Resolution of Historically Discordant Ames Test Negative / Rodent Carcinogenicity Positive N-nitrosamines using a Sensitive, OECD-aligned Design.

The in vitro Bacterial Reverse Mutation (Ames) Test is crucial for evaluating the mutagenicity of pharmaceutical impurities. For N-nitrosamines (NAs) historical data indicated that for certain members of this chemical class the outcomes of the Ames Test did not correlate with their associated rodent carcinogenicity outcomes. This has resulted in negative outcomes in an OECD aligned Ames Test alone (standard or enhanced) no longer being considered sufficient by regulatory authorities to assess potential carcinogenic risk of NAs if present as impurities in drug products. Consequently, extensive follow-up in vivo testing can be required to characterise the potential mutagenicity and genotoxic carcinogenicity of NA impurities (i.e., beyond that defined in the ICH M7 guideline for non-NA impurities). We previously demonstrated that the mutagenicity of alkyl-nitrosamines can be detected by the appropriately designed, OECD aligned Ames Test and identified those conditions that contributed most to assay sensitivity. This OECD aligned Ames Test design was used to assess seven NAs, i.e. (methyl(neopentyl)nitrosamine, N-methyl-N-nitroso-2-propanamine, N-nitrosodiisopropylamine, bis(2-methoxyethyl)nitrosoamine, N-nitroso-N-methyl-4-fluoroaniline, dinitrosoethambutol, (R,R)- and mononitrosocaffeidine) that were reported to be negative in historical Ames Tests but positive in rodent carcinogenicity studies. All seven of the NAs were demonstrated to be mutagenic in the OECD aligned Ames test and therefore these compounds should no longer be considered as discordant (false negatives) with respect to the correlation of the Ames Test and rodent carcinogenicity. These results confirm the sensitivity of the OECD aligned Ames Test for the detection of NA mutagenicity and provides further support of its pivotal placement within the ICH M7 framework for the assessment of mutagenic impurities in pharmaceuticals to limit potential carcinogenic risk. In addition, we present data for 1-cyclopentyl-4-nitrosopiperazine, that indicates it could serve as a suitable positive control to provide further confidence in the sensitivity of the Ames Test for the NA chemical class.

CRISPR-Based Therapy for Hereditary Angioedema.

BACKGROUND: Hereditary angioedema is a rare genetic disease characterized by severe and unpredictable swelling attacks. NTLA-2002 is an in vivo gene-editing therapy that is based on clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9. NTLA-2002 targets the gene encoding kallikrein B1 (KLKB1). A single dose of NTLA-2002 may provide lifelong control of angioedema attacks. METHODS: In this phase 2 portion of a phase 1-2 trial, we randomly assigned adults with hereditary angioedema in a 2:2:1 ratio to receive NTLA-2002 in a single dose of 25 mg or 50 mg or placebo. The primary end point was the number of angioedema attacks per month (the monthly attack rate) from week 1 through week 16. Secondary end points included safety, pharmacokinetics, and pharmacodynamics (i.e., the change from baseline in total plasma kallikrein protein level); exploratory end points included patient-reported outcomes. RESULTS: Of the 27 patients who underwent randomization, 10 received 25 mg of NTLA-2002, 11 received 50 mg, and 6 received placebo. From week 1 through week 16, the estimated mean monthly attack rate was 0.70 (95% confidence interval [CI], 0.25 to 1.98) with 25 mg of NTLA-2002, 0.65 (95% CI, 0.24 to 1.76) with 50 mg, and 2.82 (95% CI, 0.80 to 9.89) with placebo; the difference in the estimated mean attack rate with NTLA-2002 as compared with placebo was -75% with 25 mg and -77% with 50 mg. Among patients who received NTLA-2002, 4 of the 10 patients who received 25 mg (40%) and 8 of the 11 who received 50 mg (73%) were attack-free with no additional treatment during the period from week 1 through week 16. The most common adverse events among patients who received NTLA-2002 were headache, fatigue, and nasopharyngitis. The mean percent change in total plasma kallikrein protein levels from baseline to week 16 was -55% with 25 mg and -86% with 50 mg; levels remained unchanged with placebo. CONCLUSIONS: NTLA-2002 administered in a single dose of 25 mg or 50 mg reduced angioedema attacks and led to robust and sustained reduction in total plasma kallikrein levels in patients with hereditary angioedema. These results support continued investigation in a larger phase 3 trial. (Funded by Intellia Therapeutics; ClinicalTrials.gov number, NCT05120830; EudraCT number, 2021-001693-33.).

