases that fail to respond require urgent specialist review in order to reduce morbidity and mortality outcomes.

Time-dependent changes in the growth of ultrathin ionic liquid films on Ag(111)

Time dependent changes of IL film morphology depend on their molecular structure.

Various amounts of the ionic liquids (ILs) [C₁C₁Im][Tf₂N] and [C₈C₁Im][Tf₂N] were deposited in vacuo by physical vapour deposition (PVD) on single crystalline Ag(111) at room temperature and subsequently monitored by angle-resolved X-ray photoelectron spectroscopy (ARXPS) as a function of time. For very low coverages of up to one closed molecular layer, an initial wetting layer was rapidly formed for both ILs. Deposition of higher amounts of [C₁C₁Im][Tf₂N] revealed an initial three-dimensional film morphology. On the time scale of hours, characteristic changes of the XPS signals were observed. These are interpreted as island spreading and a transformation towards a nearly two dimensional [C₁C₁Im][Tf₂N] film as the final state. In contrast, a film morphology close to 2D was found from the very beginning for [C₈C₁Im][Tf₂N] deposited on Ag(111) demonstrating the influence of the alkyl chain length on the growth kinetics. These studies also highlight the suitability of time-resolved ARXPS for the investigation of IL/solid interfaces, which play a crucial role in IL thin film applications such as in catalysis, sensor, lubrication, and coating technologies.

Utility of Diagnostic Bone Biopsies in the Management of Osteomyelitis Through Retrospective Analysis: How Golden Is This Gold Standard?

Background

Bone biopsy is considered the gold standard for diagnosis and treatment of osteomyelitis (OM), but few studies have investigated the extent to which it influences antimicrobial therapy in non-vertebral bones. The purpose of this study was to evaluate clinician-initiated changes to empiric antimicrobial therapy after obtaining bone biopsy results. A secondary aim was to identify predictors of a positive bone culture.

Methods

We retrospectively reviewed all cases of non-vertebral OM in patients who underwent image-guided bone biopsies between 2009 and 2016. Data on pathologic and microbiologic yield were collected and logistic regression was used to determine potential factors affecting the microbiologic yield. Post-biopsy empiric antibiotics and final antibiotics were compared with determine if there was a change in antibiotic treatment after biopsy results were reported.

Results

We evaluated 203 bone biopsies in 185 patients. Samples from 115 (57%) cases were sent to pathology, of which 33 (29%) confirmed OM. All samples were sent to microbiology and 57 (28%) yielded a positive result. Diabetes (OR=2.39, P = 0.021) and white blood cell count (OR=1.13, P = 0.006) were significantly associated with positive bone cultures in multivariate analyses. There was no association between positive cultures and number of samples cultured, needle size, prior antibiotic use, or antibiotic-free days. Post-biopsy empiric antibiotics were given in 138 (68%) cases. Therapy was narrowed to target specific organisms in seven cases and changed due to inadequate empiric treatment in three cases. Targeted therapy was initiated in 4/65 cases, in which empiric antibiotics had been initially withheld. While final antibiotics were withheld in 38/146 with negative bone cultures, empiric antibiotics were discontinued in only eight cases.

Conclusion

In patients with non-vertebral OM, bone biopsy cultures rarely yielded results that necessitated changes in antibiotic management. Identified bone organisms were treated by empiric therapy in most patients. While bone biopsy remains the gold standard diagnostic test for OM, further work is needed to identify patients whose management may be impacted by this procedure.

Disclosures

All authors: No reported disclosures.

Surface-Induced Changes in the Thermochromic Transformation of an Ionic Liquid Cobalt Thiocyanate Complex

We demonstrate that a thermodynamic complex equilibrium within an ionic liquid film can be significantly influenced by the presence of the liquid-vacuum interface. Using surface-sensitive X-ray photoelectron spectroscopy, we find that the temperature-driven transition from the blue-colored tetrahedral [Co(II) (NCS)₄]^2- to the red-colored octahedral [Co(II) (NCS)₆]^4- complex already occurs within the outermost nanometers at around +4 °C as compared with -25 °C in the bulk. This thermochromic transformation in the near-surface region goes along with a loss in preferential surface orientation of free [SCN]^- anions and with a pronounced decrease in the complex density; both effects are attributed to the formation of a weakly bound solvation shell around the [Co(II) (NCS)₆]^4- anion, leading to an effective complex dilution. Our results are not only relevant for high-surface area thin film systems, such as in sensor and catalysis applications, but also shed light on the role of ionic liquid surfaces in particular and liquid surfaces in general.

