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Chemical Senses

Oxford University Press (OUP)

Preprints posted in the last 90 days, ranked by how well they match Chemical Senses's content profile, based on 32 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

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A rapid and connected test for olfactory loss screening

Moussy, E.; Fournel, A.; Daude, C.; Fieux, M.; Ferdenzi, C.; Bensafi, M.; Richard, M.

2026-07-27 otolaryngology 10.64898/2026.07.23.26358424 medRxiv
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INTRODUCTION: Despite their widespread prevalence and deleterious consequences, olfactory disorders remain little evaluated in clinical practice and neuroscientific studies, due to the lack of early, quick and reliable detection tools. To meet this demand, we developed a new connected olfactory test and evaluated its ability to discriminate dysosmia (i.e., altered sense of smell) from normosmia. METHODS: The Olfactory Screening with Connected And Rapid Detection test (OS-card, version 1.0) consisted of 8 RFID-equipped scratch-and-sniff cards interfaced with a dedicated mobile application. In this test, each micro-encapsulated odor is rated for perceived intensity on a 5-point scale and identified using a 4-alternative forced-choice procedure. The olfactory abilities of two matched samples of 25 normosmic and 25 dysosmic participants were evaluated using the OS-card 1.0 and two reference tests: the European Test for Olfactory Capabilities ETOC and the identification subtest of the Sniffin' Sticks. RESULTS: Intensity and identification OS-card scores were significantly lower in dysosmics than in normosmics. OS-card was easy to use and took less than 10 minutes to complete. OS-card scores were well correlated with ETOC scores and Sniffin' Sticks scores. According to a cross-validation approach using olfactory status categories provided by the ETOC, it was found that OS-card correctly classified 100% of the normosmic participants, 68% of the dysosmics (hyposmics and anosmics together), and 96% of the anosmics. CONCLUSION: OS-card is user friendly, rapid and reliable for detecting severe smell disorders (anosmia).

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Odors Smell Like Their Components: A Linear Framework for Predicting Olfactory Mixture Perception

Pellegrino, R.; Mayhew, E. J.; Margolis, J.; Andres, M.; Wiltschko, A. B.; Gerkin, R. C.; Mainland, J. D.

2026-07-08 neuroscience 10.64898/2026.07.03.736426 medRxiv
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Most smells, whether in food, perfume, or the environment, are complex mixtures of many odor molecules. A principled framework for modeling natural mixtures has been considered intractable because mixtures are widely assumed to generate nonlinear perceptual interactions that mirror nonlinear responses at the receptor and neural levels. We quantified perceptual interactions across 432 mixtures composed of 144 component odorants using a trained human panel, and nearly all mixtures were explained by a linear average of their component quality profiles. Within this linear modeling framework, averaging component profiles predicted mixture perception significantly better than the previous state-of-the-art and approached the ceiling set by measurement noise. Even mixtures previously reported to exhibit emergence were equally well predicted. These results suggest that the main challenge in modeling odor perception is characterizing individual components, rather than exhaustively mapping odor-odor interactions. Just as additive color mixing enabled colorimetry, linear mixing in olfaction opens the door to quantitative odorimetry, allowing mixtures to be predicted, reconstructed, and optimized computationally.

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Positive long-term outcomes of functional nasal surgery and histological findings in post-COVID-19 olfactory dysfunction

Sharma Khatiwada, A.; Pendolino, A. L.; Liu, Z.; Scarpa, B.; Grubb, M. S.; Andrews, P. J.

2026-07-23 otolaryngology 10.64898/2026.07.22.26358656 medRxiv
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Background: Olfactory dysfunction (OD) is common in COVID-19 and in a small percentage of patients it can become persistent, substantially impacting on quality of life. Effective treatment options for persistent COVID-19-related OD (C19OD) remain limited. Functional septorhinoplasty (fSRP) can improve olfaction in persistent C19OD by increasing nasal airflow to the olfactory cleft and improving olfactory epithelium (OE) stimulation. However, this implies a retained and functioning OE in C19OD patients. This study evaluates the 12-month outcomes of fSRP and investigates the histopathological correlates supporting the role of nasal airflow improvement to restore olfaction. Methods: This observational cohort study enrolled 12 patients with persistent C19OD who underwent fSRP. Olfactory function (Sniffin Sticks TDI scores) and nasal airflow were assessed at baseline, 3, 6, and 12 months. Endoscopic olfactory mucosa biopsies were obtained at baseline from 8 patients for immunohistochemical analysis. Results: fSRP led to statistically significant and clinically relevant TDI improvements at 12 months (median improvement 8.0 from baseline, p<0.005) accompanied by sustained improvement of nasal airflow (p=0.01). Histological analysis showed the presence of immature and mature olfactory sensory neurons in 3 patients (37.5%). In one specimen, intact OE was identified containing horizontal basal cells, indicating preserved regenerative capacity more than two years post-infection. Conclusions: fSRP provides sustained clinical benefits for patients with persistent C19OD. The survival of sensory neurons and progenitor cells in the olfactory mucosa beyond two years suggests a biological substrate for olfactory recovery, which may be facilitated by surgically improved nasal airflow and OE stimulation.

