Search Results (95)

Background: Understanding how aroma compounds enhance monosodium glutamate (MSG) umami perception remains a critical challenge in flavor science. Methods: The umami-enhancing effects of meaty flavorings were investigated using nasal clip sensory evaluation (orthonasal blockage). Active aroma compounds were subsequently identified using gas chromatography-mass spectrometry (GC-MS). The three-dimensional structure of the umami receptor T1R1/T1R3 was constructed by homology modeling. The interaction mechanism was deciphered using molecular dynamics (MD) simulations. Results: Seafood essence S demonstrated the most potent umami enhancement. Five key compounds significantly intensified the MSG umami intensity: methional, dimethyl sulfide (DMS), D-limonene (DLE), 2,3-dimethylpyrazine, and dimethyl trisulfide. Notably, this enhancement persisted even under nasal clip conditions, revealing a novel mechanism independent of cross-modal interactions. Sulfur-containing compounds consistently demonstrated umami-enhancing effects across the evaluation conditions. MD simulations showed that aroma compounds induced allosteric remodeling of T1R1/T1R3, strengthening MSG-receptor hydrogen bonding (1.8–2.6-fold increase), reducing receptor flexibility, and stabilizing the ternary complex. Binding affinity was highest for DMS, followed by DLE and methional. Conclusion: This study provides the first receptor-level evidence that aroma compounds directly modulate MSG-taste receptor interactions through allosteric regulation, offering a novel theoretical framework for odor–taste interactions with significant implications for umami enhancer design and flavor research. Full article

Background: Hydrogen sulfide (H₂S) is an endogenously produced gaseous neurotransmitter. H₂S donors exhibited neuroprotection in oxidative-stress-related disorders in preclinical studies, but odor and short half-lives have limited their clinical use. However, endogenous H₂S stimulators with antioxidant properties have advantages over H₂S donors regarding safety and patient compliance. Empagliflozin (EMPA), a sodium–glucose cotransporter-2 (SGLT2) inhibitor widely used in the treatment of diabetes mellitus (DM), exerted similar neuroprotective and antioxidant effects as H₂S and shares common mechanisms. This study aimed to investigate the role of H₂S in the antioxidant effects of EMPA in the brain. Methods: The effects of EMPA on H₂S production and reactive oxygen species (ROS) formation were assessed ex vivo in mouse brain under normal conditions and pyrogallol-induced oxidative stress. Moreover, rats were divided into the following four groups: nondiabetic, EMPA-treated nondiabetic, streptozotocin (STZ)-induced diabetic, and EMPA-treated, STZ-induced diabetic. Endogenous H₂S and ROS levels in the brain were measured using methylene blue and chemiluminescence assays, respectively. Results: Ex vivo EMPA treatment significantly increased endogenous H₂S formation in both healthy and pyrogallol-induced oxidative stress, as well as reduced ROS formation in mouse brain; these effects were significantly reversed by the H₂S synthesis inhibitor aminooxyacetic acid (AOAA). Oral EMPA administration significantly elevated brain H₂S levels in both nondiabetic and diabetic rats and reduced ROS formation. These effects were inhibited by AOAA. Conclusions: Our study revealed a novel mechanism by which EMPA can reduce oxidative stress in neurodegenerative disorders by triggering H₂S synthesis in the brain. Full article

Background/Objectives: This study was conducted as a randomized controlled trial to evaluate the effect of breast milk odor on pain and stress levels during venous blood sampling. Method: Data were collected from 60 newborn infants consisting of a total of 30 infants in the experimental group and 30 in the control group who were hospitalized in the Intensive Care Unit between 7 December 2022 and 25 September 2023. The data were collected using the Newborn Infant Pain Scale and Premature Infant Comfort Scale forms. Results: It was observed that there was a statistically significant difference between the groups in terms of the Newborn Infant Pain Scale and Premature Infant Comfort Scale when comparing the measurements taken during the procedure and 5 min after the procedure. A strong correlation was found between the Newborn Infant Pain Scale and Premature Infant Comfort Scale scores measured 5 min after the venous blood collection procedure (r = 0.86, p = 0.01). Conclusions: Based on the results of this study, it was determined that smelling breast milk, which is one of the non-pharmacological methods that can be used in invasive or non-invasive painful procedures on newborn infants, positively affects the pain and comfort level of babies. Full article

