Mycobacterium ulcerans challenge strain selection for a Buruli ulcer controlled human infection model.

Critical scientific questions remain regarding infection with Mycobacterium ulcerans, the organism responsible for the neglected tropical disease, Buruli ulcer (BU). A controlled human infection model has the potential to accelerate our knowledge of the immunological correlates of disease, to test prophylactic interventions and novel therapeutics. Here we present microbiological evidence supporting M. ulcerans JKD8049 as a suitable human challenge strain. This non-genetically modified Australian isolate is susceptible to clinically relevant antibiotics, can be cultured in animal-free and surfactant-free media, can be enumerated for precise dosing, and has stable viability following cryopreservation. Infectious challenge of humans with JKD8049 is anticipated to imitate natural infection, as M. ulcerans JKD8049 is genetically stable following in vitro passage and produces the key virulence factor, mycolactone. Also reported are considerations for the manufacture, storage, and administration of M. ulcerans JKD8049 for controlled human infection.

Prevalence, risk factors and outcomes of secondary infections among hospitalised patients with COVID-19 or post-COVID-19 conditions in Victoria, 2020-2023.

OBJECTIVES: Estimates of secondary infections are variedly reported, with few studies done in Australia. We investigated the occurrence and impact of secondary infections complicating COVID-19 and post-COVID-19 admissions in Victoria, Australia, 2020-2023. METHODS: We used linked population-wide datasets and ICD-10 codes to identify and estimate occurrence of secondary infections. Using hospital/ICU length of stay (LOS) in negative binomial regression, and mortality, we examined the impact of secondary infections. RESULTS: Secondary infections were identified in 6·9% (13,467/194,660) of COVID-19 and post-COVID-19 admissions; 6·0% (11,651/194,660) bacterial, 0·9% (1,691/194,660) viral, and 0·2% (385/194,660) fungal. Prevalence was highest during Pre-Delta (10.4%) and Omicron-BA2 (8.1%) periods. Sepsis and pneumonia were the most reported syndromes; occurrence of sepsis declined gradually over time. The odds of secondary infections were higher among the ≥70-year-olds (adjusted odds ratio(aOR):3·76 (95%CI: 3·43-4·14; vs 20-29-year-olds), individuals with chronic conditions (aOR:3·15; 95%CI: 2·88-3·45; vs those without), the unvaccinated (aOR:1·59; 95%CI: 1·45-1·75) and the lowest socio-economic group (aOR:1·12; 95%CI: 1·05-1·19). Patients with secondary infections had 2·43 times longer hospital LOS, and 9·60 times longer ICU LOS compared to those without. Mortality risk was 2·17 times higher in those with secondary infections. CONCLUSION: Secondary infections occurred in 69 per 1000 COVID-19 associated hospital admissions in Victoria, mostly in high-risk groups, and were associated with severe outcomes.

Syngeneic murine models with distinct immune microenvironments represent subsets of human intrahepatic cholangiocarcinoma.

BACKGROUND & AIMS: Cholangiocarcinoma (CCA) is a poorly immunogenic malignancy associated with limited survival. Syngeneic immunocompetent mouse models of CCA are an essential tool to elucidate the tumor immune microenvironment (TIME), understand mechanisms of tumor immune evasion, and test novel immunotherapeutic strategies. The scope of this study was to develop and characterize immunocompetent CCA models with distinct genetic drivers, and correlate tumor genomics, immunobiology, and therapeutic response. METHODS: A multifaceted approach including scRNA-seq, CITE-seq, whole exome and bulk RNA sequencing was employed. FDA-approved PD-1/PD-L1 antibodies were tested in humanized PD-1/PD-L1 mice (HuPD-H1). RESULTS: A genetic mouse model of intrahepatic CCA (iCCA) driven by intrabiliary transduction of Fbxw7ΔF/Akt that mimics human iCCA was generated. From the Fbxw7ΔF/Akt tumors, a murine cell line (FAC) and syngeneic model with genetic and phenotypic characteristics of human iCCA were developed. Established SB1 (YAPS127A/Akt) and KPPC (KrasG12Dp53L/L) models were compared to the FAC model. Although the models had transcriptomic similarities, they had substantial differences as well. Mutation patterns of FAC, SB1, and KPPC cells matched different mutational signatures in Western and Japanese CCA patient cohorts. KPPC tumors had a high tumor mutation burden. FAC tumors had a T cell-infiltrated TIME, while SB1 tumors had a preponderance of suppressive myeloid cells. FAC, SB1, and KPPC tumors matched different immune signatures in human iCCA cohorts. Moreover, FAC, SB1, and KPPC tumor-bearing HuPD-H1 mice displayed differential responses to nivolumab or durvalumab. CONCLUSIONS: Syngeneic iCCA models display a correlation between tumor genotype and TIME phenotype, with differential responses to FDA-approved immunotherapies. This study underscores the importance of leveraging multiple preclinical models to understand responses to immunotherapy in different genetic subsets of human CCA. IMPACT AND IMPLICATIONS: Understanding the relationship between tumor genotype and the phenotype of the immune microenvironment is an unmet need in cholangiocarcinoma (CCA). Herein, we use syngeneic murine models of intrahepatic CCA with different genetic drivers to demonstrate a correlation between tumor genotype and immune microenvironment phenotype in murine models, which is associated with differential responses to FDA-approved immunotherapies. This information will help guide other preclinical studies. Additionally, it emphasizes that immune checkpoint inhibition in patients with CCA is not a "one-size-fits-all" approach. Our observations suggest that, as for targeted therapies, patients should be stratified and selected for treatment according to their tumor genetics.