Upscaling biodiversity monitoring: Metabarcoding estimates 31,846 insect species from Malaise traps across Germany.

Mitigating ongoing losses of insects and their key functions (e.g. pollination) requires tracking large-scale and long-term community changes. However, doing so has been hindered by the high diversity of insect species that requires prohibitively high investments of time, funding and taxonomic expertise when addressed with conventional tools. Here, we show that these concerns can be addressed through a comprehensive, scalable and cost-efficient DNA metabarcoding workflow. We use 1815 samples from 75 Malaise traps across Germany from 2019 and 2020 to demonstrate how metabarcoding can be incorporated into large-scale insect monitoring networks for less than 50 € per sample, including supplies, labour and maintenance. We validated the detected species using two publicly available databases (GBOL and GBIF) and the judgement of taxonomic experts. With an average of 1.4 M sequence reads per sample we uncovered 10,803 validated insect species, of which 83.9% were represented by a single Operational Taxonomic Unit (OTU). We estimated another 21,043 plausible species, which we argue either lack a reference barcode or are undescribed. The total of 31,846 species is similar to the number of insect species known for Germany (~35,500). Because Malaise traps capture only a subset of insects, our approach identified many species likely unknown from Germany or new to science. Our reproducible workflow (~80% OTU-similarity among years) provides a blueprint for large-scale biodiversity monitoring of insects and other biodiversity components in near real time.

Teaching Medical Students to Communicate Risks Like Military Intelligence Analysts.

Communication about health often involves descriptions of risk: the probability or likelihood of an unfavorable outcome. Communicating risk helps individuals make choices about their own health by building understanding of potential outcomes and providing context for the importance of procedures, health interventions, and lifestyle choices. However, medical education in the United States does not provide future physicians with adequate statistical literacy to communicate risk effectively and rarely encourages them to practice communicating risk in pre-clinical years. Risk communication in military intelligence, a field with formalized risk language and training, offers a unique perspective into potential improvements for medical risk communication. With backgrounds in the military, public health, communication, surgery, and medical education, the authors offer the following recommendations to improve risk communication for medical students. (1) Encourage the use of numerical absolute risk when communicating among health practitioners to avoid varied interpretations of what different risk descriptors ("uncommon," "likely," or "low") might mean; (2) build efficient, teachable skills in use of patient-facing risk communication tools like comparative probabilities and visual aids; and (3) practice estimating risk through role-play of risk communication between medical students and standardized patients. By improving risk communication in medical education, future doctors will be better equipped to build trust through open communication and improve the health of the patients and the communities for whom they care.

Future needs for continuing innovation in hemophilia: improving outcomes for individuals of all severities, including women and those in resource-constrained regions.

Over recent decades, management of people with hemophilia (PwH) has been greatly improved by scientific advances that have resulted in a rich and varied therapeutic landscape. Nevertheless, treatment limitations continue to drive innovation, and emerging options have the potential to realize further improvement. We advocate four general principles to optimize benefits from innovation: individualizing the treatment approach, targeting 'normal,' making the most of available resources, and considering treatment affordability. Ultimately, all PwH-men and women, of all ages and severities, and worldwide-should have access to treatment that fully prevents bleeding, while allowing personal, social, family, and professional lives of choice. Clearly, we are not there yet, but developing goals/milestones based on the principles we describe may help to achieve this.

Control of myopia using diffusion optics spectacle lenses: 4-year results of a multicentre randomised controlled, efficacy and safety study (CYPRESS).

