Alterations of pleiotropic neuropeptide-receptor gene couples in Cetacea.

BACKGROUND: Habitat transitions have considerable consequences in organism homeostasis, as they require the adjustment of several concurrent physiological compartments to maintain stability and adapt to a changing environment. Within the range of molecules with a crucial role in the regulation of different physiological processes, neuropeptides are key agents. Here, we examined the coding status of several neuropeptides and their receptors with pleiotropic activity in Cetacea. RESULTS: Analysis of 202 mammalian genomes, including 41 species of Cetacea, exposed an intricate mutational landscape compatible with gene sequence modification and loss. Specifically for Cetacea, in the 12 genes analysed we have determined patterns of loss ranging from species-specific disruptive mutations (e.g. neuropeptide FF-amide peptide precursor; NPFF) to complete erosion of the gene across the cetacean stem lineage (e.g. somatostatin receptor 4; SSTR4). CONCLUSIONS: Impairment of some of these neuromodulators may have contributed to the unique energetic metabolism, circadian rhythmicity and diving response displayed by this group of iconic mammals.

Isotope-based inferences of the trophic niche of short-finned pilot whales in the Webbnesia.

Knowledge of predator-prey interactions is key in ecological studies and understanding ecosystem function, yet this is still poorly explored in the deep-sea environment. Carbon (δ13C: 13C/12C) and nitrogen (δ15N: 15N/14N) stable isotope ratios of a deep-diving species, the short-finned pilot whale (Globicephala macrorhynchus), were used to explore knowledge gaps on its ecological niche and foraging habitats in the Webbnesia marine ecoregion (Tenerife Island, n = 27 animals vs. Madeira, n = 31; 500 km apart) where animals display distinct levels of site fidelity. Specifically, we tested whether intraspecific isotopic variation results from differences between geographic areas (due to possible foraging plasticity between regions), sexes, and/or years (2015-2020) using Generalized Linear Models. In general, significant differences (p < 0.05) were found in the stable isotope profiles of pilot whales between the two archipelagos, which were also reflected in their isotopic niche. The higher mean and wider range of δ15N values in Tenerife suggest that pilot whales consume prey of higher trophic levels and more diverse than Madeira. The higher mean and wider range of δ13C values in Madeira suggest that in that island, pilot whales rely on prey from more diverse habitats. There was significant variation between some years, but not between sexes. Finally, we discuss pilot whales' foraging strategies worldwide and infer the reliance on benthic or benthopelagic food sources in the Webbnesia.

Pseudoephedrine-induced Fixed Drug Eruption in a Scuba Diver With Recurrent Palmoplantar Exfoliation.

Objectives: This report presents a case of pseudoephedrine-induced nonpigmented bullous fixed drug eruption (NBFDE) manifesting as recurrent palmoplantar exfoliation in a scuba diver. It emphasizes the importance of considering drug allergies in the differential diagnosis when divers present with peeling hands and soles. Methods: A 38-year-old female scuba diver experiencing recurrent palmoplantar exfoliation underwent a clinical evaluation, patch testing, an interferon-gamma enzyme-linked immunospot (ELISpot) assay, and graded drug challenges with pseudoephedrine and phenylephrine. Results: Patch testing yielded negative results; however, the ELISpot assay indicated a strong immune response to pseudoephedrine. A graded challenge involving pseudoephedrine successfully reproduced the symptoms, confirming a diagnosis of pseudoephedrine-induced NBFDE. Subsequently, a challenge with phenylephrine elicited a milder reaction, suggesting it as a potential alternative medication for the patient. Conclusions: This case highlights NBFDE as a potential cause of skin peeling in scuba divers who are allergic to pseudoephedrine. It emphasizes the importance of considering drug allergies when diagnosing palmoplantar exfoliation in divers and underscores the need for a thorough evaluation of medication use in this group. Alternative medications and management strategies should be considered for divers with a pseudoephedrine allergy to prevent ear barotrauma while minimizing the risk of adverse skin reactions.