Background/Objectives: Olfactory impairment has been proposed as an early marker for Alzheimer’s disease (AD), yet the mechanisms linking sensory decline to genetic and environmental risk factors remain unclear. We aimed to identify early biomarkers and brain network alterations associated with AD risk by multimodal analyses in humanized APOE mice. Methods: We evaluated olfactory behavior, diffusion MRI connectomics, and brain and blood transcriptomics in mice stratified by APOE2, APOE3, and APOE4 genotypes, age, sex, high-fat diet, and immune background (HN). Behavioral assays assessed odor salience, novelty detection, and memory. Elastic Net-regularized multi-set canonical correlation analysis (MCCA) was used to link behavior to brain connectivity. Blood transcriptomics and gene ontology analyses identified peripheral molecular correlates. Results: APOE4 mice exhibited accelerated deficits in odor-guided behavior and memory, especially under high-fat diet, while APOE2 mice were more resilient (ANOVA: APOE x HN, F(2, 1669) = 77.25, p < 0.001, eta squared = 0.08). Age and diet compounded behavioral impairments (diet x age: F(1, 1669) = 16.04, p < 0.001). Long-term memory was particularly reduced in APOE4 mice (APOE x HN, F(2,395) = 5.6, p = 0.004). MCCA identified subnetworks explaining up to 24% of behavioral variance (sum of canonical correlations: 1.27, 95% CI [1.18, 1.85], p < 0.0001), with key connections involving the ventral orbital and somatosensory cortices. Blood eigengene modules correlated with imaging changes (e.g., subiculum diffusivity: r = −0.5, p < 1 × 10⁻³⁰), and enriched synaptic pathways were identified across brain and blood. Conclusions: Olfactory behavior, shaped by genetic and environmental factors, may serve as a sensitive, translatable biomarker of AD risk. Integrative systems-level approaches reveal brain and blood signatures of early sensory–cognitive vulnerability, supporting new avenues for early detection and intervention in AD. Full article

Background: Access to safe and reliable water and sanitation remains a critical public health and development challenge, with rural and low-income communities being disproportionately affected by inadequate services and heightened exposure to waterborne diseases. Despite global efforts and infrastructure-based progress indicators, significant disparities persist, and these often overlook users’ perceptions of water quality, reliability, and safety. This study explores the determinants of household satisfaction with drinking water in rural areas, comparing subjective user feedback with official access data to reveal gaps in current monitoring approaches and support more equitable, user-centered water governance. Methods: This study was conducted in Kazakhstan’s Atyrau Region, where 1361 residents from 86 rural villages participated in a structured survey assessing household access to drinking water and perceptions of its quality. Data were analyzed using descriptive statistics and multinomial logistic regression to identify key predictors of user satisfaction, with results compared against official records to evaluate discrepancies between reported experiences and administrative data. Results: The field survey results revealed substantial discrepancies between official statistics and residents’ reports, with only 58.1% of respondents having in-house tap water access despite claims of universal coverage. Multinomial logistic regression analysis identified key predictors of user satisfaction, showing that uninterrupted supply and the absence of complaints about turbidity, odor, or taste significantly increased the likelihood of higher satisfaction levels with drinking water quality. Conclusions: This study underscores the critical need to align official water access statistics with household-level experiences, revealing that user satisfaction—strongly influenced by supply reliability and sensory water quality—is essential for achieving equitable and effective rural water governance. Full article