AIMS: To evaluate the myopia control efficacy of Diffusion Optics Technology (DOT) spectacle lenses in children over a 4-year treatment period. METHODS: CYPRESS Part 1 (NCT03623074) was a 3-year multicentre, randomised, controlled, double-masked trial comparing two investigational spectacle lens DOT designs (Test 1, Test 2) and standard single vision Control lenses in 256 North American children aged 6-10 years. Children completing Part 1 (n=200) were invited to enrol in CYPRESS Part 2 (NCT04947735) for an additional 1-year period. In Part 2, Test 1 (n=35) and Control groups (n=42) continued with their original lens assignment and the Test 2 group (n=21) were crossed over to Test 1 (DOT 0.2) lenses. The co-primary endpoints were change from baseline in axial length (AL) and cycloplegic spherical equivalent refraction (cSER). RESULTS: Test 1 spectacle lenses demonstrated superiority to the Control in both co-primary endpoints: with a difference between means (Test 1-Control) of -0.13 mm for AL (p=0.018) and 0.33 D for cSER (p=0.008) in Part 1 and -0.05 mm for AL (p=0.038) and 0.13 D for cSER (p=0.043) in Part 2. Comparing treatment effects in Part 1 and 2 suggests that COVID-19 public health restrictions negatively impacted treatment efficacy in study years 2 and 3. CONCLUSION: DOT 0.2 spectacle lenses are safe and effective at reducing myopia progression, with additional benefit evident in year 4 of wear. These results support the hypothesis that a mild reduction in retinal contrast can slow myopia progression in young children. The unprecedented disruption in participant schooling and lifestyle during the COVID-19 pandemic may have depressed treatment efficacy in Part 1.

Stephen Hawking's Warning on Contacting Aliens: A Physics Perspective on the Intelligence Trap.

The search for extraterrestrial intelligence is a fascinating and important endeavor, but it raises significant ethical and safety concerns. In the search for extraterrestrial intelligence, scientists use knowledge of physics to identify potential communication methods and signals that may be used by extraterrestrial civilizations. One of the most notable scientists to highlight these concerns was the late physicist Stephen Hawking, who cautioned that actively attempting to communicate with extraterrestrial civilizations could harm humanity. While it is true that we cannot predict the intentions of any potential extraterrestrial civilizations, some scientists argue that the potential advantages of seeking contact outweigh the potential risks. Deciding to initiate contact with extraterrestrial civilizations is a complex issue that requires balancing scientific curiosity with concerns for our own safety. The "Intelligence Trap" is a concept in psychology that suggests that highly intelligent people are more susceptible to cognitive biases and flawed thinking than less intelligent people. It can be argued that Hawking's warnings may be an example of the so-called intelligence trap, as some evidence from the field of physics suggests. Nonetheless, Hawking emphasized that it is crucial for scientists and policymakers to carefully weigh the potential risks and benefits of such efforts and proceed with caution.

Accuracy of Non-Invasive Imaging Techniques for the Diagnosis of MASH in Patients With MASLD: A Systematic Review.

BACKGROUND AND AIMS: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing public health problem. The secondary stage in MASLD is steatohepatitis (MASH), the co-existence of steatosis and inflammation, a leading cause of progression to fibrosis and mortality. MASH resolution alone improves survival. Currently, MASH diagnosis is via liver biopsy. This study sought to evaluate the accuracy of imaging-based tests for MASH diagnosis, which offer a non-invasive method of diagnosis. METHODS: Eight academic literature databases were searched and references of previous systematic reviews and included papers were checked for additional papers. Liver biopsy was used for reference standard. RESULTS: We report on 69 imaging-based studies. There were 31 studies on MRI, 27 on ultrasound, five on CT, 13 on transient elastography, eight on controlled attenuation parameter (CAP) and two on scintigraphy. The pathological definition of MASH was inconsistent, making it difficult to compare studies. 55/69 studies (79.71%) were deemed high-risk of bias as they had no preset thresholds and no validation. The two largest groups of imaging papers were on MRI and ultrasound. AUROCs were up to 0.93 for MRE, 0.90 for MRI, 1.0 for magnetic resonance spectroscopy (MRS) and 0.94 for ultrasound-based studies. CONCLUSIONS: Our study found that the most promising imaging tools are MRI techniques or ultrasound-based scores and confirmed there is potential to utilise these for MASH diagnosis. However, many publications are single studies without independent prospective validation. Without this, there is no clear imaging tool or score currently available that is reliably tested to diagnose MASH.

Gábor Transform-Based Antibody Quantitation in Serum: An Interlaboratory Liquid Chromatography/High-Resolution Mass Spectrometry Investigation.