The independent effects of hydrostatic pressure and hypercapnic breathing during water immersion on ventilatory sensitivity and cerebrovascular reactivity.

Head out water immersion (HOWI) induces ventilatory and hemodynamic changes, which may be a result of hydrostatic pressure, augmented arterial CO2 tension, or a combination of both. We hypothesized that the hydrostatic pressure and elevated CO2 tension that occur during HOWI will contribute to an augmented ventilatory sensitivity to CO2 and an attenuated cerebrovascular reactivity to CO2 during water immersion. Twelve subjects (age: 24±3 y, BMI: 25±3 kg/m2) completed HOWI, waist water immersion with CO2 (WWI+CO2), and WWI where a rebreathing test was conducted at baseline, 10, 30, and 60 minutes, and post. PETCO2, minute ventilation, expired gases, blood pressure, heart rate, and middle cerebral artery blood velocity were recorded continuously. PETCO2 increased throughout all visits (p£0.011), was matched during HOWI and WWI+CO2 (p³0.264), and was greater during WWI+CO2 vs. WWI at 10, 30, and 60 minutes (p<0.001). When HOWI vs. WWI+CO2 were compared, the change in ventilatory sensitivity to CO2 was different at 10 (0.59±0.34 vs. 0.06±0.23 L/min/mmHg, p<0.001), 30 (0.58±0.46 vs. 0.15±0.25 L/min/mmHg, p<0.001), and 60 minutes (0.63±0.45 vs. 0.16±0.34 L/min/mmHg, p<0.001), while there were no differences between conditions for cerebrovascular reactivity to CO2 (p³0.163). When WWI+CO2 vs. WWI were compared, ventilatory sensitivity to CO2 was not different between conditions (p³0.642), while the change in cerebrovascular reactivity to CO2 was different at 30 minutes (-0.56±0.38 vs. -0.30±0.25 cm/s/mmHg, p=0.010). These data indicate that during HOWI ventilatory sensitivity to CO2 increases due to the hydrostatic pressure, while cerebrovascular reactivity to CO2 decreases due to the combined effects of immersion.

Recurrent decompression sickness and late repermeabilization of patent foramen oval closure prosthesis: a diver's dilemma-case report.

Background: Decompression sickness (DCS) is a well-known risk associated with scuba diving, particularly in people with right-to-left shunt, such as patent foramen oval (PFO). Herein, we present a unique case of late PFO permeabilization after closure. Case summary: A 26-year-old male diver was diagnosed with DCS following a dive at 36 m. He underwent PFO closure with a STARFLEX® prosthesis. Ten years later, the patient was presented with recurrent manifestations suggestive of DCS. The performed diagnostic work-up detects a permeabilization of the implanted prosthesis, and he was treated with a conservative approach. Discussion: This case highlights the challenges in the management of PFO in divers and raises concerns about the long-term efficiency of PFO closure and the impact of diving-related factors on prosthesis patency.

Creating Local "Citizen's Governance Spaces" in Austerity Contexts : Food Recuperation and Urban Gardening in Montréal (Canada) as Ways to Pragmatically Invent Alternatives.

While there is a growing interest in citizen-led initiatives, there is still no consensus on how to situate them, especially in relation to state institutions. On the one hand, citizen-led initiatives are seen as being co-opted by formal institutions in a context of austerity. On the other hand, these initiatives are often presented as "spaces of resistance" to neoliberalism, or as political acts of reclaiming the city. Mapping and tracing urban gardening and dumpster diving from their grassroots emergence to their inclusion in the institutional world through a two-level analysis, we show that individuals and loosely organized collectives involved in such initiatives are embedded in complex relationships with local institutions and third sector organizations that do, in turn, structure their practice and its consequences. The two-level analysis we propose follows this process: it is through interactions and relationships with other "practitioners" and with their social and institutional environment that these urban social practices gradually institutionalize.

Acute massive posterior stroke with tonsillar herniation in a scuba diver.

