Chemical Senses最新文献

Many volatile organic compounds (VOCs) are used to produce various commercial products with aromas mimicking natural products. The VOCs responsible for aromas have been identified from many natural products. The current major strategy is to analyze chemical compositions and aroma qualities of individual VOCs using gas chromatography/mass spectrometry (GC/MS) and GC-olfactometry. However, such analyses cannot determine whether candidate VOCs contribute to the characteristic aroma in mixtures of many VOCs. In this study, we developed a GC/MS-based VOC collection/omission system that can modify the VOC compositions of samples easily and rapidly. The system is composed of GC/MS with a switching unit that can change gas flow routes between MS and a VOC collection device. We first applied this system to prepare gas samples for omission tests, and the aroma qualities of VOC mixtures with and without some VOCs were evaluated by panelists. If aroma qualities were different between the 2 samples, the omitted VOCs were likely key odorants. By collecting VOCs in a gas bag attached to the collection device and transferring some VOCs to MS, specific VOCs could be omitted easily from the VOC mixture. The system could prepare omission samples without chemical identification, preparation of each VOC, and laborious techniques for mixing VOCs, thus overcoming the limitations of previous methods of sample preparation. Finally, the system was used to prepare artificial aromas by replacing VOC compositions between different samples for screening of key odorants. In conclusion, the system developed here can improve aroma research by identifying key odorants from natural products.

Clinical assessment of an individual's sense of smell has gained prominence, but its resource-intensive nature necessitates the exploration of self-administered methods. In this study, a cohort of 68 patients with olfactory loss and 55 controls were assessed using a recently introduced olfactory test. This test involves sorting 2 odorants (eugenol and phenylethyl alcohol) in 5 dilutions according to odor intensity, with an average application time of 3.5 min. The sorting task score, calculated as the mean of Kendall's Tau between the assigned and true dilution orders and normalized to [0,1], identified a cutoff for anosmia at a score ≤ 0.7. This cutoff, which marks the 90th percentile of scores obtained with randomly ordered dilutions, had a balanced accuracy of 89% (78% to 97%) for detecting anosmia, comparable to traditional odor threshold assessments. Retest evaluations suggested a score difference of ±0.15 as a cutoff for clinically significant changes in olfactory function. In conclusion, the olfactory sorting test represents a simple, self-administered approach to the detection of anosmia or preserved olfactory function. With balanced accuracy similar to existing brief olfactory tests, this method offers a practical and user-friendly alternative for screening anosmia, addressing the need for resource-efficient assessments in clinical settings.

In this study, the transfer of odorants, namely vanilla, and garlic, into the amniotic fluid (AF) during the second trimester was investigated by examination of collected AF samples through healthy adults. Eleven AF samples were collected from pregnant women (aged 32.9 ± 4.9 yr, 16-25 wk of gestation) undergoing diagnostic amniocentesis after eating garlic oil or vanilla powder in high-fat yogurt. The control group did not receive food before amniocentesis. Two vanilla, 3 garlic, and 6 control samples were collected through amniocentesis 60-120 min after ingestion. Samples were collected at -80 °C and carefully defrosted over 12 h at the same time point. Sixteen healthy volunteers (8 males, aged 26.5 ± 5.0 yr) were asked to judge AF samples with potential garlic or vanilla odors from controls in a 2-alternative forced choice (2AFC) paradigm. Judges were able to identify vanilla in the AF samples with an estimated probability of 50%, resulting in a significant P-value of < 0.001. In contrast, the identification of garlic was unsuccessful with a P-value of 0.86, and only 2 judges were able to identify both vanilla and garlic. According to the results of this study, the vanilla odor probably passes into the amniotic fluid.