Therapeutic monoclonal antibodies (t-mAbs) are crucial for treating various conditions, including cancers and autoimmune disorders. Accurate quantitation and pharmacokinetic monitoring of t-mAbs in serum are essential, but current methods like ligand binding assays (LBAs) and bottom-up peptide liquid chromatography-tandem mass spectrometry (LC-MS/MS) can lack the sensitivity and specificity needed to meet clinical demands. Emerging techniques using high-resolution mass spectrometry (HRMS) in top-down and middle-up approaches offer improved ability to accurately quantify mAb proteoforms apart from degradation products by keeping the sample proteins intact or minimizing digestion. This study describes the first use of Gábor transform (GT)-based iFAMS Quant+ software to quantify a t-mAb (vedolizumab) from ∼400 samples using an Agilent 6545XT AdvanceBio Q-TOF at the University of Oregon. These results are compared to a previously validated laboratory-developed test (LDT) from Mayo Clinic utilizing a Thermo Q Exactive Plus Orbitrap. The Mayo method used conventional extracted ion chromatograms (XICs) of select charge states for quantitation, while the iFAMS Quant+ method utilized GT-based charge state deconvolution, background subtraction, and signal integration. Calibration and quality control (QC) analyses and Passing-Bablok regression of 351 subject samples demonstrated excellent agreement between the two methods. The iFAMS Quant+ workflow exhibited unique advantages for characterizing interferents and analyte signal anomalies due to its deconvolution-based approach.

Initial feasibility evaluation of the RISES system: An innovative and activity-based closed-loop framework for spinal cord injury rehabilitation and recovery.

Background: Electrical stimulation of the spinal cord may improve rewiring of the affected pathways. Immediate modulation of stimulation parameters, and its effects of it on kinematics and electromyographic variables is unclear. Methods: This study piloted the safety and feasibility of the Reynolds Innovative Spinal Electrical Stimulation (RISES) technology with a focus on its novel closed-loop setting. This personalized, task-specific non-invasive stimulation system enables real-time stimulation parameter modulation and supports multi-data acquisition and storage. Four SCI participants underwent a clinical trial coupled with activity-based training. Primary safety outcome measures included adverse events (AEs) and skin integrity; secondary measures were vital signs, pain, and fatigue assessed at the pre, mid, and post-stimulation sessions. The trial included open-loop and closed-loop blocks of transcutaneous spinal cord stimulation (tSCS). Results: Results showed no serious adverse events, with skin integrity unaffected. Vital signs and pain showed no significant differences across session timepoints. Fatigue levels differed significantly with post-session > mid-session > pre-session. Comparisons between open-loop and closed-loop blocks showed no significant differences in setup time, vital signs, pain, or fatigue. Average stimulation duration per task was significantly longer for open-loop (467.6 sec) than Closed-loop (410.8 sec). Conclusions: RISES, demonstrated safety and feasibility. Further work will focus on clinical efficacy.

An ILC2-chitinase circuit restores lung homeostasis after epithelial injury.

Environmental exposures increase the risk for severe lung disease, but specific drivers of persistent epithelial injury and immune dysfunction remain unclear. Here, we identify a feedback circuit triggered by chitin, a common component of airborne particles, that affects lung health after epithelial injury. In mice, epithelial damage disrupts lung chitinase activity, leading to environmental chitin accumulation, impaired epithelial renewal, and group 2 innate lymphoid cell (ILC2) activation. ILC2s, in turn, restore homeostasis by inducing acidic mammalian chitinase (AMCase) in regenerating epithelial cells and promoting chitin degradation, epithelial differentiation, and inflammatory resolution. Mice lacking AMCase or ILC2s fail to clear chitin and exhibit increased mortality and impaired epithelial regeneration after injury. These effects are ameliorated by chitinase replacement therapy, demonstrating that chitin degradation is crucial for recovery after various forms of lung perturbation. Thus, the ILC2-chitinase response circuit may serve as a target for alleviating persistent postinjury lung epithelial and immune dysfunction.

Promise and Peril of a Genotype-First Approach to Mendelian Cardiovascular Disease.

Precision medicine, which among other aspects includes an individual's genomic data in diagnosis and management, has become the standard-of-care for Mendelian cardiovascular disease (CVD). However, early identification and management of asymptomatic patients with potentially lethal and manageable Mendelian CVD through screening, which is the promise of precision health, remains an unsolved challenge. The reduced costs of genomic sequencing have enabled the creation of biobanks containing in-depth genetic and health information, which have facilitated the understanding of genetic variation, penetrance, and expressivity, moving us closer to the genotype-first screening of asymptomatic individuals for Mendelian CVD. This approach could transform health care by diagnostic refinement and facilitating prevention or therapeutic interventions. Yet, potential benefits must be weighed against the potential risks, which include evolving variant pathogenicity assertion or identification of variants with low disease penetrance; costly, stressful, and inappropriate diagnostic evaluations; negative psychological impact; disqualification for employment or of competitive sports; and denial of insurance. Furthermore, the natural history of Mendelian CVD is often unpredictable, making identification of those who will benefit from preventive measures a priority. Currently, there is insufficient evidence that population-based genetic screening for Mendelian CVD can reduce adverse outcomes at a reasonable cost to an extent that outweighs the harms of true-positive and false-positive results. Besides technical, clinical, and financial burdens, ethical and legal aspects pose unprecedented challenges. This review highlights key developments in the field of genotype-first approaches to Mendelian CVD and summarizes challenges with potential solutions that can pave the way for implementing this approach for clinical care.