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Protocol for a Modified Delphi Consensus Study on the * Clinical Assessment of Children with Suspected Olfactory Dysfunction

Bhargava, E. K.; Whitcroft, K. L.; Gellrich, J.; Fishman, G.; Propst, E. J.; Zou, L.; Hummel, T.

2026-07-04 otolaryngology 10.64898/2026.07.01.26357062 medRxiv
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Background Olfactory dysfunction (OD) affects approximately 22% of the general population, yet children account for only around 2% of specialist olfactory clinic attendees -- a striking disparity that likely reflects systematic under-detection rather than lower disease prevalence. There are currently no internationally endorsed clinical guidelines governing the assessment of children with suspected OD. A recent international survey of 167 paediatric otolaryngologists across 36 countries found that more than half never perform psychophysical olfactory testing, a majority routinely order neuroimaging, and that multidisciplinary collaboration is largely lacking - findings that collectively motivate this consensus effort. Materials and Methods This is a prospectively registered, multi-round modified Delphi consensus study. A steering committee of seven international experts spanning paediatric otorhinolaryngology, chemosensory science, neuropaediatrics, and research methodology will generate an initial set of candidate consensus statements across 12 pre-defined clinical domains, derived from a structured narrative evidence review and practice-gap data. A panel of 15-25 international experts will vote anonymously over two to three sequential rounds using a 9-point Likert scale. Consensus is defined a priori as a median score [&ge;]7 with [&ge;]75% of panellists rating 7-9 and an IQR of [&le;]2. A post-Delphi virtual ratification meeting will follow voting rounds. Patient and Public Involvement (PPI) is embedded throughout: a family advisory group of 4-6 parents, caregivers, and young people with lived experience of paediatric OD, recruited in partnership with anosmie.org, will review candidate statements before Round 1, and PPI findings will inform statement framing before expert voting begins. This study was assessed using the Health Research Authority (HRA) online decision tool for England and found not to require NHS Research Ethics Committee (REC) review. The study will be conducted in accordance with the Research Governance Framework for Health and Social Care (2nd Edition). Discussion The final consensus statements and supporting methodology will be submitted for peer-reviewed publication. The study will be reported in compliance with the ACCORD and DELPHISTAR reporting standards for consensus methods. The protocol has been pre-registered prospectively on the Open Science Framework (OSF) prior to data collection.

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Functional Deorphanization and Subtype-Selective Pharmacology of Three Tyramine Receptors in the Disease Vector, Aedes aegypti

Afifi, S.; Paluzzi, J.-P. V.

2026-07-27 zoology 10.64898/2026.07.24.740580 medRxiv
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Biogenic amines such as tyramine (TA) and octopamine (OA) are central regulators of insect physiology and behaviour, acting through G protein-coupled receptors (GPCRs) to control reproduction, locomotion, metabolism, olfaction and hydromineral homeostasis. Although TA was once considered solely a biosynthetic precursor to OA, it is now recognized as an independent signaling molecule acting through distinct tyramine receptors (TARs). Owing to their invertebrate-specific roles and absence in vertebrates, TARs represent promising molecular targets for selective insecticide development. In the mosquito Aedes aegypti, a major arboviral vector of dengue and Zika viruses, the functional and pharmacological properties of TARs have not been characterized. Here, we functionally deorphanized and comparatively characterized three putative A. aegypti tyramine receptors (AaTAR1-AaTAR3) using a heterologous assay, revealing subtype-specific pharmacological profiles and antagonist sensitivities. All three receptors were robustly activated by TA in a concentration-dependent manner, whereas OA exhibited significantly lower potency on each receptor subtype, consistent with a strong preference for TA. All three TARs were unresponsive to dopamine and serotonin, even when using supraphysiological concentrations, indicating high ligand specificity. Antagonist profiling revealed pronounced subtype-specific pharmacology: yohimbine strongly suppressed AaTAR1, phentolamine most effectively inhibited AaTAR2, whereas AaTAR3 exhibited reduced sensitivity to several classical aminergic antagonists, suggesting a pharmacologically distinct subtype. These findings establish that AaTAR1, AaTAR2 and AaTAR3 are bona fide functional tyramine receptors, define their ligand selectivity and subtype-specific pharmacology, and provide a comparative framework for understanding mosquito tyraminergic signaling, highlighting their potential as targets for next-generation vector control strategies.