PTEN deficiency induces an extrahepatic cholangitis-cholangiocarcinoma continuum via aurora kinase A in mice.

BACKGROUND & AIMS: The PTEN-AKT pathway is frequently altered in extrahepatic cholangiocarcinoma (eCCA). We aimed to evaluate the role of PTEN in the pathogenesis of eCCA and identify novel therapeutic targets for this disease. METHODS: The Pten gene was genetically deleted using the Cre-loxp system in biliary epithelial cells. The pathologies were evaluated both macroscopically and histologically. The characteristics were further analyzed by immunohistochemistry, reverse-transcription PCR, cell culture, and RNA sequencing. Some features were compared to those in human eCCA samples. Further mechanistic studies utilized the conditional knockout of Trp53 and Aurora kinase A (Aurka) genes. We also tested the effectiveness of an Aurka inhibitor. RESULTS: We observed that genetic deletion of the Pten gene in the extrahepatic biliary epithelium and peri-ductal glands initiated sclerosing cholangitis-like lesions in mice, resulting in enlarged and distorted extrahepatic bile ducts in mice as early as 1 month after birth. Histologically, these lesions exhibited increased epithelial proliferation, inflammatory cell infiltration, and fibrosis. With aging, the lesions progressed from low-grade dysplasia to invasive carcinoma. Trp53 inactivation further accelerated disease progression, potentially by downregulating senescence. Further mechanistic studies showed that both human and mouse eCCA showed high expression of AURKA. Notably, the genetic deletion of Aurka completely eliminated Pten deficiency-induced extrahepatic bile duct lesions. Furthermore, pharmacological inhibition of Aurka alleviated disease progression. CONCLUSIONS: Pten deficiency in extrahepatic cholangiocytes and peribiliary glands led to a cholangitis-to-cholangiocarcinoma continuum that was dependent on Aurka. These findings offer new insights into preventive and therapeutic interventions for extrahepatic CCA. IMPACT AND IMPLICATIONS: The aberrant PTEN-PI3K-AKT signaling pathway is commonly observed in human extrahepatic cholangiocarcinoma (eCCA), a disease with a poor prognosis. In our study, we developed a mouse model mimicking cholangitis to eCCA progression by conditionally deleting the Pten gene via Pdx1-Cre in epithelial cells and peribiliary glands of the extrahepatic biliary duct. The conditional Pten deletion in these cells led to cholangitis, which gradually advanced to dysplasia, ultimately resulting in eCCA. The loss of Pten heightened Akt signaling, cell proliferation, inflammation, fibrosis, DNA damage, epigenetic signaling, epithelial-mesenchymal transition, cell dysplasia, and cellular senescence. Genetic deletion or pharmacological inhibition of Aurka successfully halted disease progression. This model will be valuable for testing novel therapies and unraveling the mechanisms of eCCA tumorigenesis.

Combined Antitumor Effect of the Serine Protease Urokinase Inhibitor Upamostat and the Sphingosine Kinase 2 Inhibitor Opaganib on Cholangiocarcinoma Patient-Derived Xenografts.

