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[Acoustic and vestibular analysers in patients with mine explosion trauma].

The aim of the study was examination of the acoustic and vestibular functions in patients with mine explosion trauma. Acoustic and vestibular functions were studied in 27 patients (16 females and 11 males aged 19-66 years, mean age 37.2 +/- 4.12) admitted to the ENT clinic of Moscow city hospital N 1. All the patients had suffered from explosion in closed space. General clinical and complex otoneurological examinations were made including gustatory and olfactory investigations, studies of the facial skin sensitivity, nasal mucosa, corneal reflex, soft palate motility, audiometry and vestibulometry. The findings of the tests suggested the following conclusions: mine explosion damages hearing by impairment of both sound conduction (85.7%) and sound perception (61.2%), the latter suffering primarily at the cochlear level; damage to the cranial nerves V and XIII occurs at the level of the brain stem; mixed affection of the vestibular analyzer is seen primarily at the level of stem nuclei.

Adult↗

Impaired odor adaptation in olfactory receptor neurons after inhibition of Ca2+/calmodulin kinase II.

Odor adaptation in vertebrate olfactory receptor neurons (ORNs) is commonly attributed to feedback modulation caused by Ca(2+) entry through the transduction channels, but it remains unclear and controversial whether this Ca(2+)-mediated adaptation resides in the cAMP-gated channel alone or whether other molecules of the transduction cascade are modulated as well. Attenuation of adenylyl cyclase activity by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) has also been proposed as a mechanism for adaptation. To test this in intact ORNs, we have compared the properties of adaptation induced by a sustained (8 sec) or brief (100 msec) odor stimulus. Although adaptation induced by both types of stimuli occurs downstream from the odor receptors and is Ca(2+)-dependent, only adaptation induced by a sustained pulse involves alterations in the odor response kinetics, consistent with a reduction in the rate of adenylyl cyclase activation. By disrupting CaMKII to block adenylyl cyclase attenuation using a specific peptide inhibitor of CaMKII, autocamtide-2-related inhibitory peptide (AIP), we show that this reaction is necessary for odor adaptation in vivo. With CaMKII disrupted, adaptation induced by a sustained stimulus is significantly impaired: the onset rate of adaptation is decreased by threefold, and the recovery rate from adaptation is increased by up to sixfold. In contrast, adaptation induced by a brief odor pulse is unaffected, demonstrating that the effect of AIP must be highly specific. The results indicate that CaMKII controls the temporal response properties of ORNs during odor adaptation. We propose that CaMKII plays a prominent role in odor perception.

Adaptation, Physiological↗

[The power of odors--pathogenic or unpleasant].

Modern toxicological studies have prompted us to rethink the role of olfaction and odours in our world. Our sense of smell is able to discriminate between an almost unlimited number of compounds of different chemical composition at extremely low threshold levels. Olfaction is classified as a chemical sense because of the bimolecular excitation process between the stimulant and receptor molecule. Receptor molecules of the olfactory epithelium have a variable region of the molecule which can differentiate between an unlimited number of aromatics. The sense of smell--the oldest phylogenetic sense--is therefore in very intensive contact with the "chemical" environment. Virtually all of the aromatic products which we are exposed to are highly complex chemical mixtures of numerous individual components which have a toxic potential little investigated to date. The perception of odours can be interpreted as a warning--a protective mechanism necessary for survival. At the same time, however, the exaggerated use of perfumes is held to be indicative of a highly cultured status. Unlike any other sense, that of smell is directly connected to archaic areas of the paleocortex region of the cerebral hemisphere, so that an odour will fill us with joy or abhorrence outside of our control. Odours cannot, therefore, be analyzed rationally without eliciting instinctive reactions, positive or negative, which result in acceptance or rejection. The highly developed memory for odour types is believed to be coupled to the route of the olfactory tract. The use of olfactometry today enables odours to be reliably quantified and characterized in a reproducible manner.

Humans↗

Ontogenesis of the functional activity of guinea-pig olfactory bulb: autoradiographic study with the 2-deoxyglucose method.

