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The webinar series and workshop titled "Trust Your Gut: Establishing Confidence in Gastrointestinal Models - An Overview of the State of the Science and Contexts of Use" was co-organized by NICEATM, NIEHS, FDA, EPA, CPSC, DoD, and the Johns Hopkins Center for Alternatives to Animal Testing (CAAT) and hosted at the National Institutes of Health in Bethesda, MD, USA on October 11-12, 2023. New approach methods (NAMs) for assessing issues of gastrointestinal tract (GIT)- related toxicity offer promise in addressing some of the limitations associated with animal-based assessments. GIT NAMs vary in complexity, from two-dimensional monolayer cell line-based systems to sophisticated 3-dimensional organoid systems derived from human primary cells. Despite advances in GIT NAMs, challenges remain in fully replicating the complex interactions and processes occurring within the human GIT. Presentations and discussions addressed regulatory needs, challenges, and innovations in incorporating NAMs into risk assessment frameworks; explored the state of the science in using NAMs for evaluating systemic toxicity, understanding absorption and pharmacokinetics, evaluating GIT toxicity, and assessing potential allergenicity; and discussed strengths, limitations, and data gaps of GIT NAMs as well as steps needed to establish confidence in these models for use in the regulatory setting. [ABSTRACT FROM AUTHOR]

The Earth's polar regions are low rates of inter‐ and intraspecific diversification. An extreme mammalian example is the Arctic ringed seal (Pusa hispida hispida), which is assumed to be panmictic across its circumpolar Arctic range. Yet, local Inuit communities in Greenland and Canada recognize several regional variants; a finding supported by scientific studies of body size variation. It is however unclear whether this phenotypic variation reflects plasticity, morphs or distinct ecotypes. Here, we combine genomic, biologging and survey data, to document the existence of a unique ringed seal ecotype in the Ilulissat Icefjord (locally 'Kangia'), Greenland; a UNESCO World Heritage site, which is home to the most productive marine‐terminating glacier in the Arctic. Genomic analyses reveal a divergence of Kangia ringed seals from other Arctic ringed seals about 240 kya, followed by secondary contact since the Last Glacial Maximum. Despite ongoing gene flow, multiple genomic regions appear under strong selection in Kangia ringed seals, including candidate genes associated with pelage coloration, growth and osmoregulation, potentially explaining the Kangia seal's phenotypic and behavioural uniqueness. The description of 'hidden' diversity and adaptations in yet another Arctic species merits a reassessment of the evolutionary processes that have shaped Arctic diversity and the traditional view of this region as an evolutionary freezer. Our study highlights the value of indigenous knowledge in guiding science and calls for efforts to identify distinct populations or ecotypes to understand how these might respond differently to environmental change. [ABSTRACT FROM AUTHOR]

Sea ice primary production is considered a valuable energy source for Arctic marine food webs, yet the extent remains unclear through existing methods. Here we quantify ice algal carbon signatures using unique lipid biomarkers in over 2300 samples from 155 species including invertebrates, fish, seabirds, and marine mammals collected across the Arctic shelves. Ice algal carbon signatures were present within 96% of the organisms investigated, collected year-round from January to December, suggesting continuous utilization of this resource despite its lower proportion to pelagic production. These results emphasize the importance of benthic retention of ice algal carbon that is available to consumers year-round. Finally, we suggest that shifts in the phenology, distribution and biomass of sea ice primary production anticipated with declining seasonal sea ice will disrupt sympagic-pelagic-benthic coupling and consequently the structure and the functioning of the food web which is critical for Indigenous Peoples, commercial fisheries, and global biodiversity. Koch and Brown et al. led a collaborative and comprehensive synthesis that shows the transfer of ice algal carbon is widespread throughout the Arctic marine food web and contributes to supporting organisms throughout the dark winter months [ABSTRACT FROM AUTHOR]

