Responses of tadpoles to hybrid predator odours: strong maternal signatures and the potential risk/response mismatch.

Previous studies have established that when a prey animal knows the identity of a particular predator, it can use this knowledge to make an 'educated guess' about similar novel predators. Such generalization of predator recognition may be particularly beneficial when prey are exposed to introduced and invasive species of predators or hybrids. Here, we examined generalization of predator recognition for woodfrog tadpoles exposed to novel trout predators. Tadpoles conditioned to recognize tiger trout, a hybrid derived from brown trout and brook trout, showed generalization of recognition of several unknown trout odours. Interestingly, the tadpoles showed stronger responses to odours of brown trout than brook trout. In a second experiment, we found that tadpoles trained to recognize brown trout showed stronger responses to tiger trout than those tadpoles trained to recognize brook trout. Given that tiger trout always have a brown trout mother and a brook trout father, these results suggest a strong maternal signature in trout odours. Tadpoles that were trained to recognize both brown trout and brook trout showed stronger response to novel tiger trout than those trained to recognize only brown trout or only brook trout. This is consistent with a peak shift in recognition, whereby cues that are intermediate between two known cues evoke stronger responses than either known cue. Given that our woodfrog tadpoles have no evolutionary or individual experience with trout, they have no way of knowing whether or not brook trout, brown trout or tiger trout are more dangerous. The differential intensity of responses that we observed to hybrid trout cues and each of the parental species indicates that there is a likely mismatch between risk and anti-predator response intensity. Future work needs to address the critical role of prey naivety on responses to invasive and introduced hybrid predators.

Optimizing the Diagnosis and Management of Pediatric Inducible Laryngeal Obstruction.

BACKGROUND: Pediatric inducible laryngeal obstruction (ILO) is difficult to diagnose and treat. Patients often undergo multiple specialist referrals, and long-term outcomes are not well reported. OBJECTIVES: To investigate the patterns of presentation, workup, and management of children who were diagnosed with ILO at the Stollery Children's Hospital. METHODS: Retrospective review with a prospective cohort of pediatric patients diagnosed with ILO from 2015 to 2023. We collected the demographic data, diagnostic tests, specialist referrals, time to diagnosis, symptom burden, associated comorbidities and aggravating factors, management, and treatment outcomes. A subset of patients was followed prospectively to determine treatment outcomes. A basic descriptive analysis was performed, and factors associated with time to resolution were studied. RESULTS: Seventy-eight patients met the criteria for inclusion, with 22 completing prospective questionnaires. The average age was 14 years old, and 75% were female. The majority required multiple specialist referrals. The majority were associated with exercise. Thirty-two (41%) patients had a presumed diagnosis of asthma, despite only four pulmonary function tests being consistent with asthma. Abortive breathing exercises were the most commonly employed (95%) and most successful (61%) nonsurgical management technique. Surgery was highly successful in a small cohort of patients. Median time to symptom resolution was 12 months, with 36% reporting symptoms persistent beyond 3 years. CONCLUSIONS: Pediatric ILO often goes undiagnosed for prolonged periods. Exercise-related symptoms are the most common. Management strategies have varied levels of success and a large proportion of patients have prolonged symptoms despite treatment, as supported by other recent evidence. LEVEL OF EVIDENCE: 3 Laryngoscope, 2024.

Prevalence and Risk Factors for Swallowing Dysfunction in Patients With Laryngomalacia Treated Medically and Surgically.

Objective: To identify the prevalence, pattern, and nature of swallowing dysfunction (SwD) in a consecutive cohort of patients with laryngomalacia (LM), and to determine factors associated with a higher burden of SwD. Study Design: This was a retrospective review of consecutive patients diagnosed with LM by 2 pediatric otolaryngologists between 2013 and 2022 and a minimum of 3-month follow-up. Setting: Tertiary care pediatric otolaryngology referral center. Methods: Consecutive cohort of patients less than 3 years old with LM diagnosed on flexible laryngoscopy were reviewed. Patients with incomplete follow-up, lack of swallowing assessment, and genetic conditions or syndromes were excluded. All patients underwent at minimum a systematic clinical swallowing evaluation by a speech-language pathologist specialized in pediatric dysphagia. Patients with concerning clinical exams underwent instrumental swallow evaluation (Videofluoroscopic Swallow Study [VFSS] or Flexible Endoscopic Evaluation of Swallowing [FEES]). The prevalence of abnormalities of clinical swallowing evaluation, instrumental swallow evaluation data, and details of management were collected. Results: Two hundred and twelve patients met criteria and were included in the final analysis. One hundred and fifteen patients (54%) had an instrumental assessment (VFSS or FEES). Of the instrumental assessments performed, 96 (69%) were abnormal. Of the total patient cohort, 55 (26%) had laryngeal penetration and/or aspiration. One hundred and seventeen (55%) had clinical or instrumental indications for intervention, with 18 (8%) requiring tube feeding. Patients with severe LM and those treated surgically had a statistically significant higher rate of penetration and aspiration. Conclusion: Patients with LM have a high burden of dysphagia requiring medical intervention. The authors advocate for routine and systematic assessment of all patients with LM for swallowing dysfunction.

A novel sleep oximetry scoring tool for pediatric laryngomalacia.