Background: Phoebe zhennan and Phoebe chekiangensis are valuable evergreen trees recognized for their unique aromas and ecological significance, yet the organ-related distribution and functional implications of aroma-active volatiles remain insufficiently characterized. Methods: In this study, we applied an integrated GC-MS-based volatile metabolomics approach combined with a relative odor activity value (rOAV) analysis to comprehensively profile and compare the volatile metabolite landscape in the seeds and leaves of both species. Results: In total, 1666 volatile compounds were putatively identified, of which 540 were inferred as key aroma-active contributors based on the rOAV analysis. A multivariate statistical analysis revealed clear tissue-related separation: the seeds were enriched in sweet, floral, and fruity volatiles, whereas the leaves contained higher levels of green leaf volatiles and terpenoids associated with ecological defense. KEGG pathway enrichment indicated that terpenoid backbone and phenylpropanoid biosynthesis pathways played major roles in shaping these divergent profiles. A Venn diagram analysis further uncovered core and unique volatiles underlying species and tissue specificity. Conclusions: These insights provide an integrated reference for understanding tissue-divergent volatile profiles in Phoebe species and offer a basis for fragrance-oriented selection, ecological trait evaluation, and the sustainable utilization of organ-related metabolic characteristics in breeding and conservation programs. Full article

Background: Congenital anosmia (CA) is a rare condition characterized by a lifelong inability to perceive odors, which significantly affects daily life and may be linked to broader neurodevelopmental alterations. This study aimed to investigate structural brain differences in patients with CA using MRI, focusing on gray matter (GM) and white matter (WM) changes and their implications for neurodevelopment. Methods: This retrospective study included 28 patients with CA and 28 age- and gender-matched healthy controls. Patients with CA were diagnosed at a single medical center between 1 January 2001 and 30 August 2024. Controls were randomly selected from an imaging database and had no history of olfactory dysfunction. Brain Magnetic Resonance Imaging (MRI)was analyzed using volumetric analysis in SPM12.GM and WM volumes were quantified across 11 anatomical brain regions based on theWFU_PickAtlas toolbox, including frontal, temporal, parietal, occipital, limbic, sub-lobar, cerebellum (anterior/posterior), midbrain, the pons, and the frontal–temporal junction. Left–right hemispheric comparisons were also conducted. Results: Patients with CA exhibited significantly smaller GM volumes compared to healthy controls (560.6 ± 114.7 cc vs. 693.7 ± 96.3 cc, p < 0.001) but larger WM volumes (554.2 ± 75.4 cc vs. 491.1 ± 79.7 cc, p = 0.015). Regionally, GM reductions were observed in the frontal (131.9 ± 33.7 cc vs. 173.7 ± 27.0 cc, p < 0.001), temporal (81.1 ± 18.4 cc vs. 96.5 ± 14.1 cc, p = 0.001), parietal (52.4 ± 15.2 cc vs. 77.2 ± 12.4 cc, p < 0.001), sub-lobar (57.8 ± 9.7 cc vs. 68.2 ± 10.2 cc, p = 0.001), occipital (39.1 ± 13.0 cc vs. 57.8 ± 8.9 cc, p < 0.001), and midbrain (2.0 ± 0.5 cc vs. 2.3 ± 0.4 cc, p = 0.006) regions. Meanwhile, WM increases were notable in the frontal(152.0 ± 19.9 cc vs. 139.2 ± 24.0 cc, p = 0.027), temporal (71.5 ± 11.5 cc vs. 60.8 ± 9.5 cc, p = 0.001), parietal (75.8 ± 12.4 cc vs. 61.9 ± 11.5 cc, p < 0.001), and occipital (58.7 ± 10.3 cc vs. 41.9 ± 7.9 cc, p < 0.001) lobes. A separate analysis of the left and right hemispheres revealed similar patterns of reduced GM and increased WM volumes in patients with CA across both sides. An exception was noted in the right cerebellum-posterior, where patients with CA showed significantly greater WM volume (5.625 ± 1.667 cc vs. 4.666 ± 1.583 cc, p = 0.026). Conclusions: This study demonstrates widespread structural brain differences in individuals with CA, including reduced GM and increased WM volumes across multiple cortical and sub-lobar regions. These findings suggest that congenital olfactory deprivation may impact brain maturation beyond primary olfactory pathways, potentially reflecting altered synaptic pruning and increased myelination during early neurodevelopment. The involvement of the cerebellum further implies potential adaptations beyond motor functions. These structural differences may serve as potential neuroimaging markers for monitoring CA-associated cognitive or emotional comorbidities. Full article