Upamostat is an orally available small-molecule serine protease inhibitor that is a highly potent inhibitor of trypsin 1, trypsin 2, trypsin 3 (PRSS1/2/3), and the urokinase-type plasminogen activator (uPA). These enzymes are expressed in many cancers, especially during tissue remodeling and subsequent tumor cell invasion. Opaganib (ABC294640), a novel, orally available small molecule is a selective inhibitor of the phosphorylation of sphingosine to sphingosine-1-phosphate (S-1-P) by sphingosine kinase 2 (SPHK2). Both sphingosine kinase 1 (SPHK1) and SPHK2 are known to regulate the proliferation-inducing compound S-1-P. However, SPHK2 is more critical in cancer pathogenesis. The goal of this project was to investigate the potential antitumor effects of upamostat and opaganib, individually and in combination, on cholangiocarcinoma (CCA) xenografts in nude mice. PAX165, a patient-derived xenograft (PDX) from a surgically resected CCA, expresses substantial levels of SPHK2, PRSS1, PRSS2, and PRSS3. Four groups of 18 mice each were treated with upamostat, opaganib, both, or vehicle. Mouse weights and PAX165 tumor volumes were measured. Tumor volumes in the upamostat, opaganib, and upamostat plus opaganib groups were significantly decreased compared to the control group.

Tumor mutational load is prognostic for progression to therapy among high-count monoclonal B-cell lymphocytosis.

ABSTRACT: High-count monoclonal B-cell lymphocytosis (HCMBL) is a precursor condition to chronic lymphocytic leukemia (CLL). We have shown that among individuals with HCMBL, the CLL-International Prognostic Index (CLL-IPI) is prognostic for time-to-first therapy (TTFT). Little is known about the prognostic impact of somatically mutated genes among individuals with HCMBL. We sequenced DNA from 371 individuals with HCMBL using a targeted sequencing panel of 59 recurrently mutated genes in CLL to identify high-impact mutations. We compared the sequencing results with that of our treatment-naïve CLL cohort (N = 855) and used Cox regression to estimate hazard ratios and 95% confidence intervals (CIs) for associations with TTFT. The frequencies of any mutated genes were lower in HCMBL (52%) than CLL (70%). At 10 years, 37% of individuals with HCMBL with any mutated gene had progressed requiring treatment compared with 10% among individuals with HCMBL with no mutations; this led to 5.4-fold shorter TTFT (95% CI, 2.6-11.0) among HCMBL with any mutated gene vs none, independent of CLL-IPI. When considering individuals with low risk of progression according to CLL-IPI, those with HCMBL with any mutations had 4.3-fold shorter TTFT (95% CI, 1.6-11.8) vs those with none. Finally, when considering both CLL-IPI and any mutated gene status, we observed individuals with HCMBL who were high risk for both prognostic factors had worse prognosis than patients with low-risk CLL (ie, 5-year progression rate of 32% vs 21%, respectively). Among HCMBL, the frequency of somatically mutated genes at diagnosis is lower than that of CLL. Accounting for both the number of mutated genes and CLL-IPI can identify individuals with HCMBL with more aggressive clinical course.

Patient Perceptions of Same-Day Discharge Versus Overnight Stay After Total Joint Arthroplasty: Results of a Survey.

Background: In the COVID-19 era, there has been increasing interest in same-day discharge (SDD) after total joint arthroplasty (TJA). However, patient perception of SDD is not well reported. Purpose: We sought to understand patients' perceptions and preferences of postoperative care by surveying patients who have completed both an overnight stay (ONS) and an SDD after TJA. Methods: We emailed survey links to 67 patients who previously underwent either 2 total hip arthroplasties (THAs) or 2 total knee arthroplasties (TKAs). Results: Fifty-two patients (78%) responded to the survey. Thirty-four (65%) patients underwent staged, bilateral TKAs, and 18 (35%) patients underwent staged, bilateral THAs. Overall, 63% of patients preferred their SDD, 12% had no preference, and 25% preferred their ONS, with no difference in preference between TKA and THA groups. Those who preferred their SDD reported being more comfortable at home. Those who preferred their ONS felt their pain and concerns were better addressed. No differences were found in comfort, sleep quality, appetite, burden on family, return to function, feelings of being discharged too soon, overall experience, 30-day emergency department (ED) visits, or readmissions within 30 days between patients' SDD and ONS. There was a small statistically significant difference between patients' perception of safety between SDD and ONS. Conclusion: Our survey found that most patients reported a preference for SDD after TJA over ONS. Although there was a small difference in patient perception of safety, there were no differences in return to the ED or readmissions after SDD and ONS.