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Open-source benchmarking of dairy and dairy-free products

Koosis, A. O.; Cotto, C.; Kuhl, E.

2026-08-19 bioengineering 10.64898/2026.08.14.744929 medRxiv
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Dairy-free foods must reproduce diverse functions of dairy, from foam stabilization in a latte to acid-gel structure in yogurt and melt-stretch behavior in mozzarella. Public consumer benchmarks rarely compare these categories under a common protocol. Here we analyze data from the NECTAR Taste of the Industry 2026 study, a blinded, randomized, in-person evaluation of commercial dairy-free products and dairy benchmarks. The full study included 2,183 consumers and 112 products across ten categories, with 3,220 product evaluations and 79,027 recorded survey responses, including 35,762 product-linked responses. The ten categories included barista milk, butter, cheddar, cream cheese, creamer, ice cream, fluid milk, mozzarella, sour cream, and Greek style yogurt. Within each category, we compare a dairy benchmark with the dairy-free product selected post hoc as the category leader. Participants rated overall liking, flavor, texture and mouthfeel, appearance, similarity to dairy, and purchase intent on seven-point scales and completed check-all-that-apply questions. In exploratory category-specific equivalence tests using a chosen margin of {+/-}0.05 points, barista milk, creamer, and fluid milk meet this margin. Mozzarella has the largest paired deficit of -1.46 points (unadjusted, p < 0.001), followed by Greek style yogurt and butter; all three remain significant after Holm correction across the ten primary comparisons. Descriptive penalty analysis associates off-flavor, artificial or chemical notes, stale or cardboard notes, bitter taste, and lingering aftertaste with the largest reductions in liking. Together, these results establish the first open sensory benchmark for dairy and dairy-free products, demonstrate that sensory parity is already achievable in several beverage categories, and identify the product categories and sensory attributes that offer the greatest opportunities for future innovation.

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Evidence that Dogs Can Use Temporal Difference in Odorant Arrival to Discriminate Odorant Mixtures

Downie, I.; Szyszka, P.; Hall, N. J.; Edwards, T. L.

2026-07-01 animal behavior and cognition 10.64898/2026.06.26.734637 medRxiv
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In turbulent environments, odorants from different sources arrive at different times, potentially providing cues for odor source segregation. In several invertebrate species, short differences in odorant onset enable freely moving animals to discriminate odorant mixtures. In vertebrates, however, studies of sensitivity to odorant onset asynchrony have been conducted under highly constrained sampling conditions, such as with odor delivery tightly coupled to respiration. In this study, we investigated whether domestic dogs could detect odorant onset asynchrony in odorant mixtures under conditions that preserve key features of natural odor sampling. Dogs performed a discrimination task in which odor stimuli were presented as ongoing pulse trains that began independently of animal behavior, avoiding artificial synchronization of odor delivery with sniff cycles. Dogs were trained to discriminate between mixtures of two odorants with synchronous onsets and mixtures with asynchronous onsets. Of the dogs trained, one was able to discriminate odorant onset asynchronies as short as 633 ms. Dogs also displayed sensitivity to auditory stimulus onset asynchrony, discriminating auditory asynchronies as short as 30 ms. These results provide the first demonstration of temporal sensitivity in canine olfaction and the first evidence that vertebrates can use odorant onset asynchrony under conditions that permit free odor sampling.

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The nucleus of the lateral olfactory tract is required for learning odor-guided food avoidance

Lawabny, N.; Dhamshy, A.; Kreisel, T.; Licht, T.; Rokni, D.