A transient female passenger in her 40s presented to the emergency department (ED) exhibiting drowsiness post-scuba diving. Despite normal initial vitals, she reported dizziness, sleepiness, and occipital headache. A computed tomography (CT) scan showed a severe posterior circulation acute infarction affecting various brain regions, resulting in significant mass effects and complications like 4th ventricle compression, cerebellar tonsillar herniation, and hydrocephalus. Extensive diagnostic tests, blood workup, and stroke evaluations revealed normal findings, except for an incidental patent foramen ovale (PFO). Collaboration with neurosurgery led to her transfer for life-saving extraventricular drain (EVD) insertion and posterior fossa decompression. Treatment included right-side EVD insertion, suboccipital craniectomy, and foramen magnum decompression. Postoperatively, she was extubated the next day, alert, without focal neurological deficits. Upon EVD removal, a repeat CT head scan showed regression of mass effect. She was discharged home safely after 16 days, fully ambulating.

The role of cognition as a factor regulating the diving responses of animals, including humans.

The dive response involves three main components - breath holding, reduced heart rate and increased peripheral vasoconstriction - and is ubiquitous during forced dives in air-breathing vertebrates; however, numerous studies in free-diving animals have shown that the heart rate response to diving varies considerably in a manner that suggests cognitive control. Furthermore, studies on free-diving animals and controlled experiments in trained animals both indicate that the dive response can be conditioned, such that the reduction in heart rate begins before submergence and the extent of the reduction is set early in the dive. In addition, numerous species also experience an increase in heart rate and blood flow during ascent at the end of a dive, a phenomenon commonly called 'ascent tachycardia'. Collectively, these data suggest that although the dive response is under autonomic control, many species can vary its magnitude depending on the length and type of the planned dive - an indication of a role for cognition in the overall physiological responses associated with diving. Here, we provide examples of the conditioned cardiac responses - including anticipatory changes in heart rate - in several diving species and propose potential underlying mechanisms. We also discuss how the anticipatory cardiovascular responses not only improve diving capacity, but also prevent diving-related problems, such as decompression sickness or barotrauma, through a mechanism described by the selective gas exchange hypothesis.

Acute Effects of Breath-Hold Conditions on Aerobic Fitness in Elite Rugby Players.

The effects of face immersion and concurrent exercise on the diving reflex evoked by breath-hold (BH) differ, yet little is known about the combined effects of different BH conditions on aerobic fitness in elite athletes. This study aimed to assess the acute effects of various BH conditions on 18 male elite rugby players (age: 23.5 ± 1.8 years; height: 183.3 ± 3.4 cm; body mass: 84.8 ± 8.5 kg) and identify the BH condition eliciting the greatest aerobic fitness activation. Participants underwent five warm-up conditions: baseline regular breathing, dynamic dry BH (DD), static dry BH (SD), wet dynamic BH (WD), and wet static BH (WS). Significant differences (p < 0.05) were found in red blood cells (RBCs), red blood cell volume (RGB), and hematocrit (HCT) pre- and post-warm-up. Peak oxygen uptake (VO2peak) and relative oxygen uptake (VO2/kgpeak) varied significantly across conditions, with BH groups showing notably higher values than the regular breathing group (p < 0.05). Interaction effects of facial immersion and movement conditions were significant for VO2peak, VO2/kgpeak, and the cardiopulmonary optimal point (p < 0.05). Specifically, VO2peak and peak stroke volume (SVpeak) were significantly higher in the DD group compared to that in other conditions. Increases in VO2peak were strongly correlated with changes in RBCs and HCT induced by DD warm-up (r∆RBC = 0.84, r∆HCT = 0.77, p < 0.01). In conclusion, DD BH warm-up appears to optimize subsequent aerobic performance in elite athletes.

Development of an algorithm to guide management of cardiorespiratory arrest in a diving bell.