A lesion in two: Buruli ulcer and squamous cell carcinoma coexistence.

The concurrent diagnoses of Buruli ulcer (BU) and cutaneous squamous cell carcinoma (SCC) is a phenomenon not previously described, despite the fact that both conditions are highly prevalent in Australia. This report presents an intriguing case of concurrent diagnoses, with clues alluding to more than one skin condition being present. The case involves a 73-year-old man with BU diagnosed on the scalp, an atypical location, which led to the consideration of malignancy, ultimately revealing concurrent SCC. This case highlights the importance of considering both conditions in patients with epidemiological risk factors, necessitating multiple lines of investigation for accurate diagnosis. Medical practitioners must remain vigilant and incorporate this possibility into their diagnostic algorithms for suspicious skin lesions to optimize treatment and outcomes. This is the first recorded instance of simultaneous diagnosis, underlining the need for enhanced awareness and attention to these unique cases.

Use of Ultrasound-Assisted, Catheter-Directed Thrombolysis in a Patient With High-Risk Pulmonary Embolism.

High-risk pulmonary embolism (PE) is a complex clinical entity associated with high mortality rates. Ultrasound-assisted, catheter-directed thrombolysis, typically used for intermediate-risk PE, may be a viable treatment approach for high-risk PE, particularly in patients at increased risk for major bleeding. This report describes a case in which ultrasound-assisted, catheter-directed thrombolysis was successfully used to treat high-risk PE in a female patient with extensive peritoneal metastases from gastric adenocarcinoma. Other examples from the literature, in which ultrasound-assisted, catheter-directed thrombolysis was used to treat high-risk PE, are also provided.

The Phenomenology of the Face-to-Facetime: A Levinasian Critique of the Virtual Clinic.

In order to promote social distancing during the recent COVID-19 pandemic, physicians and healthcare systems have made efforts to replace in-person with virtual clinic visits when feasible. While these efforts have been well received and seem compatible with sound clinical practice, they do not perfectly replicate the experience of a face-to-face exchange between doctor and patient. This essay attempts to describe features of the virtual visit that distinguish it from its face-to-face analog and considers the phenomenological work of Emmanuel Levinas in arguing that these differences may limit the force of the ethical summons a provider would otherwise experience before the face of a patient. The diminishment of this signal therapeutic experience may engender vocational as well as clinical consequences, which should be weighed against the practical benefits of the virtual visit as we consider whether our enthusiasm for this mode of practice should continue.

A Novel Evaluation Model for Assessing ChatGPT on Otolaryngology-Head and Neck Surgery Certification Examinations: Performance Study.

BACKGROUND: ChatGPT is among the most popular large language models (LLMs), exhibiting proficiency in various standardized tests, including multiple-choice medical board examinations. However, its performance on otolaryngology-head and neck surgery (OHNS) certification examinations and open-ended medical board certification examinations has not been reported. OBJECTIVE: We aimed to evaluate the performance of ChatGPT on OHNS board examinations and propose a novel method to assess an AI model's performance on open-ended medical board examination questions. METHODS: Twenty-one open-ended questions were adopted from the Royal College of Physicians and Surgeons of Canada's sample examination to query ChatGPT on April 11, 2023, with and without prompts. A new model, named Concordance, Validity, Safety, Competency (CVSC), was developed to evaluate its performance. RESULTS: In an open-ended question assessment, ChatGPT achieved a passing mark (an average of 75% across 3 trials) in the attempts and demonstrated higher accuracy with prompts. The model demonstrated high concordance (92.06%) and satisfactory validity. While demonstrating considerable consistency in regenerating answers, it often provided only partially correct responses. Notably, concerning features such as hallucinations and self-conflicting answers were observed. CONCLUSIONS: ChatGPT achieved a passing score in the sample examination and demonstrated the potential to pass the OHNS certification examination of the Royal College of Physicians and Surgeons of Canada. Some concerns remain due to its hallucinations, which could pose risks to patient safety. Further adjustments are necessary to yield safer and more accurate answers for clinical implementation.