Background/Objectives: Outbreaks of highly pathogenic avian influenza virus (AIV) result in significant financial losses and the death or depopulation of millions of domestic birds. Early and rapid detection and surveillance are needed to slow the spread of AIV and prevent its spillover to humans. The volatile metabolome (i.e., the pattern of volatile metabolites emitted by a living subject) represents one such source of health information that can be monitored for disease diagnosis. Indeed, dogs have been successfully trained to recognize patterns of “body odors” associated with many diseases. Because little is known regarding the mechanisms involved in the alteration of the volatile metabolome in response to health perturbation, questions still arise regarding the specificity, or lack thereof, of these alterations. Methods: To address this concern, we experimentally infected twenty mallard ducks with one of two different strains of low-pathogenic AIV (ten ducks per strain) and collected cloacal swabs at various time points before and after infection. Results: Headspace analyses revealed that four volatiles were significantly altered following infection, with distinct profiles associated with each viral strain. The volatiles that differed between strains among post-infection sampling periods included ethylbenzyl ether (p = 0.00006), 2-phenoxyethanol (p = 0.00017), 2-hydroxybenzaldehyde (p = 0.00022), and 6-methyl-5-hepten-2-one (p = 0.00034). Conclusions: These findings underscore that AIV-induced changes to the volatile metabolome are strain-specific, emphasizing the need for disease-specific profiling in diagnostic development. Full article

Houttuynia cordata is a culinary herb from Asia. Its edible rhizomes and leaves have a fishy aroma, the molecular background of which was unknown. A comparative aroma extract dilution analysis applied to fresh rhizomes and leaves resulted in 44 and 41 odorants, respectively, 38 of which were present with FD factors ≥1 in both samples. The odorant with the highest FD factors, whether in the rhizomes or leaves, was identified as metallic, soapy, fishy smelling 3-oxododecanal. Toward clarifying its tautomeric composition, quantum calculations suggested a predominance of the enol forms in the plant. However, the form perceived at the sniffing port during GC–O remained unclear. Full article

Background: Breast cancer remains a leading cause of cancer-related deaths despite advances in its diagnosis and treatment. Accurate evaluation of the response to neoadjuvant chemotherapy (NAC), especially in HER2-positive and triple-negative subtypes, is critical. The current methods, including imaging and liquid biopsies, have limitations. N-NOSE, a novel urine-based cancer screening test using Caenorhabditis elegans (C. elegans) chemotaxis, offers a non-invasive alternative. This study investigates the potential of N-NOSE to predict the NAC response in breast cancer patients for improved treatment evaluations. Materials and Methods: This prospective study enrolled 36 breast cancer patients undergoing NAC and surgery to assess the predictive power of the N-NOSE method using urine samples. A chemotaxis analysis of C. elegans was used to calculate the index reduction scores (IRS1–3), reflecting the changes in tumor-related odorants across the treatment stages. Results: Between August 2020 and May 2023, 36 breast cancer patients were enrolled to evaluate the predictive value of N-NOSE IRSs for NAC response. A pathological complete response (pCR) was achieved in 36.1% of the patients. Among the three IRS types analyzed in the 35 patients, IRS3, which showed the IRS at pre-treatment minus that after surgery, showed the highest predictive performance for a pCR, with an AUC of 0.75, indicating its potential utility as a non-invasive biomarker for treatment response evaluations. Conclusions: Index reduction scores evaluated using the N-NOSE method may reflect the efficacy of NAC in breast cancer patients. Future large-scale and multi-institutional prospective studies are warranted. Full article