Studies on taste bud cells and brain stem relay nuclei suggest that alternative pathways convey information regarding different taste qualities. Building on the hypothesis that amiloride (epithelial Na channel antagonist)-sensitive neurons respond to palatable salt (low-concentration) and amiloride-insensitive neurons respond to aversive salt (high-concentration), we investigated the histological distribution of taste-sensitive neurons in the rostral nucleus of the solitary tract in rats and their NaCl and amiloride sensitivities. We recorded neuronal activity in extracellular single units using multi-barrel glass micropipettes and reconstructed their locations on the rostrocaudal and mediolateral axes. Seventy-three taste-sensitive neurons were categorized into the best-taste category. The amiloride sensitivities of the 31 neurons were examined for 0.1, 0.2, 0.4, and 0.8 M NaCl. The neuronal distribution of amiloride-sensitive neurons was located in the lateral region, while amiloride-insensitive neurons were located in the medial region. The amiloride-sensitive neurons responded to low salt concentrations, signaling the NaCl levels required by body fluids. Amiloride-insensitive neurons were silent at low salt concentrations but may function as warning signals for high salt concentrations. Low-threshold and/or high-response neurons were located in the rostrolateral region. In contrast, high-threshold and/or low-response neurons were located in the caudal-medial region.

Evidence for parental environments profoundly influencing the physiology, biology, and neurobiology of future generations has been accumulating in the literature. Recent efforts to understand this phenomenon and its underlying mechanisms have sought to use species like rodents and insects to model multi-generational legacies of parental experiences like stress and nutritional exposures. From these studies, we have come to appreciate that parental exposure to salient environmental experiences impacts the cadence of brain development, hormonal responses to stress, and the expression of genes that govern cellular responses to stress in offspring. Recent studies using chemosensory exposure have emerged as a powerful tool to shed new light on how future generations come to be influenced by environments to which parents are exposed. With a specific focus on studies that have leveraged such use of salient chemosensory experiences, this review synthesizes our current understanding of the concept, causes, and consequences of the inheritance of chemosensory legacies by future generations and how this field of inquiry informs the larger picture of how parental experiences can influence offspring biology.

Only a few studies have investigated olfactory function in patients with obstructive sleep apnea syndrome (OSAS) using psychophysical testing, and there is a scarcity of data regarding taste evaluation in the existing literature. The primary objectives of this study were to assess both smell and taste in patients with OSAS and to explore the correlation between the severity of symptoms and sensory perception. A total of 85 OSAS patients and a control group comprising 81 subjects were enrolled. Initial assessments included anamnesis, nasal endoscopy, and the completion of questionnaires (Epworth Sleepiness Scale, Visual Analogue Scale, Questionnaire of Olfactory Disorders, and the importance of olfaction questionnaire). The diagnosis of OSAS was confirmed by polysomnography, while nasal airflow was evaluated using rhinomanometry. Olfaction was assessed using the Sniffin' Sticks test, and the Threshold-Discrimination-Identification (TDI) score was calculated. Taste evaluation was conducted in a subgroup of participants (42 patients, 38 controls) using taste strips. The mean TDI score was 31 ± 5.6 for OSAS patients and 35 ± 4.6 for controls, indicating a significant difference (P < 0.001). Similarly, the taste score was 7 ± 3.0 for OSAS patients and 12.6 ± 3.2 for controls (P < 0.001). No correlations were observed between TDI and Apnea Hypopnea Index (AHI) (r = -0.12; P = 0.28), as well as between the taste score and AHI (r = -0.31; P = 0.22). However, a weak but significant correlation between TDI score and Epworth Sleepiness Scale was detected (r = -0.05; P = 0.002). The study revealed a significant decrease in sensory perception among patients with OSAS, though open questions persist about the pathophysiology.

Toxic puffers accumulate tetrodotoxin (TTX), a well-known neurotoxin, by feeding on TTX-bearing organisms and using it to defend themselves from predators. Our previous studies have demonstrated that toxic puffers are attracted to 5,6,11-trideoxytetrodotoxin (TDT), a nontoxic TTX analog that is simultaneously accumulated with TTX in toxic puffers and their prey. In addition, activity labeling using immunohistochemistry targeting neuronal activity marker suggests that TDT activates crypt olfactory sensory neurons (OSN) of the green spotted puffer. However, it remains to be determined whether individual crypt OSNs can physiologically respond to TDT. By employing electroporation to express GCaMP6s in OSNs, we successfully identified a distinct group of oval OSNs that exhibited a specific calcium response when exposed to TDT in green spotted puffers. These oval OSNs showed no response to amino acids (AAs), which serve as food odor cues for teleosts. Furthermore, oval morphology and surface positioning of TDT-sensitive OSNs in the olfactory epithelium closely resemble that of crypt OSNs. These findings further substantiate that TDT is specifically detected by crypt OSNs in green spotted puffer. The TDT odor may act as a chemoattractant for finding conspecific toxic puffers and for feeding TTX-bearing organisms for effective toxification.