An ontogenetic study of [14C]2-deoxyglucose (2-DG) uptake within the olfactory bulbs was performed in 1-, 4-, 7- and 21 day-old guinea-pigs exposed to a pure chemical odor, ethyl acetoacetate (EAA). Whatever the age studied, the patterns of glomerular activity are characterized by restricted spots which extend along the bulb, and by sheets of increased density overlapping 10-30 contiguous glomeruli, found only on the lateral aspect of the bulb. Even if the main features of the 2-DG patterns related to EAA are already present at birth, a perceptible evolution of these patterns is observed during the first 3 postnatal weeks. The changes include on the one hand, an increase of the spot-like glomerular labeling which appears particularly prominently on the medial and dorsal aspects. On the other hand, whereas the restricted spots overlaying 1-3 glomeruli become more numerous with age, a decrease in size and in extension of the sheet-like glomerular activity is noted. The results confirm the high maturation level of the olfactory bulbs in newborn guinea-pigs. Some implications related to the mainly prenatal maturation of the olfactory system are discussed.

Animals↗

Olfactory sensitivity in medical laboratory workers occupationally exposed to organic solvent mixtures.

BACKGROUND: Published epidemiological information relating the effects of occupational exposure to organic solvents (OS) to olfaction is limited. AIMS: The objectives of this pilot study were to measure the chemosensory abilities of medical laboratory employees occupationally exposed to OS mixtures, to compare these with control workers employed within the same occupational setting and to correlate chemosensory performance with OS exposure history and with employees' hedonic (pleasantness) perceptions about workplace OS odors. METHODS: Twenty-four medical laboratory employees (OS-exposed technicians plus control workers minimally exposed to OS) completed a health-related questionnaire, a test of pyridine odor detection threshold, along with a gustatory detection threshold test involving aqueous quinine solutions. Estimates of cumulative hours of OS exposure (CSI) were calculated from self-reports. RESULTS: OS-exposed laboratory technicians detected weaker concentrations of pyridine odor. Positive correlations were detected between CSI estimates to both pyridine detection and the degree that participants reported that OS odors were present in the workplace. However, no association was detected between pyridine detection and how unpleasant workplace OS odors were perceived. The OS-exposed participants were able to detect weaker concentrations of quinine. Compared to controls, OS-exposed workers complained more of experiencing several symptoms while working, including headaches, nasal irritation and mild cognitive impairment. CONCLUSIONS: The results of this cross-sectional pilot study indicated that, compared to controls, medical laboratory technicians exposed to low-level OS mixtures displayed evidence of elevated olfactory sensitivity (hyperosmia) to pyridine odor. The relation of this study's results to chemical intolerance warrants further investigation.

Adult↗

Tonkean macaques ( Macaca tonkeana) find food sources from cues conveyed by group-mates.

It is possible that non-specialised cues transmitted by conspecifics guide animals' food search provided they have the cognitive abilities needed to read these cues. Macaques often check the mouth of their group-mates by olfactory and/or visual inspection. We investigated whether Tonkean macaques ( Macaca tonkeana) can find the location of distant food on the basis of cues conveyed by group-mates. The subjects of the study were two 6-year-old males, who belonged to a social group of Tonkean macaques raised in semi-free-ranging conditions. In a first experiment, we tested whether the subject can choose between two sites after having sniffed a partner who has just eaten food corresponding to one of the sites. We found that both subjects were able to choose the matching site significantly above the chance level. This demonstrated that Tonkean macaques are capable of delayed olfactory matching. They could associate a food location with an odour conveyed by a partner. In a second experiment, the same subjects were allowed to see their partner through a Plexiglas window. Both subjects were still able to choose the matching site, demonstrating they could rely on visual cues alone. Passive recruitment of partners appears possible in macaques. They can improve their foraging performances by finding the location of environmental resources from olfactory or visual cues conveyed by group-mates.

Animal Communication↗

Loss of olfactory receptor genes coincides with the acquisition of full trichromatic vision in primates.

Olfactory receptor (OR) genes constitute the molecular basis for the sense of smell and are encoded by the largest gene family in mammalian genomes. Previous studies suggested that the proportion of pseudogenes in the OR gene family is significantly larger in humans than in other apes and significantly larger in apes than in the mouse. To investigate the process of degeneration of the olfactory repertoire in primates, we estimated the proportion of OR pseudogenes in 19 primate species by surveying randomly chosen subsets of 100 OR genes from each species. We find that apes, Old World monkeys and one New World monkey, the howler monkey, have a significantly higher proportion of OR pseudogenes than do other New World monkeys or the lemur (a prosimian). Strikingly, the howler monkey is also the only New World monkey to possess full trichromatic vision, along with Old World monkeys and apes. Our findings suggest that the deterioration of the olfactory repertoire occurred concomitant with the acquisition of full trichromatic color vision in primates.