Switching adsorption and growth behavior of ultrathin [C2C1Im][OTf] films on Au(111) by Pd deposition

Combining in vacuo deposition of ultrathin ionic liquid (UTIL) films with angle-resolved X-ray photoelectron spectroscopy (ARXPS), we demonstrate that by deposition of submonolayer amounts of Pd onto Au(111) the initial growth mode of the ionic liquid (IL) 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([C₂C₁Im][OTf]) can be switched from three-dimensional (3D) to two-dimensional (2D) growth, that is, from non-wetting to wetting. On clean Au(111), pronounced 3D growth occurs on top of an initially formed 2D wetting layer with cations and anions next to each other in a checkerboard arrangement. After pre- or postdeposition of only 0.7 ML Pd, two-dimensional layer-by-layer growth is found, which is attributed to strong attractive interactions between [C₂C₁Im][OTf] and surface Pd. For Pd post deposition onto the IL, the ARXPS data revealed particularly strong interactions between the dialkylimidazolium cation and Pd atoms, which considerably reduce the regular surface alloying of Pd with the Au substrate stabilizing Pd at the metal surface. In the context of heterogeneous catalysis using the SCILL (solid catalyst coated with ionic liquid layer) concept, these results directly provide a possible explanation on the molecular level for the beneficial influence of the IL layer in case of heterogeneous metal alloy catalysts.

A Self-Assembled Respiratory Chain that Catalyzes NADH Oxidation by Ubiquinone-10 Cycling between Complex I and the Alternative Oxidase

Complex I is a crucial respiratory enzyme that conserves the energy from NADH oxidation by ubiquinone‐10 (Q₁₀) in proton transport across a membrane. Studies of its energy transduction mechanism are hindered by the extreme hydrophobicity of Q₁₀, and they have so far relied on native membranes with many components or on hydrophilic Q₁₀ analogues that partition into membranes and undergo side reactions. Herein, we present a self‐assembled system without these limitations: proteoliposomes containing mammalian complex I, Q₁₀, and a quinol oxidase (the alternative oxidase, AOX) to recycle Q₁₀H₂ to Q₁₀. AOX is present in excess, so complex I is completely rate determining and the Q₁₀ pool is kept oxidized under steady‐state catalysis. The system was used to measure a fully‐defined K_M value for Q₁₀. The strategy is suitable for any enzyme with a hydrophobic quinone/quinol substrate, and could be used to characterize hydrophobic inhibitors with potential applications as pharmaceuticals, pesticides, or fungicides.

Expression and crystallization of the plant alternative oxidase

The alternative oxidase (AOX) is an integral monotopic membrane protein located on the inner surface of the inner mitochondrial membrane. Branching from the traditional respiratory chain at the quinone pool, AOX is responsible for cyanide-resistant respiration in plants and fungi, heat generation in thermogenic plants, and survival of parasites, such as Trypanosoma brucei, in the human host. A recently solved AOX structure provides insight into its active site, thereby facilitating rational phytopathogenic and antiparasitic drug design. Here, we describe expression of recombinant AOX using two different expression systems. Purification protocols for the production of highly pure and stable AOX protein in sufficient quantities to facilitate further kinetic, biophysical, and structural analyses are also described.

Developing major histocompatibility markers in a species of concern: the Sacramento perch Archoplites interruptus

Primers targeting two non-neutral major histocompatibility complex (mhc) II β genes were developed and assayed across several disjoint Sacramento perch Archoplites interruptus sampling locations. Variability at the two mhc loci among sampling stocks strongly correlated to previous estimates with neutral markers, suggesting that the effect of genetic drift was not limited to neutrally evolving regions of the genome. The novel mhc primers will help develop admixture schemes in A. interruptus captive breeding programmes and will increase the success of future reintroductions of this species of concern.

Probing the ubiquinol-binding site of recombinant Sauromatum guttatum alternative oxidase expressed in E. coli membranes through site-directed mutagenesis

In the present paper we have investigated the effect of mutagenesis of a number of highly conserved residues (R159, D163, L177 and L267) which we have recently shown to line the hydrophobic inhibitor/substrate cavity in the alternative oxidases (AOXs). Measurements of respiratory activity in rSgAOX expressed in Escherichia coli FN102 membranes indicate that all mutants result in a decrease in maximum activity of AOX and in some cases (D163 and L177) a decrease in the apparent Km (O2). Of particular importance was the finding that when the L177 and L267 residues, which appear to cause a bottleneck in the hydrophobic cavity, are mutated to alanine the sensitivity to AOX antagonists is reduced. When non-AOX anti-malarial inhibitors were also tested against these mutants widening the bottleneck through removal of isobutyl side chain allowed access of these bulkier inhibitors to the active-site and resulted in inhibition. Results are discussed in terms of how these mutations have altered the way in which the AOX's catalytic cycle is controlled and since maximum activity is decreased we predict that such mutations result in an increase in the steady state level of at least one O2-derived AOX intermediate. Such mutations should therefore prove to be useful in future stopped-flow and electron paramagnetic resonance experiments in attempts to understand the catalytic cycle of the alternative oxidase which may prove to be important in future rational drug design to treat diseases such as trypanosomiasis. Furthermore since single amino acid mutations in inhibitor/substrate pockets have been found to be the cause of multi-drug resistant strains of malaria, the decrease in sensitivity to main AOX antagonists observed in the L-mutants studied in this report suggests that an emergence of drug resistance to trypanosomiasis may also be possible. Therefore we suggest that the design of future AOX inhibitors should have structures that are less reliant on the orientation by the two-leucine residues. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.