Aim: The management of cardiorespiratory arrest in a diving bell presents multiple clinical, technical, and environmental considerations that standard resuscitation algorithms do not address, and no situation-specific algorithm exists. The development and testing of an algorithm to guide the management of cardiorespiratory arrest in a bell is described. Methods: An iterative approach to algorithm development was used. Phase 1 involved a small multidisciplinary group and took place in a simulation centre and a decommissioned diving bell. The algorithm was then refined in a purpose-build simulation complex with repeated simulation by a group of divers, and with input from industry experts. ALS principles were followed unless contextual or technical factors necessitated deviation. Results: Clinical and technical aspects of the resuscitation are addressed. Key priorities that conflict with standard ALS principles are: prioritisation of rescue breaths; use of mechanical CPR when available; and the provision of CPR with the casualty in a seated position where necessary. Conclusion: This is the first algorithm to guide the delivery of resuscitation in a diving bell. It incorporates adapted ALS principles and available data concerning compression technique effectiveness, and was informed by industry and clinical expertise. It provides guiding principles that can be adapted to setting-specific needs, and we would encourage its industry-wide international adoption.

CARDIOVASCULAR AND HEMATOLOGICAL RESPONSES TO A DRY DYNAMIC APNEA IN BREATH HOLD DIVERS.

The mammalian dive reflex, characterized by bradycardia and peripheral vasoconstriction, occurs in all mammals, including humans, in response to apnea. However, the dive reflex to a single, maximal, dry, dynamic apnea (DYN), and how it compares to a time-matched exercise control trial (EX) or dry static apnea (SA), has not been studied. We examined the hypotheses that, compared to EX and SA, the magnitude of the (a) cardiovascular response and (b) hematological response to DYN would be greater. Cardiovascular parameters (heart rate [HR], systolic [SBP], diastolic [DBP], and mean arterial [MAP] blood pressure) were continuously collected in twenty-three (F=6) moderate and elite freedivers, first during a maximal DYN, then during a time-matched SA and EX on a swimming ergometer in randomized order. Venous blood draws were made prior to and following each trial. The change in calculated oxygen saturation (DYN:-17±13%, EX:-2±1%, ΔSA:-2±1%;P<0.05, all comparisons) was greater during DYN compared to EX and SA. During DYN, ΔSBP (DYN:104±31mmHg, EX:38±23mmHg, SA:20±11mmHg), ΔDBP (DYN:45±12mmHg, EX:14±10mmHg, SA:15±8mmHg) and ΔMAP (DYN:65±17mmHg EX:22±13mmHg, SA:16±9mmHg) were increased compared to EX and SA, while ΔHR was greater during EX (DYN:-24±23bpm, EX:33±13bpm, SA:-1±10bpm) than either DYN or SA (P<0.0001, all comparisons). Females had greater pressor response to EX (ΔSBP:59±30mmHg, ΔDBP:24±14mmHg, ΔMAP:35±8mmHg) than males (ΔSBP:31±15mmHg, ΔDBP:11±6mmHg, ΔMAP:18±8mmHg; P<0.01, all comparisons). Together, these data indicate that DYN elicits a distinct, exaggerated cardiovascular response compared to EX or SA alone.

Bubble blasts! An adaptation for buoyancy regulation in shallow foraging gray whales.

Foraging efficiency is key to animal fitness. Consequently, animals evolved a variety of kinematic, morphological, physiological, and behavioral adaptations for efficient locomotion to reduce energy expenditure while moving to find, capture, and consume prey. Often suited to specific habitat and prey types, these adaptations correspond to the terrain or substrate the animal moves through. In aquatic systems, adaptations focus on overcoming drag, buoyancy, and hydrostatic forces. Buoyancy both benefits and hinders diving animals; in particular, shallow divers constantly contend with the costs of overcoming buoyancy to dive and maintain position. Pacific Coast Feeding Group (PCFG) gray whales forage in shallow habitats where they work against buoyancy to dive and feed using various foraging tactics. Bubble blasts (underwater exhalations) have been observed during several foraging tactics performed by PCFG whales. As exhalations aid buoyancy regulation in other diving animals, we hypothesize that bubble blasts are performed by longer, more buoyant whales in shallower water and that bubble blasts increase dive duration while accounting for size and tactic. We test our hypotheses using Bayesian linear mixed effects models and a 7-year dataset of drone footage containing concurrent individual morphological and behavioral data. We find that while headstanding - a stationary, head-down tactic - bubble blasts are performed by longer, more buoyant whales and extend the dive duration, whereas whales using forward-swimming tactics are less likely to bubble blast. Our results suggest that PCFG gray whales may use bubble blasts as a behavioral adaption to mitigate the cost of energetically expensive tactics in their shallow habitat foraging niche.