Alouatta↗

Vanilloid (capsaicin) receptors in health and disease.

The cloned vanilloid (capsaicin) receptor subtype 1 (VR1) integrates multiple noxious stimuli on peripheral terminals of primary sensory neurons. The initial excitation of these neurons is followed by a lasting refractory state, traditionally termed desensitization, that has clear therapeutic potential. Capsaicin is used to relieve neuropathic pain, uremic pruritus, and bladder overactivity. The ultrapotent vanilloid resiniferatoxin, now in phase 2 clinical trials, has improved tolerability. A less recognized human exposure to high capsaicin concentrations may occur by pepper sprays used in law enforcement. Evidence is mounting that VR1 expression is not restricted to sensory neurons. From the olfactory bulb to the cerebellum, VR1-expressing neurons are present in a number of brain nuclei, where they might be activated by anandamide. VR1 presence also was demonstrated in nonneuronal tissues. These discoveries place VR1 in a much broader perspective than pain perception and enhance the potential for unforeseen side effects, especially following prolonged vanilloid therapy. The expression of VR1 is plastic and down-regulated during vanilloid therapy, which might have a pivotal role in desensitization. Good evidence suggests altered VR1 expression in various disease states. This recognition not only may provide novel insights into pathogenesis but also may prove useful in diagnosis.

Animals↗

A study of behavioral and sensorial bases of radial maze learning in mice.

In order to analyze the various sensorial and behavioral modes implied in learning on a radial maze, three isogenic mice groups (BALB/C, C57BL/6, and CB6F1) were subjected to four different learning procedures, each ending with a probe test. These four procedures examined the use of radial strategies and allowed to dissociate the use of olfactory and spatial cues. Results showed that all mice preferred to use a radial strategy. When the confinement procedure rendered the use of a radial strategy impossible, BALB/C mice were incapable of establishing spatial orientation but were able to learn the task by using olfactory cues. C57BL/6 mice, on the other hand, seemed to use spatial cues exclusively, while the CB6F1 hybrids showed a high degree of plasticity, using either type of information. These strain-specific differences point out the heterogeneity of the processes called into play during radial maze learning and show that unless olfactory cues are carefully controlled they can account for choice accuracy in some mice.

Animals↗

Hallucinations in Kenyan schizophrenic patients.

Eighty Kenyan 'psychotic' patients were screened using the New Haven Schizophrenic Index (NHSI) and were all studied for hallucinations using standardised definitions. Fifty-one of the patients were NHSI positive and the rest NHSI negative. Sixty-one percent of the NHSI positive had hallucinations in one or more modalities as compared with 31% of the NHSI negative group. Of the NHSI positive 51% had auditory hallucinations directly to the patient, 43% had visual hallucinations and 25% had olfactory hallucinations. These results are compared and contrasted with the very few similar observations made elsewhere.

Adolescent↗

An ecological approach to mechanisms determining individual differences in perception.

In 1982 Satow proposed four hypothetical properties determining mechanisms of individual differences in perceptions; these were supported by results of a factor analysis of responses to a 58-item check list. Present work confirmed the four properties (intense sensitivity, temporal sensitivity, sensory-motor reactivity, and possible range of total stimuli), and obtained a property, preference for intense and prolonged stimuli, from a principal component analysis of data from a 60-item list given to 316 subjects. The 60-item list is a revised version of the 58-item list which asked subjects about their subjective sensitiveness and preferences for environmental sensory stimuli (visual, auditory, olfactory, and tactile). Within subjects relationships among these properties are interindependent, since for individuals correlations of factor-score estimates between pairs of these properties were near zero. This interindepedence supported a model of four hypothetical types of individuals, explaining the individual differences on the grounds of the relations among the properties.

Adult↗

Genetics of sensory nutrition.