The ringed seal is a small phocid seal that has a northern circumpolar distribution. It has long been recognized that body size is variable in ringed seals, and it has been suggested that ecotypes that differ in size exist. This study explores patterns of body size (length and girth) and age-at-maturity across most of the Arctic subspecies' range using morphometric data from 35 sites. Asymptotic lengths varied from 113 to 151 cm, with sites falling into five distinct size clusters (for each sex). Age-at-maturity ranged from 3.1 to 7.4 years, with sites that had early ages of sexual maturity generally having small length-at-maturity and small final body length. The sexes differed in length at some sites, but not in a consistent pattern of dimorphism. The largest ringed seals occurred in western Greenland and eastern Canada, and the smallest occurred in Alaska and the White Sea. Latitudinal trends occurred only within sites in the eastern Canadian Arctic. Girth (with length and season accounted for) was also highly variable but showed no notable spatial pattern; males tended to be more rotund than females. Genetic studies are needed, starting with the "giants" at Kangia (Greenland) and in northern Canada to determine whether they are genetically distinct ecotypes. Additional research is also needed to understand the ecological linkages that drive the significant regional size differences in ringed seals that were confirmed in this study, and also to understand their implications with respect to potential adaptation to climate change. [ABSTRACT FROM AUTHOR]

Mercury is found in Arctic marine mammals that are important in the diet of northern Indigenous peoples. The objectives of the present long‐term study, spanning a 45‐yr period, were to 1) investigate the temporal trends of total mercury (THg; muscle and liver) and selenium (Se; liver) in ringed seals (Pusa hispida) from different regions of the Canadian Arctic; and 2) examine possible relationships with age, diet, and climate parameters such as air temperature, precipitation, climatic indices, and ice‐coverage. Ringed seals were collected by hunters in northern communities in the Beaufort Sea, Central Arctic, Eastern Baffin Island, Hudson Bay, and Ungava/Nunatsiavut regions (Canada) between 1972 and 2017. Mercury levels did not change through time in seal liver, but THg levels in muscle decreased in seals from Hudson Bay (−0.91%/yr) and Ungava/Nunatsiavut (−1.30%/yr). Carbon stable isotope values in seal muscle decreased significantly through time in 4 regions. Selenium‐to‐THg ratios were found to be >1 for all years and regions. Variation partitioning analyses across regions indicated that THg trends in seals were mostly explained by age (7.3–21.7%), climate parameters (3.5–12.5%), and diet (up to 9%); climate indices (i.e., Arctic and North Atlantic Oscillations, Pacific/North American pattern) explained the majority of the climate portion. The THg levels had a positive relationship with Arctic Oscillation for multiple regions. Associations of THg with air temperature, total precipitation, and sea‐ice coverage, as well as with North Atlantic Oscillation and Pacific/North American pattern were found to vary with tissue type and geographical area. Environ Toxicol Chem 2020;39:2462–2474. © 2020 Her Majesty the Queen in Right of Canada. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Fisheries and Oceans Canada. [ABSTRACT FROM AUTHOR]

Capelin (Mallotus villosus), a sub-Arctic forage fish, has become abundant in the Canadian Arctic in recent decades, with consistent spawning documented; however, the trophic role of capelin in these systems is unknown. We investigated the diets of small, immature (70–129 mm), medium, mature (130–174 mm), and large, mature (175–219 mm) capelin in Pangnirtung Fjord, Nunavut during and prior to spawning in June–July, 2015–2016 using stomach contents and stable isotopes, respectively. Ontogenetic niche shifts were observed in both cases. Small, immature capelin consumed predominantly small copepods (primarily Clausocalanidae) and had a narrow isotopic niche (SEAC: 0.11 ‰2). In contrast, medium-sized, mature capelin consumed a mix of Calanus copepods, amphipods, and mysids and had a broad isotopic niche (SEAC range: 0.23–0.51 ‰2), while large, mature capelin consumed higher proportions of large prey types (primarily Calanus hyperboreus and amphipods) and had a narrower isotopic niche (SEAC range: 0.09–0.26 ‰2). A higher percentage (by dry biomass) of capelin eggs (73–100%) were consumed by mature capelin in 2016, when ice cover in the fjord delayed the initiation of sampling by ~ 10 days after spawning had begun, relative to 2015 (0–9%). Non-egg prey types primarily consisted of amphipods (77–100% by dry biomass, mostly ice-associated Apherusa glacialis) in 2016 and primarily pelagic Calanus copepods (64–99%) in 2015. As capelin diet was broadly similar to other Arctic forage fishes, such as polar cod (Boreogadus saida), high dietary overlap may occur. Findings provide baseline data to examine future changes in capelin diet as well as their trophic interactions in the Canadian Arctic. [ABSTRACT FROM AUTHOR]