Many common chemotherapeutics produce disruptions in the sense of taste which can lead to loss of appetite, nutritional imbalance, and reduced quality of life, especially if taste loss persists after treatment ends. Cyclophosphamide (CYP), an alkylating chemotherapeutic agent, affects taste sensitivity through its cytotoxic effects on mature taste receptor cells (TRCs) and on taste progenitor cell populations, retarding the capacity to replace TRCs. Mechanistic studies have focused primarily on taste cells, however, taste signaling requires communication between TRCs and the gustatory nerve fibers that innervate them. Here, we evaluate cyclophosphamide's effects on the peripheral gustatory nerve fibers that innervate the taste buds. Following histological analysis of tongue tissues, we find that CYP reduces innervation within the fungiform and circumvallates taste buds within 4 days after administration. To better understand the dynamics of the denervation process, we used 2-photon intravital imaging to visualize the peripheral gustatory nerve fibers within individual fungiform taste buds up to 20 days after CYP treatment. We find that gustatory fibers retract from the taste bud properly but are maintained within the central papilla core. These data indicate that in addition to TRCs, gustatory nerve fibers are also affected by CYP treatment. Because the connectivity between TRCs and gustatory neurons must be re-established for proper function, gustatory fibers should continue to be included in future studies to understand the mechanisms leading to chemotherapy-induced persistent taste loss.

A common tool to measure olfactory function is the Sniffin' Sticks Test extended version (SSET). The SSET evaluates olfactory ability by summing the scores of three subtests: Threshold, Discrimination, and Identification. Recent meta-scientific literature revealed that many psychometric instruments currently in use have not been adequately validated, leading to a measurement crisis that raises concerns about the validity of the conclusions drawn with these instruments. Two examples of the measurement crisis are (i) the use of sum scores without testing their assumptions (e.g. unidimensionality and tau-equivalence), which indicate that all subtests have the same, stable relationship with their underlying construct, and (ii) the lack of assessment of measurement invariance across groups. Here, we aim to investigate the unidimensionality and tau-equivalence assumptions, internal consistency, and measurement invariance of sex and age groups of the SSET. We tested 988 (555 females, mean ± SD: 39.75 ± 18.60 years) participants with the Italian version of the SSET. The tau-equivalent model demonstrated excellent fit indices (CFI robust = 1, TLI robust = 1, RMSEA robust = 0, SRMR = 0.013), which best explain the data, indicating that all subtests are equally important in measuring olfactory function, but not necessarily equally precise. The results also revealed full measurement invariance across age groups and configural, partial metric, and scalar invariance across sexes, indicating that the use of latent means to compare sex groups should be chosen over raw scores. However, the SSET demonstrated moderate internal consistency. Future studies should clarify whether the reliability of the SSET can be increased.

The Social Odor Scale (SOS) is a 12-item questionnaire initially developed and validated in Italian and German to investigate self-reported awareness of social odors, which are odors emanating from the human body that convey diverse information and evoke various emotional responses. The scale includes a total score and 3 subscales representing social odors in the respective categories: romantic partner, familiar, and strangers. Here, we aimed to (i) replicate the validation of the Italian and German versions of the SOS, (ii) translate and validate the SOS into multiple additional languages (French, English, Dutch, Swedish, Chinese), and (iii) explore whether the factor structure of each translated version aligns with the original versions. Confirmatory Factor Analysis (CFA) supported the scale's structure, yielding a good fit across all languages. Notable differences in SOS mean scores were observed among the different languages: Swedish participants exhibited lower social odor awareness compared to the other groups, whereas Chinese participants reported higher social odor awareness compared to Dutch and Swedish participants. Furthermore, SOS scores correlated with respondents' geographical location, with higher (i.e. northern) latitudes linked to lower social odor awareness. These results corroborate the SOS as a valid and reliable instrument, especially for the SOS total score and the Familiar and Partner factors, emphasizing the influence of individual and geographic factors on social odor awareness.