Sensory nutrition is an emerging research area that examines how chemosensory perception, particularly taste and smell, shapes dietary behaviours, nutritional status, and disease risk. Variation in how individuals perceive the same foods may help explain differences in diet quality and responsiveness to behavioural dietary interventions, yet chemosensory phenotypes are rarely measured at the population level. Genetic variation contributes to this perceptual diversity and provides a framework for investigating sensory determinants of diet using genomic approaches. This review summarises evidence linking chemosensory genetics to perception and dietary behaviours, and discusses applications for causal inference and for precision and personalised nutrition. Twin studies reveal moderate to high heritability for bitter taste traits, with more modest and phenotype-dependent estimates for sweetness, sourness, saltiness, fat-related traits, and olfactory measures. Genome-wide association studies have identified loci in taste and olfactory receptor genes associated with specific chemosensory traits as well as liking and intake of various foods, although the evidence remains concentrated on bitter taste and populations of European ancestry. These genetic variants have been used in Mendelian randomisation, a genetics-based approach that strengthens causal inference, to test whether sensory traits influence dietary behaviour. For precision nutrition, evidence for taste genotype-stratified interventions remains limited and mixed. Realising the promise of sensory nutrition will require scalable and standardised chemosensory phenotyping, Findable, Accessible, Interoperable, and Reusable (FAIR) data infrastructure, expanded research in diverse populations, and integration with broader biological and sociocultural determinants of dietary intake.

Genetics↗

Perception of breath components by the tropical bont tick, Amblyomma variegatum Fabricius (Ixodidae). II. Sulfide-receptors.

Wall-pore sensilla in the capsule of Haller's organ on foreleg tarsi of the tick, Amblyomma variegatum, show multicellular responses upon stimulation with human and bovine breath. Filtering breath through charcoal removes the stimulant for some of these receptors. Analysis by gas chromatography coupled with olfactory sensillum electrophysiological recordings indicates that an ethanol extract of the breath components trapped on charcoal contains a major stimulant eluting at the same retention time as H2S. Two types of H2S-sensitive receptors have been identified. They are housed in separate sensilla, and are called sulfide-receptor 1 and 2. Although, both receptor types are characterized by a high sensitivity to H2S with an estimated threshold of ca. 0.1 ppb and a response range covering 5-6 log orders of magnitude, their overall response to sulfides and mercaptans is nevertheless dissimilar. The type 1 receptor fires slightly more upon stimulations with H2S than type 2, whereas ethylmercaptan induces a stronger response from type 2, and dimethyl sulfide activates only receptor 2. In a bioassay, H2S tested at concentrations of ca. 0.02 ppm and 1 ppm equally arouses 60% of resting ticks. Two-thirds of these ticks quest the air with their first pair of legs, and the remainder start active search. By contrast, H2S at ca. 1 ppm in a mixture with CO2 severely diminishes the locomotor stimulating effect of CO2.

Animals↗

Adenylyl cyclase activity in turtle vomeronasal and olfactory epithelium.

Many vertebrates have two olfactory systems such as the main olfactory organ and the vomeronasal organ. To compare the transduction mechanism in both systems, we measured adenylyl cyclase activity in turtle vomeronasal and olfactory epithelium preparations. Whereas forskolin and GTP induced cAMP accumulation in vomeronasal preparations, common odorants, which induced cAMP accumulation in olfactory preparations and electrophysiological responses in vomeronasal organs, did not induce cAMP accumulation in vomeronasal preparations. The present results suggest that the cAMP-mediated transduction pathway in the vomeronasal organ is not involved in transduction for common odorants and probably plays a role in perception of specific chemosignals.

Adenylyl Cyclases↗

Color learning and memory in honey bees are not affected by protein synthesis inhibition.

The role of protein synthesis was tested for memory formation after color learning in honey bees. Free flying bees were trained to a feeding place. Before the color conditioning started, foragers accustomed to flying to the feeding place received an injection of either cycloheximide in bee ringer or bee ringer alone into the brain. Afterward, the animals were trained appetitively to a specific colored target by three training trials. During the test situation, two targets with different colors and no reward were presented. The choice behavior toward the two targets was evaluated. The first test immediately followed the last trial, the second test 24 h later. A comparison between cycloheximide- and ringer-injected bees showed no significant difference in choice behavior in either test. Although the injection of cycloheximide causes the inhibition of protein synthesis (> 95%) for a period of 3 h, the memory for the learned color signal is not affected. These results corroborate those found for the olfactory conditioning of the proboscis extension reflex in bees (Wittstock, Kaatz, & Menzel, 1993, Menzel, Gaio, Gerberding, Nemrava, & Wittstock, 1993).

Animals↗