Context-driven communication during deep-sea foraging in a social toothed whale.

Social deep-diving odontocetes face the challenge of balancing near-surface proximity to oxygen and group members with foraging in the deep sea. Individuals rely on conspecifics for critical life functions, such as predator defence, but disperse during foraging to feed individually. To understand the role of social acoustic mediation during foraging in deep-diving toothed whales, we investigated the context of social burst-pulse call production in Risso's dolphin (Grampus griseus) using biologgers. Dolphins produced context-specific burst pulses predominantly during daytime foraging, preceding or following foraging dives and in the early descent of daytime deep dives. Individuals applied differential short and long burst-pulse calls intended for either near-surface receivers (horizontal transmission) or deep-foraging receivers (vertical transmission). Our results show that deep-diving toothed whales are reliant on acoustic communication during certain foraging contexts, to relay information including foraging conditions or an individual's location. Moreover, they accentuate the importance of maintaining acoustic contact with conspecifics, specifically when dispersed during deeper foraging. It also signifies that our oceanic top predators may be specifically vulnerable to the current strong increase in anthropogenic noise. Potential masking of the signals from group members communicating at a distance could undermine their social cohesion, and hence their capacity to maintain vital life functions.

The bottlenose dolphin (Tursiops truncatus): a novel model for studying healthy arterial aging.

Endothelial function declines with aging and independently predicts future cardiovascular disease (CVD) events. Diving also impairs endothelial function in humans. Yet, dolphins, being long-lived mammals adapted to diving, undergo repetitive cycles of tissue hypoxia-reoxygenation and disturbed shear stress without manifesting any apparent detrimental effects, as CVD is essentially nonexistent in these animals. Thus, dolphins may be a unique model of healthy arterial aging and may provide insights into strategies for clinical medicine. Emerging evidence shows that the circulating milieu (bioactive factors in the blood) is at least partially responsible for transducing reductions in age-related endothelial function. To assess whether dolphins have preserved endothelial function with aging because of a protected circulating milieu, we tested if the serum (pool of the circulating milieu) of bottlenose dolphins (Tursiops truncatus) induces the same arterial aging phenotype as the serum of age-equivalent humans. We incubated conduit arteries from young and old mice with dolphin and human serum and measured endothelial function ex vivo via endothelium-dependent dilation to acetylcholine. Although young arteries incubated with serum from midlife/older adult human serum had lower endothelial function, those incubated with dolphin serum consistently maintained high endothelial function regardless of the age of the donor. Thus, studying the arterial health of dolphins could lead to potential novel therapeutic strategies to improve age-related endothelial dysfunction in humans.NEW & NOTEWORTHY We demonstrate that, unlike serum of midlife/older adult humans, age-matched dolphin serum elicits higher endothelial function ex vivo in young mouse carotid arteries, suggesting that the circulating milieu of bottlenose dolphins may be geroprotective. We propose that dolphins are a novel model to investigate potential novel therapeutic strategies to mitigate age-related endothelial dysfunction in humans.

Effect of feathers on drag in plunge-diving birds.