Use of targeted SMS messaging to encourage COVID-19 oral antiviral uptake in South West Victoria.

OBJECTIVES: During winter 2022, as part of a multifaceted approach to optimise oral antiviral uptake in the Barwon South West region in Victoria, Australia, the Barwon South West Public Health Unit (BSWPHU) implemented an innovative, targeted SMS messaging program that encouraged people with coronavirus disease 2019 (COVID-19) to be assessed for antiviral treatment. In this study, we investigated patterns of antiviral uptake, identified barriers and facilitators to accessing antivirals, and examined the potential impact of targeted SMS messaging on oral antiviral uptake. METHODS: We conducted a cross-sectional study of notified COVID-19 cases aged 50 years and older, and Aboriginal and Torres Strait Islander people aged 30-49 years, in the BSWPHU catchment area over a 6-week period commencing 21 July 2022. We analysed survey data using descriptive statistics and generalised linear models. RESULTS: Of the 3829 survey respondents, 36.7% (95% confidence interval (CI) 35.2, 38.2) reported being prescribed oral antivirals, with 75.4% (95% CI 72.8, 77.9) of these aged ≥70. Antiviral prescriptions increased significantly over the 6-week survey period. Most prescriptions (87.5%; 95% CI 85.7, 89.2) were provided by the respondents' usual general practitioners (GPs). Barriers to receiving antivirals included respondents being unable to get a medical appointment in time (3.7%; 95% CI 3.1, 4.2), testing too late in their illness (2.3%; 95% CI 1.8, 2.8) and being unable to access medications in time after receiving a prescription (0.2%; 95% CI 0.1, 0.6). Facilitators to receiving antivirals included respondents first hearing about antivirals from a trusted source such as a family member, friend or usual doctor. Nearly one in eight people who were prescribed antivirals reported first hearing about them from the SMS message sent by BSWPHU. CONCLUSIONS: Oral antiviral treatment uptake in south-west Victoria in July-August 2022 was high among survey respondents and increased over time. GPs were the key prescribers in the community. Targeted SMS messaging to COVID-19 cases is a simple, low-cost intervention that potentially increases antiviral uptake.

Factors Affecting Medical Residents' Decisions to Work After Call.

BACKGROUND: Accreditation Council for Graduate Medical Education (ACGME) work-hour restrictions (WHRs) are intended to improve patient safety by reducing resident fatigue. Compliance with ACGME WHRs is not universal. PURPOSE: The purpose of this study was to identify factors that influence residents' decisions to take a postcall day (PCD) off according to ACGME WHRs. METHODS: Residents (N = 433) at one university were emailed a link to a survey in 2019. The survey included demographic details and a Discrete Choice Experiment examining influences on resident decisions to take a PCD off. RESULTS: One hundred seventy-five residents (40.4%) responded to the survey; 113 residents (26%) completed the survey. Positive feedback from attending physicians about taking PCDs off in the past had the greatest impact on respondents' decisions to take a PCD off, increasing the probability by 27.3%, followed by chief resident comments about the resident looking tired (16.6% increase), and having never heard their attendings comment about PCDs off as either positive or negative (13.9% increase). Factors that had the largest effect on decreasing the probability of taking a PCD were negative feedback about taking PCDs off (14.3% decrease), continuity of care concerns (10.8% decrease), and whether the resident was looking forward to an assignment (7.9% decrease). CONCLUSIONS: The most important influencer of residents' decisions to take a PCD off was related to feedback from their attending physicians, suggesting that compliance with WHRs can be improved by focusing on the residency program's safety culture.

Effectiveness of community-based oral antiviral treatments against severe COVID-19 outcomes in people 70 years and over in Victoria, Australia, 2022: an observational study.