Individual specialization ( IS), where individuals within populations irrespective of age, sex, and body size are either specialized or generalized in terms of resource use, has implications on ecological niches and food web structure. Niche size and degree of IS of near-top trophic-level marine predators have been little studied in polar regions or with latitude. We quantified the large-scale latitudinal variation of population- and individual-level niche size and IS in ringed seals ( Pusa hispida) and beluga whales ( Delphinapterus leucas) using stable carbon and nitrogen isotope analysis on 379 paired ringed seal liver and muscle samples and 124 paired beluga skin and muscle samples from eight locations ranging from the low to high Arctic. We characterized both within- and between-individual variation in predator niche size at each location as well as accounting for spatial differences in the isotopic ranges of potential prey. Total isotopic niche width ( TINW) for populations of ringed seals and beluga decreased with increasing latitude. Higher TINW values were associated with greater ecological opportunity (i.e., prey diversity) in the prey fish community which mainly consists of Capelin ( Mallotus villosus) and Sand lance ( Ammodytes sp.) at lower latitudes and Arctic cod ( Boreogadus saida) at high latitudes. In beluga, their dietary consistency between tissues also known as the within-individual component ( WIC) increased in a near 1:1 ratio with TINW (slope = 0.84), suggesting dietary generalization, whereas the slope (0.18) of WIC relative to TINW in ringed seals indicated a high degree of individual specialization in ringed seal populations with higher TINWs. Our findings highlight the differences in TINW and level of IS for ringed seals and beluga relative to latitude as a likely response to large-scale spatial variation in ecological opportunity, suggesting species-specific variation in dietary plasticity to spatial differences in prey resources and environmental conditions in a rapidly changing ecosystem. [ABSTRACT FROM AUTHOR]

As part of the Canadian contribution to the International Polar Year (IPY), several major international research programs have focused on offshore arctic marine ecosystems. The general goal of these projects was to improve our understanding of how the response of arctic marine ecosystems to climate warming will alter food web structure and ecosystem services provided to Northerners. At least four key findings from these projects relating to arctic heterotrophic food web, pelagic-benthic coupling and biodiversity have emerged: (1) Contrary to a long-standing paradigm of dormant ecosystems during the long arctic winter, major food web components showed relatively high level of winter activity, well before the spring release of ice algae and subsequent phytoplankton bloom. Such phenological plasticity among key secondary producers like zooplankton may thus narrow the risks of extreme mismatch between primary production and secondary production in an increasingly variable arctic environment. (2) Tight pelagic-benthic coupling and consequent recycling of nutrients at the seafloor characterize specific regions of the Canadian Arctic, such as the North Water polynya and Lancaster Sound. The latter constitute hot spots of benthic ecosystem functioning compared to regions where zooplankton-mediated processes weaken the pelagic-benthic coupling. (3) In contrast with another widely shared assumption of lower biodiversity, arctic marine biodiversity is comparable to that reported off Atlantic and Pacific coasts of Canada, albeit threatened by the potential colonization of subarctic species. (4) The rapid decrease of summer sea-ice cover allows increasing numbers of killer whales to use the Canadian High Arctic as a hunting ground. The stronger presence of this species, bound to become a new apex predator of arctic seas, will likely affect populations of endemic arctic marine mammals such as the narwhal, bowhead, and beluga whales. [ABSTRACT FROM AUTHOR]