This study explores the impact of feathers on the hydrodynamic drag experienced by diving birds, which is critical to their foraging efficiency and survival. Employing a novel experimental approach, we analyzed the kinematics of both feathered and nonfeathered projectiles during their transition from air to water using high-speed imaging and an onboard accelerometer. The drag coefficients were determined through two methods: a direct calculation from the acceleration data and a theoretical approach fitted to the observed velocity profiles. Our results indicate that feathers significantly increase the drag force during water entry, with feathered projectiles exhibiting approximately double the drag coefficient of their smooth counterparts. These findings provide new insights into the role of avian feather morphology in diving mechanics and have potential implications for the design of bioinspired aquatic vehicles in engineering. The study also discusses the biological implications of increased drag due to feathers and suggests that factors such as body shape might play a more critical role in the diving capabilities of birds than previously understood.

Behavioral neuroscience in zebrafish: unravelling the complexity of brain-behavior relationships.

This paper reviews the utility of zebrafish (Danio rerio) as a model system for exploring neurobehavioral phenomena in preclinical research, focusing on physiological processes, disorders, and neurotoxicity biomarkers. A comprehensive review of the current literature was conducted to summarize the various behavioral characteristics of zebrafish. The study examined the etiological agents used to induce neurotoxicity and the biomarkers involved, including Aß42, tau, MMP-13, MAO, NF-Кß, and GFAP. Additionally, the different zebrafish study models and their responses to neurobehavioral analysis were discussed. The review identified several key biomarkers of neurotoxicity in zebrafish, each impacting different aspects of neurogenesis, inflammation, and neurodegeneration. Aß42 was found to alter neuronal growth and stem cell function. Tau's interaction with tubulin affected microtubule stability and led to tauopathies under pathological conditions. MMP-13 was linked to oxidative assault and sensory neuron degeneration. MAO plays a role in neurotransmitter metabolism and neurotoxicity conversion. NF-Ðšß was involved in pro-inflammatory pathways, and GFAP was indicative of neuroinflammation and astroglial activation. Zebrafish provide a valuable model for neurobehavioral research, adhering to the "3Rs" philosophy. Their neurotoxicity biomarkers offer insights into the mechanisms of neurogenesis, inflammation, and neurodegeneration. This model system aids in evaluating physiological and pathological conditions, enhancing our understanding of neurobehavioral phenomena and potential therapeutic interventions.

Evaluation of North Sea saturation procedures through divers monitoring.

BACKGROUND: Saturation diving is a standard method of intervention for commercial diving during offshore operations. Current saturation procedures achieve a high level of safety with regards to decompression sickness but still put the divers under multiple stressors: 1) Environmental stress (long confinement, heat/cold, dense gases, high oxygen levels), 2) Work stress (muscular fatigue, psychological pressure, breathing equipment, etc.), 3) venous gas emboli associated with decompression, 4) Inflammation related to oxidative stress and microparticles. We present the results of a saturation divers monitoring campaign performed in the North Sea Danish sector, on the Tyra field, during 2022. The study was supported by TotalEnergies, the field operator, and performed by Boskalis Subsea Services, the diving contractor, onboard the diving support vessel Boka Atlantis. The objective was twofold: document the level of diving stress during saturation operations in the Danish sector, and compare the performances of two saturation procedures, the Boskalis and the NORSOK procedures. MATERIALS AND METHODS: Fourteen divers volunteered for the study. The monitoring package include weight and temperature measurements, psychomotor tests (objective evaluation) and questionnaires (subjective evaluation), Doppler bubble detection and bioimpedance. The results were presented in a radar diagram that provides a general view of the situation. RESULTS: The data were analysed along 3 dimensions: work and environmental, desaturation bubbles, oxidative stress and inflammation. The results showed little or no variations from the reference values. No bubbles were detected after excursion dives and the final decompression, except for two divers with a grade 1 after arriving at surface. No statistical difference could be found between the Boskalis and the NORSOK saturation procedures. CONCLUSIONS: At a depth of 40-50 msw corresponding to the Danish sector, the two saturation procedures monitored induce no or little stress to the divers. The divers know how to manage their diet, equilibrate their hydration and pace their effort. Data available on divers' post saturation period show a recovery over the 24-48 hours following the end of the decompression. Further research should focus on diving deeper than 100 msw where a greater stress can be anticipated.