OBJECTIVE: Despite being a more accessible and less resource intensive modality than polysomnography, the utility of sleep oximetry (SO) in pediatric laryngomalacia (LM) is not well understood or validated. We aimed to retrospectively evaluate the utility of overnight home based SO in children with LM by developing and internally validating the Modified Laryngomalacia Oximetry Score (MLOS) scoring system to triage severity and guide clinical decision making. METHODS: We evaluated pediatric patients with a diagnosis of LM at our tertiary referral centre. Data from initial and post-treatment SO including mean oxygen saturation (spO2) nadir and mean oxygen desaturation index (ODI) were aggregated. The MLOS ranging from I-VI (inconclusive to severe) was created by two otolaryngologists to incorporate bradycardia associated desaturation events during SO. Corresponding McGill Oximetry Score (MOS) was also determined. RESULTS: 172 patients were included in final analysis. The average age was 9.2 ± 14.3 months. 98 (57%) of patients were identified as Thompson severity score 1, and 87 (50.6%) of patients underwent supraglottoplasty. The surgical cohort had a significantly higher MLOS and MOS scores of 4 and 2 respectively, and higher mean ODI and spO2 nadir metrics. When evaluating post-supraglottoplasty SO tracings, all parameters improved significantly, including median MLOS score from 4 to 1. Only the mean ODI improved in the non-surgical cohort. Patients with Thompson severity score 2/3 had significantly higher MLOS. CONCLUSION: We present a simple scoring system based on overnight SO, the MLOS, to help triage severity of pediatric LM and guide decision-making. MLOS is associated with worse clinical severity and a need for surgery, and shows significant improvement after surgery.

Students' perceptions of learning environment and their leisure-time exercise in medical school: Does sport background matter?

INTRODUCTION: The effectiveness of medical school efforts in addressing suboptimal student wellbeing rests, in part, on how students perceive their learning environment. The study aim was to determine whether students' sport background was a contributing factor in students' perceptions of the medical program as supportive of their basic psychological needs for autonomy, competence, and relatedness. We also examined the relationship between sport background and students' leisure-time exercise in medical school. METHODS: Using an online questionnaire, quantitative data were collected from students enrolled in the 4­year medical program at a large Canadian university. Two hundred (n = 200) students had complete responses on the measures used in the study. Analysis of variance and correlational analysis were used to examine the relationships between students' sport background, their perceptions of the learning environment, and leisure-time exercise in medical school. RESULTS: Compared with students with no sport background, students with a team sport background perceived their need for relatedness to be satisfied to a greater degree in the medical program. Students who pursued sports at higher levels of involvement (competitively) perceived the medical program as more autonomy-supportive than students who pursued sports at lower levels of involvement (recreationally). Irrespective of their sport background, students' involvement in leisure-time exercise decreased over the years in the medical program. However, students with a sport background engaged in leisure-time exercise in medical school to a greater extent than students with no sport background. DISCUSSION: The findings indicate that sport background is associated with students' perceptions of the learning environment as supportive of their needs for autonomy and relatedness, but not for competence, and is linked to their leisure-time exercise in medical school. The observed relationships could help inform medical schools curricular initiatives in preventing student burnout right from the start of medical school.

Association Between Family Medicine Residents' Mindsets and In-Training Exam Scores.

INTRODUCTION: In medical practice, a mastery mindset is important for engaging in lifelong learning. The objective of this study was to examine the association between family medicine residents' scores on mindset measures and their performance on in-training examinations (ITE). METHODS: This was a secondary data analysis of a cohort of family medicine residents. Following ethics approval, residents' ITE scores from each of the 2 years of residency were linked with residents' responses to a mindsets survey that they had taken at the midpoint of residency training. Multiple regression analysis was used to investigate the relationship between residents' mindset scores and their ITE scores. Of 85 residents, 46 (54%) had complete data for the three data collection points. RESULTS: Residents' ITE scores in year 1 were most predictive of their ITE scores in year 2 (ß=0.72; P<.001). Mastery mindset scores were negatively associated with residents' performance on the ITE in year 2 (ß=-0.29; P=.004). CONCLUSION: While the observed negative relationship between residents' mastery mindset scores and their ITE performance may be disconcerting, it is not surprising. In clinical settings, residents are individually coached by preceptors and provided with specific, actionable feedback to support their learning. With respect to formative assessments, residents likely require explicit training on how to use their assessment results (ITE scores) to support their self-directed learning. This finding has practical implications for residency programs in using ITEs as formative assessments.

Turnover of hydrogen isotopes in lake sturgeon blood: implications for tracking movements of wild populations.

Naturally occurring deuterium ((2)H) in biota can be used to trace movement, migration and geographic origin of a range of organisms. However, to evaluate movements of animals using δ(2)H measurements of tissues, it is necessary to establish the turnover time of (2)H in the tissues and the extent of isotopic discrimination from different environmental (2)H sources to those tissues. We investigated the turnover of (2)H in lake sturgeon (Acipenser fulvescens) blood by manipulating both environmental water δ(2)H and diet δ(2)H over a four-month period. The half-life of deuterium in lake sturgeon blood was 37.9 days after an increase in the environmental water δ(2)H of +714 ‰. However, no clear turnover in blood (2)H occurred over the same period in a separate trial following a change of -63.8 ‰ or +94.2 ‰ in diet. These findings suggest that environmental water (2)H exchanges much faster with blood than diets and that blood δ(2)H values can be used to trace movements of sturgeon and other fish moving among isotopically distinct waters.