Change and variability in the timing and magnitude of sea ice geophysical and thermodynamic state have consequences on many aspects of the arctic marine system. The changes in both the geophysical and thermodynamic state, and in particular the timing of the development of these states, have consequences throughout the marine system. In this paper we review the 'consequences' of change in sea ice state on primary productivity, marine mammal habitats, and sea ice as a medium for storage and transport of contaminants and carbon exchange across the ocean-sea-ice-atmosphere interface based upon results from the International Polar Year. Pertinent results include: 1) conditions along ice edges can bring deep nutrient-rich 'pacific' waters into nutrient-poor surface waters along the arctic coast, affecting local food webs; 2) both sea ice thermodynamic and dynamic processes ultimately affect ringed seal/polar bear habitats by controlling the timing, location and amount of surface deformation required for ringed seal and polar bear preferred habitat 3) the ice edges bordering open waters of flaw leads are areas of high biological production and are observed to be important beluga habitat. 4) exchange of climate-active gases, including CO, is extremely active in sea ice environments, and the overall question of whether the Arctic Ocean is (or will be) a source or sink for CO will be dependent on the balance of competing climate-change feedbacks. [ABSTRACT FROM AUTHOR]

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This paper presents the development and evaluation of a high volume slit nozzle virtual impactor that can be used to concentrate coarse particles (2.5-10 θ m) for inhalation studies. A variety of physical design and flow parameters were evaluated for their effects on the virtual impactor performance. To increase the impactor sampling flow, both multinozzle and longer slit configurations were developed and tested. The use of a longer slit nozzle made it possible to increase the inlet flow more effectively than using multiple nozzles. The effect of the slit nozzle length (from 0.762 cm up to 6.35 cm) on the impactor performance was examined. It was observed that increasing the slit length did not significantly diminish the performance of the impactor to concentrate coarse particles. Furthermore, a wider slit (W[sub 1] = 0.363 cm) that operates at a slightly higher pressure drop was used to increase the sampling flow rate. Although the wider slit presented greater losses for fine particles, the concentration factor for coarse particles was just as good as with the original narrower slit (W[sub 1] = 0.305 cm). Finally, it was demonstrated that a single-stage slit impactor (L = 6.35 cm, W[sub 1] = 0.363 cm, Q[sub 0] = 870 L/min) can be used to increase the coarse particle concentration by a factor of 15 and to supply a flow of 43.5 L/min for animal or human exposure studies. A higher concentration factor, up to 50, was achieved by using a smaller minorto-total flow ratio. [ABSTRACT FROM AUTHOR]

Outlines the evaluation of student-led group work as the major vehicle for a professional course in education. Aims of the course; Implementation of group work; Role of the tutor.

Head and neck surgeons are familiar with the technique of identifying motor nerves in the head and neck region by using electrical stimulation especially in the identification of the facial and the spinal accessory nerves. The identification of the motor laryngeal nerves by electrical stimulation intra-operatively has been described; but, the difficulty of visualization of intrinsic laryngeal muscle movement has prevented the wide spread use of this technique. This paper will introduce a simple, safe and reliable method to allow the surgeon to recognize true vocal cord movement while stimulating the recurrent laryngeal nerve. The movement of a two inch 27 gauge needle placed through the cricothyroid membrane into the ipsilateral true vocal cord permits identification of intrinsic laryngeal muscle movement during electrical stimulation of the recurrent laryngeal nerve. This method has been successfully used in confirming conductivity of the laryngeal nerve during thyroid surgery, Zenker's diverticulum surgery, cricotracheal trauma and recurrent nerve neurectomy for spasmodic dysphonia. [ABSTRACT FROM AUTHOR]

An obituary for former national president of Australian Veterinary Association Ron Hyne is presented.