The contact lens-tear film interface: Investigating the tear envelope.

PURPOSE: To explore the complex interface between the tear film, a unique mucosal fluid which is fundamental to ocular homeostasis and optimal vision, and an in-situ contact lens. This study exploits the use of a unique tear envelope (TE) extraction technique, which harvests the material-influenced layer of tear film that is in intimate contact with the lens during wear, to specifically investigate the influence of contact lens wear on tear film protein dynamics. METHODS: TEs were collected from freshly removed worn lens using a novel microcentrifuge 'piggyback' technique. Two distinct ex vivo studies were performed to investigate the key influencing factors involved. Non lens-wearing tear samples were also collected from all wearers. A compositional protein profile for each TE and tear film (TF) sample was obtained using an Agilent 2100 Bioanalyzer lab-on-a-chip microfluidic assay which detected proteins in a 14-230 kDa range. RESULTS: The data demonstrated that the TE protein compositional profile was quite distinct from either that of tear components deposited on the lens or those held in the tear menisci. For example, for one of the participant subgroups the tear protein average values in tears (n = 39) were determined at 35.2 ± 2.5 % lysozyme, 17.2 ± 0.6 % lipocalin, 7.3 ± 1.6 % IgA, 20.3 ± 1.3 % lactoferrin and 0.4 ± 0.4 % albumin as a function of total protein detected. In contrast, the average TE values were measured at 49.2 ± 3.7 %, 21.3 ± 3.9 %, 7.8 ± 1.6 % and 10.2 ± 1.7 % and 1.3 ± 2.8 % respectively with omafilcon A wear. In addition, 63 % of all TE samples (n = 180) (wearing lotrafilcon B and omafilcon A lenses) were albumin positive compared with only 19 % of all pre-lens insertion tear film samples (n = 237). CONCLUSIONS: The TE approach not only allows material differentiation, but it can determine changes in the ocular host response that may otherwise be missed by sole non lens-wearing tear film sample analysis.

Frequency and Determinants of Levothyroxine Therapy Initiation for Veterans with Subclinical Hypothyroidism.

Background/Objectives: There is evidence of overtreatment in patients with subclinical hypothyroidism (SCH). We aimed to identify the proportion of patients treated for SCH and the determinants of thyroid hormone therapy initiation. Methods: We included a random sample of adult Veterans diagnosed with SCH from 1 January 2016 to 31 December 2018 and conducted univariate and multivariable logistic regression to identify factors associated with levothyroxine initiation. Results: Out of 229 Veterans with SCH [90.0% male, 87.2% White, 99.1% non-Hispanic, median age (interquartile range; IQR) 68 (17) years], 27.5% were treated with levothyroxine. The treated group had a higher proportion of White patients (95.2% vs. 84.2%, p = 0.039), a higher thyrotropin level [median (IQR), 6.98 (2.06) mIU/L vs. 6.14 (1.10) mIU/L, p = 0.0002], a higher proportion of patients with thyrotropin level ≥ 10 mIU/L (11.1% vs. 3.0%, p = 0.021), a lower frequency of confirmatory thyroid testing before initiating levothyroxine (49.2% vs. 97.0%, p < 0.0001), and a similar frequency of thyroid autoimmunity testing (3.2% vs. 0.6%, p = 0.18) compared to the untreated group. In a multivariable logistic regression analysis, White race (OR = 4.50, 95% CI 1.19 to 17.08, p = 0.026) and index thyrotropin level [OR = 1.71, 95% CI 1.24 to 2.35, p = 0.001; for every SD increase (1.6 mIU/L)] were associated with higher odds of treatment. Conclusions: Three in 10 Veterans with SCH received levothyroxine, often based on a single abnormal thyroid test without autoimmunity assessment. White race and higher thyrotropin level were linked to increased odds of starting treatment, indicating potential disparities and the influence of SCH severity on decision-making.