2026-07-16 neuroscience 10.64898/2026.07.16.738920 medRxiv
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Foraging animals must continually evaluate whether potential food sources are safe to consume. Such decisions rely on both innate preferences and learned associations formed through prior experience. Consumption of a food followed by malaise or sickness leads to avoidance of that food, reflecting learned associations between sensory cues that identify a food and its negative post-ingestive consequences. Although this form of learning has been studied extensively using taste cues, taste signals arise only after oral contact, at which point exposure to potential toxins has already occurred. Olfactory cues, in contrast, provide information about potential food sources prior to consumption, yet how odors acquire aversive value remains unclear. Here, using targeted chemogenetic perturbations, we identify the nucleus of the lateral olfactory tract (NLOT), which has direct bidirectional connectivity to olfactory regions and the basolateral amygdala, as a critical circuit element for odor-aversion learning. We find that the NLOT is required for conditioned odor aversion but is dispensable for other odor-guided behaviors and for fear conditioning driven by a non-olfactory cue. Our findings identify a selective role for the NLOT in linking olfactory cues to learned aversive outcomes, that supports odor-guided behavioral decisions. Significance statementAnimals rely on smell to evaluate food safety before consuming it, yet the brain circuits that link odor cues to learned aversive outcomes remain poorly understood. Here we identify the nucleus of the lateral olfactory tract (NLOT), a largely unstudied region at the interface between olfactory and limbic circuits, as a critical and selective node for conditioned odor aversion learning. Chemogenetic perturbations of the NLOT disrupted both the acquisition and expression of odor-malaise associations, while leaving odor detection, odor discrimination, and non-olfactory fear learning intact -- revealing a previously unrecognized specialization within olfactory-amygdala circuits that supports odor-guided decisions about food safety.

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Methodological assessment of PDMS passive sampling for skin VOC collection across body sites

Kobara, S.; Huang, M.; Ilhamsyah, R.; Struk, D.; Dimandja, J.; Hesketh, P. J.; Arrubla, D. C.; Fensore, C.; Polito, C.; Kamaleswaran, R.; Esper, A.

2026-07-16 molecular biology 10.64898/2026.07.15.738701 medRxiv
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Background/ObjectivesPolydimethylsiloxane (PDMS) is a non-invasive and versatile material often used for non-invasive collection of skin-emitted volatile organic compounds (VOCs), with potential applicability in acute and pre-critical care settings. However, most existing PDMS-based methodologies rely on extensive sample preparation and environmental control, limiting their feasibility in time-sensitive clinical contexts. MethodsWe conducted a proof-of-concept pilot study in four healthy volunteers to evaluate whether a simplified skin-contact PDMS sampling procedure can capture detectable VOCs and preserve individual-level variation. PDMS strips were applied directly to the skin with minimal preparation, and collected VOCs were analyzed using gas chromatography-mass spectrometry. Donor-associated variability was assessed using Bray-Curtis dissimilarity, and variability in VOC detection was evaluated across body sites. ResultsSkin-contact PDMS sampling detected 160 VOCs across four participants. The mean within-donor Bray-Curtis dissimilarity was 0.308, compared with a mean between-donor dissimilarity of 0.347. Preliminary permutation testing showed distinguishable donor profiles (p-value = 0.004). VOC detection variability differed across body sites, with lower coefficients of variation at the forehead, neck, and wrist than at the ankle. ConclusionsUnder simplified sampling conditions, skin-contact PDMS captured individual-associated VOC profiles with lower within-donor variability than between-donor variability. These findings support the feasibility of PDMS-based skin VOC sampling in minimally controlled settings. Further validation in larger and clinically relevant cohorts is warranted to assess the utility of PDMS-sampled skin VOCs as potential biomarkers for early disease detection.

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Olfactory Dysfunction in Primary Ciliary Dyskinesia: A Systematic Review and Meta-analysis

Zubair, A.; Whitcroft, K.; Khong, G.; Bhargava, E.

2026-08-19 otolaryngology 10.64898/2026.08.17.26355624 medRxiv
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Background: Olfactory dysfunction is a recognised but poorly characterised comorbidity of Primary Ciliary Dyskinesia (PCD). No prior systematic review has synthesised its prevalence or clinical correlates. Methodology: A PRISMA compliant systematic review and meta-analysis was conducted. Five databases were searched to February 2026. Observational studies reporting olfactory function in confirmed PCD were included. Risk of Bias was assessed using the Newcastle-Ottawa Scale. A random-effects meta-analysis using the Freeman-Tukey double arcsine transformation was performed to calculate pooled prevalence with 95% confidence intervals (CI) and prediction intervals (PI). Results: Twelve studies (n=865) were included. Overall pooled prevalence of olfactory dysfunction was 43.4% (95% CI 25.2-62.5%; 95% PI 0.1-99.0%). Objective psychophysical testing yielded a significantly higher pooled prevalence of 66.1% (95% CI 55.5-76.0%; 95% PI 38.4-88.9%) compared to patient-reported outcome measures (30.5%; 95% CI 11.4-54.0%). Older age, greater sinonasal disease burden, and specific ciliary ultrastructural defects were associated with worse olfactory function. A striking discordance between objective dysfunction and subjective awareness was observed across multiple studies. Conclusions: Olfactory dysfunction is highly prevalent in PCD and substantially under-recognised by patients. Routine objective olfactory screening should be integrated into standard multidisciplinary PCD care.

