Hydrophobic solution functions as a multifaceted mosquito repellent by enhancing chemical transfer, altering object tracking, and forming aversive memory.

Developing a safe and potent repellent of mosquitoes applicable to human skins is an effective measure against the spread of mosquito-borne diseases. Recently, we have identified that hydrophobic solutions such as low viscosity polydimethylsiloxane (L-PDMS) spread on a human skin prevent mosquitoes from staying on and biting it. This is likely due to the ability of L-PDMS in wetting mosquito legs and exerting a capillary force from which the mosquitoes attempt to escape. Here we show three additional functions of L-PDMS that can contribute to repel Aedes albopictus, by combining physicochemical analysis and behavioral assays in both an arm cage and a virtual flight arena. First, L-PDMS, when mixed with topical repellents and applied on a human skin, enhances the effect of topical repellents in reducing mosquito bites by efficiently transferring them to mosquito legs upon contact. Second, L-PDMS applied to mosquito tarsi compromises visual object tracking during flight, exerting an influence outlasting the contact. Finally, L-PDMS applied to mosquito tarsi acts as an aversive reinforcer in associative learning, making mosquitoes avoid the conditioned odor. These results uncover a multifaceted potential of L-PDMS in altering a sequence of mosquito behaviors from biting a human skin, visual object tracking following takeoff, to the response to an odor linked with L-PDMS.

Assessment of Multidimensional Health Care Parameters Among Adults in Japan for Developing a Virtual Human Generative Model: Protocol for a Cross-sectional Study.

BACKGROUND: Human health status can be measured on the basis of many different parameters. Statistical relationships among these different health parameters will enable several possible health care applications and an approximation of the current health status of individuals, which will allow for more personalized and preventive health care by informing the potential risks and developing personalized interventions. Furthermore, a better understanding of the modifiable risk factors related to lifestyle, diet, and physical activity will facilitate the design of optimal treatment approaches for individuals. OBJECTIVE: This study aims to provide a high-dimensional, cross-sectional data set of comprehensive health care information to construct a combined statistical model as a single joint probability distribution and enable further studies on individual relationships among the multidimensional data obtained. METHODS: In this cross-sectional observational study, data were collected from a population of 1000 adult men and women (aged ≥20 years) matching the age ratio of the typical adult Japanese population. Data include biochemical and metabolic profiles from blood, urine, saliva, and oral glucose tolerance tests; bacterial profiles from feces, facial skin, scalp skin, and saliva; messenger RNA, proteome, and metabolite analyses of facial and scalp skin surface lipids; lifestyle surveys and questionnaires; physical, motor, cognitive, and vascular function analyses; alopecia analysis; and comprehensive analyses of body odor components. Statistical analyses will be performed in 2 modes: one to train a joint probability distribution by combining a commercially available health care data set containing large amounts of relatively low-dimensional data with the cross-sectional data set described in this paper and another to individually investigate the relationships among the variables obtained in this study. RESULTS: Recruitment for this study started in October 2021 and ended in February 2022, with a total of 997 participants enrolled. The collected data will be used to build a joint probability distribution called a Virtual Human Generative Model. Both the model and the collected data are expected to provide information on the relationships between various health statuses. CONCLUSIONS: As different degrees of health status correlations are expected to differentially affect individual health status, this study will contribute to the development of empirically justified interventions based on the population. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/47024.

Dynamics of odorant binding to thin aqueous films of rat-OBP3.

Uptake, retention and release of 5 selected odorants (benzaldehyde, 2-methylpyrazine, 2-isobutyl-3-methoxypyrazine, 2-isobutylthiazole, and 2,4,5-trimethylthiazole) by recombinant rat odor-binding protein 3 (rat-OBP3) were measured in a model system under nonequilibrium conditions. Gaseous odorants were introduced into a 100 mm section of a polar deactivated capillary in which aqueous rat-OBP3 films were formed to mimic the olfactory epithelium (OE), and the change in the gas-phase concentration of the outflow gas was monitored in real time using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The 5 odorants were chosen because they exhibited a broad range of dissociation constants with rat-OBP3 and because they were amenable to detection by on-line APCI-MS. All 5 odorants were quantitatively bound by rat-OBP3, which resulted in an effective concentration of the odorants in the aqueous layer (about 50 000-fold). Odorant release from the rat-OBP3-odorant complex into the gas phase showed that odorant release was governed by the dissociation constant of the complex and the flow rate of odorant-free air. When 2 odorants were introduced into the system, odorant uptake and release were influenced by the method of introduction and their relative affinities for the protein. Because rat-OBP3 exhibits typical odorant-binding characteristics, the results not only provide fundamental information on the kinetics of odorant mass transfer induced by the presence of OBPs in the olfactory mucus layer but also support the possibility that vertebrate OBPs may facilitate the accumulation of odorants in the OE.

Identification of new odoriferous compounds in human axillary sweat.

3-Hydroxy-3-methylhexanoic acid (1) and the 3-sulfanylalkan-1-ols 2-5 were identified to contribute to the odor of human axillary sweat. Quantitative analyses of axillary sweat extracts from 50 healthy men showed an unambiguous correlation between the detected levels of 1 and the intensity of the axillary odor. Chiral-GC analyses revealed 1 to be a 72:28 mixture of the (S)/(R)-isomers. Optically pure (S)-1 (>97% ee) emanated a strong spicy note, which recalled typical axillary odors. 3-Methyl-3-sulfanylhexan-1-ol (2), the enantiomeric ratio of which equaled that of 1, was present in greater quantity than any of the other 3-sulfanylalkanols. Optically pure (S)-2 (>97% ee) had a strong meaty, fruity note, also reminiscent of axillary odor. The compounds identified, in particular (S)-1 and (S)-2, contribute significantly to the olfactory impression of human axillary odor.