Odorant receptors (ORs) constitute the largest family of G protein-coupled receptors (GPCRs), with nearly 400 receptors identified in humans. The “omics” era has revealed an unexpected expression of ORs beyond olfactory tissues. For many decades these receptors were neglected from cancer research, largely due to the assumption that their expression in cancerous tissues was a background leakage, unrelated to conventional cancer pathways such as cell replication, differentiation, or DNA damage response. The Cancer Genome Atlas (TCGA) data shows, however, that OR expression profiles are specific to each tumor type. This evidence supports that ORs may be related to tumor malignancy. In this review, we explore the extranasal expression of ORs in cancer and discuss the potential implications of their presence in cancerous tissues. Full article

Background/Objectives: G protein-coupled trace amine-associated receptors (TAARs) belong to a family of biogenic amine-sensing receptors. TAAR1 is the best-investigated receptor of this family, and TAAR1 agonists are already being tested in clinical studies for the treatment of schizophrenia, anxiety, and depression. Meanwhile, other TAARs (TAAR2, TAAR5, TAAR6, TAAR8, and TAAR9 in humans) are mostly known for their olfactory function, sensing innate odors. At the same time, there is growing evidence that these receptors may also be involved in brain function. TAAR8 is the least studied TAAR family member, and currently, there is no data on its function in the mammalian central nervous system. Methods: We generated triple knockout (tTAAR8-KO) mice lacking all murine Taar8 isoforms (Taar8a, Taar8b, and Taar8c) using CRISPR-Cas9 technology. In this study, we performed the first phenotyping of tTAAR8-KO mice for behavioral, electrophysiological, and neurochemical characteristics. Results: During the study, we found a number of alterations specific to tTAAR8-KO mice compared to controls. tTAAR8-KO mice demonstrated better short-term memory, more depressive-like behavior, and higher body temperature. Also, we observed changes in the dopaminergic system, brain electrophysiological activity, and adult neurogenic functions in mice lacking Taar8 isoforms. Conclusions: Based on the data obtained, it can be assumed that the physiological TAAR8 role is not limited only to the innate olfactory function, as previously proposed. TAAR8 could be involved in brain function, in particular in dopamine function regulation. Full article

Background and Objectives: Halitosis poses a clinical and psychosocial burden, particularly in orthodontic contexts where plaque retention can exacerbate odor production. This cross-sectional study aimed to compare halitosis and oral health-related quality of life (OHRQoL) in three distinct groups: patients wearing removable clear aligners, patients with lingual orthodontic brackets, and non-orthodontic controls. We further explored dietary factors (frequent snacking vs. infrequent snacking) to identify their influence on halitosis severity and self-perceived well-being. Methods: A total of 162 participants (55 aligners, 58 lingual brackets, 49 controls) were recruited. Halitosis was assessed by the Halitosis Associated Life-Quality Test (HALT) questionnaire (range 0–100) and an organoleptic evaluation (range 0–5). OHRQoL was examined with the OHIP-14 instrument (range 0–56). Data on frequent vs. infrequent snacking were also recorded. One-way ANOVAs with Tukey’s post hoc and chi-square tests were utilized for group comparisons. Spearman’s correlation examined relationships between HALT scores, organoleptic measures, and OHIP-14. A significance threshold of p < 0.05 was adopted. Results: Aligner users demonstrated lower mean HALT scores (31.7 ± 5.8) compared to the lingual group (37.4 ± 6.2, p = 0.001) and controls (34.6 ± 6.0, p = 0.039). Lingual bracket wearers had the highest mean organoleptic score (2.4 ± 0.6, p < 0.001). Frequent snackers exhibited worse HALT outcomes (36.9 ± 6.3) than infrequent snackers (32.6 ± 5.9, p = 0.005). A correlation analysis showed a moderate positive correlation (r = +0.52, p < 0.001) between HALT and organoleptic scores and a strong negative relationship (r = –0.63, p < 0.001) between HALT and OHIP-14. Conclusions: Removable aligner use correlated with lower self-reported halitosis and better OHRQoL relative to lingual brackets. Frequent snacking appeared to aggravate halitosis across all groups. These findings emphasize the importance of tailored oral hygiene measures, dietary counseling, and orthodontic appliance selection to mitigate halitosis and enhance overall well-being. Full article