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Passive acoustic monitoring of Ensiferan calling diversity in a sub-tropical forest of Northeast India.

Ghosh, A.; Borgohain, J.; War, R. M.; Rajaraman, B. K.

2026-06-17 zoology 10.64898/2026.06.14.732046 medRxiv
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Ensiferans are nocturnal insects (Order Orthoptera) that produce mating advertisement calls using stridulatory organs on modified forewings. These calls, typically made by males, are species-specific and serve as indicators of forest health. In biodiverse ecosystems like the subtropical forests, caller density is high, and ecological constraints such as intra- and interspecific acoustic competition, masking interference, and predation pressure can influence calling behavior. These pressures lead to variation in call structures and differences in spatiotemporal acoustic space use, leading to variations in community call type composition across the seasons. Passive Acoustic Monitoring (PAM), a non-invasive and cost-effective technique, is widely used for long-term monitoring in vertebrate taxa, but is less commonly applied to terrestrial invertebrates. In this study, we employed PAM to quantify acoustic diversity, acoustic space use, separation of different call types, seasonal calling patterns, and seasonal variation in call type composition among nocturnal Ensiferan callers. Year-round recordings were conducted using AudioMoth devices in the Khasi Hills of Meghalaya, part of the Indo-Burma Biodiversity Hotspot, at a 48 kHz sampling rate. Acoustic samples were processed using Raven Pro software. We identified 33 distinct call types, mutually distinctly differing in spectral, temporal, or both parameters. Principal Component Analysis revealed fine-scale separation of call types. While there were seasonal shifts in call types, with the dry season having the least number of callers, overall call type composition remained stable across pre-monsoon and monsoon seasons. Acoustic Space Use (ASU) analysis indicated greater use of lower frequency bands consistent with ground cricket presence, as well as seasonal variation in spectral occupancy. This foundational study is the first of its kind in Northeast India and demonstrates the potential of PAM in studying invertebrate soundscapes.

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Effects of acute intranasal allergen exposure on resident immune cells and sensory neurons in the mouse olfactory epithelium

Owens, R. E.; Matthews, B. E.; Mastrangelo, M. A.; Meeks, J. P.; Rowe, R. K.

2026-07-15 neuroscience 10.64898/2026.07.09.737488 medRxiv
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The main olfactory epithelium (MOE) is the primary site of olfaction and consists of multiple cell types including olfactory sensory neurons (OSNs), sustentacular cells, and immune cells. Neuroimmune interactions in epithelial tissues are critical in maintaining tissue function, but how OSNs and immune cells interact in the MOE in healthy and diseased states is largely unknown. Cellular responses in the MOE determine how and whether OSNs maintain olfactory function and are repaired or replenished following inflammatory environmental exposures. We hypothesized that acute nasal aeroallergen exposure alters immune cell function in the MOE to elicit a neuroprotective response, thereby preserving OSN function. We developed an environmental aeroallergen exposure consisting of one week of daily intranasal house dust mite extract (HDM) instillations. Spectral flow cytometry indicated only subtle changes in resident immune cells proportions and phenotypes in the MOE. Immunohistochemical evaluation did not reveal extensive changes in immune cell distribution in the sensory epithelium or lamina propria, but instead we observed increases in axonal olfactory marker protein (OMP) expression in the lamina propria, where resident immune cells are most abundant. To evaluate the effects of HDM exposure on OSN function, we performed live ex vivo Ca2+ imaging of MOEs from HDM- and sham-exposed transgenic mice using objective-coupled planar illumination (OCPI) microscopy. OSN responses to multiple odorants revealed increased chemosensory sensitivity and decreased across-trial adaptation in HDM-treated epithelia. These results indicate that short-term nasal aeroallergen exposure minimally alters immune cell phenotypes, and instead induces functional changes in OSN physiology that preserve olfactory function.

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Texture Profile Analysis and Consumer Sensory Evaluation of Plant-Based and Conventional Breaded Shrimp

Koosis, A. O.; Kuhl, E.