Incidence, description, and timing of serious and opportunistic infections in patients with hairy cell leukemia.

Hairy cell leukemia is an uncommon B-cell malignancy with excellent response to purine analogs and to targeted therapies such as ibrutinib and vemurafenib. However, purine analogs are known to be highly immunosuppressive and the infection burden in this patient population with current therapies is unknown. We therefore conducted a retrospective cohort study following 149 patients. Median follow-up time was 6.9 years. Thirty-six percent developed an opportunistic or serious infection requiring hospitalization. Most cases were bacterial and most coincided with neutropenia and/or CD4 T-lymphopenia. No single treatment agent was significantly associated with increased or decreased incidence of infection. Reassuringly, the cumulative incidence of infections plateaued 2 months after initial treatment suggesting clinically significant immune recovery. Only one patient in our cohort passed away due to infection. Estimated 10-year overall survival was 99% suggesting that infections may not cause as much mortality as was seen prior to current therapies.

Quantifying cost-savings in the treatment of neovascular age-related macular degeneration in Aotearoa New Zealand.

AIMS: To estimate the cost-impact if faricimab were approved for the treatment of neovascular age-related macular degeneration (nAMD) in New Zealand. METHODS: A retrospective, single-centre cost-analysis study. Data on intravitreal agent and injection intervals were obtained and statistically compared. Cost estimates were based on internal facility and publicly available data. The current costs of care were compared to two scenarios: one where all eyes receive faricimab, and another where eyes receiving aflibercept switch to faricimab. RESULTS: A total of 352 eyes from 292 patients were analysed. Present values locally over 10 years were estimated at -$6,776,340 for the first scenario and $5,015,922 for the second, releasing 252 and 176 hours of clinical time per year, respectively. Nationally, the savings extrapolated to -$187,925,737 and $139,104,706, respectively. The analysis indicates significant direct cost savings for the health sector and potential reductions in patient harm due to fewer injections. CONCLUSIONS: The approval of faricimab for the treatment of nAMD could result in substantial direct cost savings for the health sector. Additional benefits include reducing patient harm and improving ophthalmic health inequalities for Maori and Pacific peoples. Further research in diverse patient populations across multiple centres is needed to estimate the magnitude of cost savings more accurately. This study highlights the potential of faricimab to alleviate the treatment burden and provide a more sustainable healthcare option for nAMD in New Zealand, especially in cases of recalcitrant nAMD, if used in a tailored and patient-specific manner alongside the existing armamentarium of treatments.

A human model of Buruli ulcer: Provisional protocol for a Mycobacterium ulcerans controlled human infection study.

Critical knowledge gaps have impeded progress towards reducing the global burden of disease due to Mycobacterium ulcerans, the cause of the neglected tropical disease Buruli ulcer (BU). Development of a controlled human infection model of BU has been proposed as an experimental platform to explore host-pathogen interactions and evaluate tools for prevention, diagnosis, and treatment. We have previously introduced the use case for a new human model and identified M. ulcerans JKD8049 as a suitable challenge strain. Here, we present a provisional protocol for an initial study, for transparent peer review during the earliest stages of protocol development. Following simultaneous scientific peer review and community/stakeholder consultation of this provisional protocol, we aim to present a refined protocol for institutional review board (IRB) evaluation.

This paper describes a provisional clinical protocol for the pilot human challenge model of Mycobacterium ulcerans infection, which causes the skin disease 'Buruli ulcer' (BU). BU is typically painless and begins as a small area of redness or swelling, and is curable with antibiotics. If the diagnosis is delayed, it can result in large ulceration and disability. Side effects from antibiotics are common but rarely severe; nevertheless, preventative strategies, such as vaccination, are urgently needed. The overarching project, known as 'MuCHIM', aims to establish a safe and acceptable controlled human challenge model (CHIM) of this disease in healthy volunteers in Melbourne, Australia. This pilot protocol primarily aims to establish that it is safe and acceptable to participants, and secondarily to confirm successful establishment of infection and the infection rate amongst participants. We also aim to test less invasive diagnostic tests, assess immune responses to infection, to understand changes in the human microbiome during the trial, and explore microbiological characteristics of M. ulcerans infection. If this pilot is successful, we hope to test vaccines and other therapeutics using this model, which could blunt or reduce the rising incidence of this disease in Australia, while further informing vaccine development research.