Background: Chemosensation in ticks opens a novel and unique field for scientific research. This study highlights ticks’ chemosensory system to comprehend its host-searching behavior and other integrated chemistry and biology involving Haller’s structure. Methodology: This study combines microanatomical, electrophysiological, and behavioral experiments to investigate the role of Haller’s organ in adult ticks in response to different classes of organic compounds. Results: We showed the microscopic anatomy of Haller’s organ in Haemaphysalis darjeeling, present at the terminal segment of the first pair of appendages. Haller’s structure serves a vital function in perceiving odor. The electrophysiological activity of adult ticks to different classes of organic compounds via electroscutumography was explored at five different concentrations: w/v 0.001, 0.01, 0.1, 1.0, and 2.0%. Among 55 organic compounds, moderate to high stimulation was recorded with pyruvate (13.28 mv at 2%), ammonia (12.26 mv at 2%), benzoic acid (1.99 mv at 0.001%), isobutyric acid (1.39 mv at 0.001%), 2,6-dichlorophenol (1.34 mv at 0.001%), p-Tolualdehyde (1.26 mv at 2%), tetradecane (1.23 mv at 2%), docosane (1.17 mv at 2%), citronellal (1.13 mv at 0.1%), isopropyl acetate (1.05 mv at 0.01%), cyclohexanol (1.03 mv at 2%), 1-octane-3-ol (1.02 mv at 2%), and 1-octanol (1.01 mv at 0.001%). Olfactometric bioassays at w/v 2.0% concentration further confirmed that ammonia, pyruvate, 1-octane-3-ol, hematin porcine, p-Tolualdehyde, methyl salicylate, uric acid, tetradecane, carbon dioxide, propanoic acid, 3-hexanol, hexanoic acid, adenine, 2,6-dichlorophenol, hexadecane, heptanoic acid, pentanoic acid, octadecane, guanine, and nonanoic acid acted as strong attractants, while citronellal, eugenol, butyric acid, geraniol, benzaldehyde, and tiglic aldehyde showed an active repellent effect against the tick species. Conclusions: This investigation provides knowledge of the olfactory sensilla of Haller’s structure as biosensors behind tick olfaction and the possibility for chemical detection of diverse attractants and repellents for future development of anti-tick compounds. Full article

Background: Previous studies have demonstrated that involuntary smoking (e.g., secondhand smoke [SHS] and thirdhand smoke [THS]) is not only associated with an increased risk of several physical health problems, such as cardiovascular disease and cancer, but also impacts mental health, including depression and anxiety. However, the relationships between SHS and THS exposure and non-suicidal self-injury (NSSI), suicidal ideation (SI), and suicide attempts (SAs) remain unclear. Methods: Participants were recruited at a Chinese vocational college via voluntary online surveys conducted on campus. Self-reported SHS exposure was determined by the frequency of contact with smokers or detecting tobacco odors in living environments, while THS was assessed through regular contact with smoker-contaminated surfaces (e.g., clothing, furniture, textiles). Logistic regression analysis was performed to evaluate the associations of SHS and THS exposure with the prevalence of NSSI, SI, and SAs in never-smoking participants. Results: The study included 5716 participants (mean age = 19.3 years; females, 85.4%). The prevalence of SHS and THS exposure was 87.6% and 77.4%, with 8.8% reporting ≥15 min of SHS exposure on at least one day per week. After controlling for potential covariates, exposure to SHS (≥15 min on at least one day per week) was significantly associated with the odds of SAs (OR [95%CI] = 1.85 [1.17–2.91]). Additionally, daily THS exposure was significantly associated with increased past-year NSSI prevalence (2.35 [1.29–4.28]) compared to those without THS exposure, with similar associations observed for SI (2.11 [1.28–3.48]) and SAs (2.40 [1.23–4.69]). Conclusions: Exposure to SHS and THS was significantly associated with increased likelihood of NSSI, SI, and SAs among young adults at a Chinese vocational college. Further studies are needed to validate these associations across more diverse populations. Full article