2026-07-20 bioengineering 10.64898/2026.07.17.739214 medRxiv
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Plant-based seafood alternatives could reduce pressure on marine ecosystems, yet texture gaps between plant-based and conventional products limit consumer adoption. This study compared the textural properties and consumer acceptance of plant-based and conventional breaded shrimp to evaluate whether instrumental texture differences predict sensory differences. Texture Profile Analysis (TPA) was performed on four breaded shrimp products (n = 14-15 replicates per product), and consumer sensory evaluation (n = 107) used a within-subjects counterbalanced design assessing hedonic ratings, Just-About-Right attributes, Check-All-That-Apply descriptors, and purchase intent. TPA revealed that plant-based shrimp exhibited significantly higher hardness (14.9 {+/-} 1.0 N vs. 9.6 {+/-} 2.8 N), stiffness (592 {+/-} 40 kPa vs. 382 {+/-} 113 kPa), and chewiness (10.5 {+/-} 0.8 N vs. 2.5 {+/-} 1.1 N) compared to conventional shrimp (all p < 0.0001). However, consumer sensory evaluation revealed no significant differences between products for any hedonic attribute, JAR rating, CATA descriptor, or purchase intent (all p > 0.05 after FDR correction). Despite 1.6-fold greater hardness and 4.2-fold greater chewiness, plant-based breaded shrimp received comparable hedonic ratings to conventional shrimp, suggesting that the breaded format masks mechanical texture differences. Achieving TPA parity may not be necessary for consumer acceptance in breaded seafood applications. HighlightsO_LIPlant-based shrimp is 1.6x harder and 4.2x chewier than conventional C_LIO_LIConsumers reported no significant sensory differences between products C_LIO_LIBreaded format masks instrumental texture differences C_LIO_LITPA parity may not be required for consumer acceptance C_LI

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The optical origin of the human skin color 'banana' in CIELAB space

Harunani, M.; Han, Y. J.; Shen, M.; Sparkman, B.; Chen, D.; Nussinov, Z.; Shmuylovich, L.

2026-06-18 bioengineering 10.64898/2026.06.16.732713 medRxiv
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Human skin colors occupy a characteristic banana-shaped region in CIE L*a*b* space, but why skin color coordinates are restricted to this region and how they relate to melanin and blood remain incompletely understood. We developed a physics-based framework linking skin chromophore content to colorimeter-derived skin color coordinates using two complementary three-layer light transport models. Across physiologic ranges of epidermal melanosome volume fraction and dermal blood volume fraction, simulated reflectance spectra were converted to CIE L*a*b* coordinates and compared with human skin color measurements from the International Skin Spectra Archive. Physiologic variation in melanin and blood reproduced the observed banana-shaped locus and revealed distinct chromophore-specific trajectories. Iso-melanin trajectories became progressively more linear as melanin increased, whereas iso-blood trajectories retained the curvature of the skin color locus. As melanin increased, perceptible color differences from blood volume changes were reduced, providing a mechanistic explanation for reduced erythema visibility in highly pigmented skin. These relationships were stable across plausible variations in layer thickness and tissue oxygenation and agreed with external validation data. The framework also identified when the Individual Typology Angle is confounded by blood or distorted by dermal melanin. Together, these findings establish a mechanistic optical basis for interpreting colorimeter-derived skin color coordinates.

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The formation and content of odor memory from childhood

Dejou, J.; Bensafi, M.; Didier, A.; Mandairon, N.

2026-07-21 neuroscience 10.64898/2026.07.16.738999 medRxiv
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As illustrated by Marcel Prousts madeleine, childhood olfactory autobiographical memory carries a stronger positive emotional valence than memories associated with other senses. However, little is known about its content or the conditions of encoding and maintenance. Here, we asked 647 participants to freely recall and characterize their earliest childhood olfactory memory. We found that this memory is typically encoded around age six, involves pleasant odors embedded within rich multisensory contexts, and retains a strong positive emotional valence despite age-related declines in some experiential qualities. The most frequently reported scenes took place at home, in the presence of the mother, and were predominantly associated with food-related odors, although natural-vegetation odors were also commonly reported. By contrast, the non-olfactory memory is encoded earlier, visually dominated, less multisensory, less pleasant, and more frequently associated with institutional settings and friends. These findings characterize childhood olfactory memory and highlight its distinctive content among autobiographical memories.