Background: Oral Antiviral (OAV) COVID-19 treatments are widely used, but evidence for their effectiveness against the Omicron variant in higher risk, vaccinated individuals is limited. Methods: Retrospective study of two vaccinated cohorts of COVID-19 cases aged ≥70 years diagnosed during a BA.4/5 Omicron wave in Victoria, Australia. Cases received either nirmatrelvir-ritonavir or molnupiravir as their only treatment. Data linkage and logistic regression modelling was used to evaluate the association between treatment and death and hospitalisation and compared with no treatment. Findings: Of 38,933 individuals in the mortality study population, 13.5% (n = 5250) received nirmatrelvir-ritonavir, 51.3% (n = 19,962) received molnupiravir and 35.2% (n = 13,721) were untreated. Treatment was associated with a 57% (OR = 0.43, 95% CI 0.36-0.51) reduction in the odds of death, 73% (OR = 0.27, 95% CI 0.17-0.40) for nirmatrelvir-ritonavir and 55% (OR = 0.45, 95% CI 0.38-0.54) for molnupiravir. Treatment was associated with a 31% (OR = 0.69, 95% CI 0.55-0.86) reduction in the odds of hospitalisation, 40% (OR = 0.60, 95% CI 0.43-0.83) for nirmatrelvir-ritonavir and 29% (OR = 0.71, 95% CI 0.58-0.87) for molnupiravir. Cases treated within 1 day of diagnosis had a 61% reduction in the odds of death (OR = 0.39, 95% CI 0.33-0.46) compared with 33% reduction for a delay of 4 or more days (OR = 0.67, 95% CI 0.44-0.97). Interpretation: Treatment with both nirmatrelvir-ritonavir or molnupiravir was associated with a reduction in death and hospitalisation in vaccinated ≥70 years individuals during the Omicron era. Timely, equitable treatment with OAVs is an important tool in the fight against COVID-19. Funding: There was no funding for this study.

Comprehensive Case-Control Study of Protective and Risk Factors for Buruli Ulcer, Southeastern Australia.

To examine protective and risk factors for Buruli ulcer (BU), we conducted a case-control study of 245 adult BU cases and 481 postcode-matched controls across BU-endemic areas of Victoria, Australia. We calculated age- and sex-adjusted odds ratios for socio-environmental, host, and behavioral factors associated with BU by using conditional logistic regression. Odds of BU were >2-fold for persons with diabetes mellitus and persons working outdoors who had soil contact in BU-endemic areas (compared with indoor work) but were lower among persons who had bacillus Calmette-Guérin vaccinations. BU was associated with increasing numbers of possums and with ponds and bore water use at residences. Using insect repellent, covering arms and legs outdoors, and immediately washing wounds were protective; undertaking multiple protective behaviors was associated with the lowest odds of BU. Skin hygiene/protection behaviors and previous bacillus Calmette-Guérin vaccination might provide protection against BU in BU-endemic areas.

The devil you know and the devil you don't: current status and challenges of bovine tuberculosis eradication in the United States.

Having entered into its second century, the eradication program for bovine tuberculosis (bTB, caused by Mycobacterium bovis) in the United States of America occupies a position both enviable and daunting. Excepting four counties in Michigan comprising only 6109 km2 (0.06% of US land area) classified as Modified Accredited, as of April 2022 the entire country was considered Accredited Free of bTB by the US Department of Agriculture for cattle and bison. On the surface, the now well-described circumstances of endemic bTB in Michigan, where white-tailed deer (Odocoileus virginianus) serve as a free-ranging wildlife maintenance host, may appear to be the principal remaining barrier to national eradication. However, the situation there is unique in the U.S., and far-removed from the broader issues of bTB control in the remainder of the country. In Michigan, extensive surveillance for bTB in deer over the last quarter century, and regulatory measures to maximize the harvest of publicly-owned wildlife, have been implemented and sustained. Prevalence of bTB in deer has remained at a low level, although not sufficiently low to eliminate cattle herd infections. Public attitudes towards bTB, cattle and deer, and their relative importance, have been more influential in the management of the disease than any limitations of biological science. However, profound changes in the demographics and social attitudes of Michigan's human population are underway, changes which are likely to force a critical reevaluation of the bTB control strategies thus far considered integral. In the rest of the U.S. where bTB is not self-sustaining in wildlife, changes in the scale of cattle production, coupled with both technical and non-technical issues have created their own substantial challenges. It is against this diverse backdrop that the evolution of whole genome sequencing of M. bovis has revolutionized understanding of the history and ecology of bTB in Michigan, resolved previously undiscernible epidemiological puzzles, provided insights into zoonotic transmission, and unified eradication efforts across species and agencies. We describe the current status of bTB eradication in the U.S., how circumstances and management have changed, what has been learned, and what remains more elusive than ever.