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A Pubic Hair Is 172 Times More Pubic Than a Scalp Hair

Ogata, N.; MATSUDA, T.

2026-07-01 bioengineering 10.64898/2026.06.25.734686 medRxiv
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Human hair is a common contaminant in GMP-controlled manufacturing environments, and its identification is important for contamination source investigation and corrective action. Because human hair can originate from multiple body sites, it is often necessary to determine not only the species of origin but also the anatomical source of the hair. Conventional forensic approaches distinguish scalp hair from body hair by microscopic examination of cuticle patterns, medullary structure, cross-sectional morphology, and pigment distribution. However, these methods depend on examiner expertise, are difficult to apply to damaged specimens, and provide limited quantitative information. In this study, we developed a proteomics-based approach for distinguishing scalp hair from pubic hair using identical sample preparation and analytical workflows. Comparative proteomic analysis identified keratin-associated proteins KAP 4-3 and KAP 9-6 as enriched in scalp hair, whereas cuticular keratins Ha7 and Ha8 were strongly enriched in pubic hair. Amino acid composition analysis further revealed that scalp hair-enriched proteins were highly cysteine-rich, consistent with sulfur-rich cross-linking matrix proteins, whereas pubic hair-enriched proteins exhibited characteristics of structural keratin filaments. These results demonstrate that proteomic signatures can provide a quantitative and objective means of determining the anatomical origin of human hair and may contribute to contamination source tracing in GMP manufacturing and forensic investigations.

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Efficacy of 60 personal mosquito repellents and perfumes against Aedes aegypti mosquitoes

Ross, P. A.; Paris, V.; Warusawithana, A. L.; Romualdez, K. D. X.; Dorai, A. P. S.; Kaur, J.; Md Yatim, M. F.; Li, L.; Hoffmann, A. A.

2026-08-28 zoology 10.64898/2026.08.27.747522 medRxiv
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Personal insect repellents can offer an effective means of preventing mosquito bites. Despite a wide variety of products that claim to repel mosquitoes, relatively few studies have systematically compared their performance through standardized tests. In Australia, chemical-based repellents must be registered with the Australian Pesticides and Veterinary Medicines Authority (APVMA); however, many unregistered products with unverified effectiveness remain commercially available. Here, we tested 55 insect repellents and 5 non-repellent perfumes and deodorants sold in Australia for their protection against Aedes aegypti mosquito landings (as a proxy for bites) using arm-in-cage assays across eight human subjects. We tested 43 topical repellents (containing 18 different primary active ingredients), four wristbands, three clothing stickers, three ultrasonic devices, one garment, one repellent applied to fabric, two perfumes, two deodorants and one antiperspirant. Thirteen repellents, including all wristbands, stickers and ultrasonic devices did not provide complete protection against mosquito landings for any human subject, while a further sixteen provided complete protection for 1 hr or less on average. Repellents containing DEET, oil of lemon eucalyptus, picaridin and IR3535 as the primary active ingredient were the only products that provided more than 2 hours of complete protection, but with significant variation among products with the same active ingredient. Only 7/30 essential oil-based topical repellents and perfumes provided complete protection for greater than 1 hr. Nearly half (25/52) of the repellents subject to registration with the APVMA were unregistered despite being advertised or labelled as mosquito repellents, and these tended to be less effective than registered products. Only 5/28 repellents met or exceeded their claimed protection time. This study highlights the prevalence of unregistered and ineffective mosquito repellents on the Australian market while providing evidence for products and active ingredients that do protect against mosquito bites under laboratory conditions.

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Generation of Human Taste Bud Organoids as a Human-Mimetic Platform for Modeling Taste Perception

Chae, J.; Kwon, S. S.; Kim, J.; Moon, H.; Do, V. Q.; Zehentner, S.; Cho, H.-J.; Bhin, J.; Moon, S. J.; Kim, C. H.

2026-08-10 developmental biology 10.64898/2026.08.09.743674 medRxiv
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We established a human taste bud organoid system derived from circumvallate papillae. This model has been highly anticipated in the field of taste research, where feasible approaches for validating taste biology discovered in rodent models have been limited. Through a stepwise exploratory strategy, we systematically identified and optimized the niche factors required to maintain taste bud organoids and promote their differentiation. This human taste bud organoid system comprises Type I-IV taste receptor cells (TRCs) as well as stem/progenitor cells, and its sensory receptor cells exhibit calcium responses to taste stimuli. Using this system, we identified robust Wnt signaling as a requirement for optimal TRC fate progression, uncovered a human-specific transcriptional program in LGR5 cells, and identified previously unrecognized molecular markers for Type I TRCs. By recapitulating native human taste bud cell diversity and function, this organoid provides a tractable platform for studying human taste biology and dysfunction.

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Differential Recovery Trajectories of Emergency Otolaryngologic Conditions across the COVID-19 Pandemic: A Six-year Longitudinal Study from an Urban Emergency Center

Ogawa, M.

2026-06-23 otolaryngology 10.64898/2026.06.20.26356151 medRxiv
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Objective: The COVID-19 pandemic markedly altered social activity patterns, healthcare utilization, and the epidemiology of infectious diseases. However, its long-term impact on emergency otolaryngologic conditions remains incompletely understood. This study investigated long-term trends in emergency otolaryngologic conditions before, during, and after the COVID-19 pandemic using comprehensive data from a large urban emergency clinic in Osaka, Japan. Methods: All new otolaryngologic outpatients who visited the Chuo Emergency Medical Clinic (CEMC) in Osaka City between 2019 and 2024were retrospectively analyzed. Annual trends in absolute numbers and relative proportions of emergency otolaryngologic conditions were examined by anatomical region and disease category, using 2019 as the pre-pandemic baseline. Results: A total of 99,324 new otolaryngologic outpatients were analyzed. Overall emergency visits declined sharply to approximately half of baseline in 2020, followed by a gradual but incomplete recovery toward pre-pandemic levels by 2024. Most anatomical categories declined to 45-61% of baseline in 2020 and exhibited gradual yet incomplete recovery through 2023; in stark contrast, laryngeal conditions diverged sharply, surging beyond pre-pandemic levels after 2022. Acute infectious otorhinolaryngologic diseases fell to 23-50% of baseline in 2020 and showed variable recovery (69-103%) by 2024. Notably, laryngitis exceeded the baseline, reaching 132% in 2023, whereas epiglottic edema exhibited only a transient increase approaching the baseline in 2021. Non-infectious emergency conditions generally showed only a marginal decrease in 2020 and remained relatively stable throughout the study period, except for sudden sensorineural hearing loss (SSNHL), which dropped sharply to 39% of the baseline in 2020 and remained persistently reduced through 2024. Traumatic emergencies declined variably to 53-81% of the baseline in 2020, followed by an incomplete recovery, reaching only 55-69% by 2024. Conclusion: Emergency otolaryngologic conditions demonstrated heterogeneous recovery trajectories following the COVID-19 pandemic. While most infectious and traumatic conditions gradually but incompletely normalized, laryngeal conditions showed a distinct post-pandemic surge, and SSNHL remained persistently suppressed. These findings reveal heterogeneous, condition-specific recovery trajectories that reflect both genuine shifts in community pathogen burden, true traumatic incidence, and persistent alterations in healthcare-seeking behaviors, insights essential for resource allocation during future public health emergencies.

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The Burger Battle: The Future is Blended

Koosis, A. O.; Gardner, C. D.; Kuhl, E.

2026-06-22 bioengineering 10.64898/2026.06.17.732995 medRxiv
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Texture is one of the major barriers to acceptance of sustainable protein products, yet the relationship between instrumental texture and consumer perception remains poorly understood. Here we combined consumer sensory evaluation and texture profile analysis to identify the factors that drive burger acceptance across blended, animal-based, and plant-based formulations. A total of 472 diners evaluated beef-mushroom (n = 171), turkey (n = 100), bean (n = 100), and pea (n = 101) burgers served in Stanford University dining halls, while texture profile analysis quantified physical texture (n = 10 per product). The beef-mushroom burger achieved the highest ratings for meatiness (77.0/100), tastiness (69.4/100), and moistness (61.8/100), and 78% of consumers rated its moistness as just-about-right. Although the pea burger exhibited mechanical properties similar to the beef-mushroom burger, including indistinguishable cohesiveness values (0.53 vs. 0.53), it received substantially lower ratings for meatiness (56.1 vs. 77.0), indicating that mechanical similarity alone does not ensure consumer acceptance. Across products, moistness emerged as the primary sensory limitation, with 58% of turkey consumers and 46% of bean consumers reporting insufficient moisture. Cohesiveness showed the strongest association with perceived meatiness (r = 0.82). These findings demonstrate that successful burger reformulation requires more than mechanical matching; products must reproduce the moisture, flavor, and eating experience associated with meat. Blended burgers may represent the most practical near-term strategy for reducing meat consumption without compromising eating quality.