Chemosensory Tests Research Articles

Interpopulational Variations in Sexual Chemical Signals of Iberian Wall Lizards May Allow Maximizing Signal Efficiency under Different Climatic Conditions.

Sexual signals used in intraspecific communication are expected to evolve to maximize efficacy under a given climatic condition. Thus, chemical secretions of lizards might evolve in the evolutionary time to ensure that signals are perfectly tuned to local humidity and temperature conditions affecting their volatility and therefore their persistence and transmission through the environment. We tested experimentally whether interpopulational altitudinal differences in chemical composition of femoral gland secretions of male Iberian wall lizards (Podarcis hispanicus) have evolved to maximize efficacy of chemical signals in different environmental conditions. Chemical analyses first showed that the characteristics of chemical signals of male lizards differed between two populations inhabiting environments with different climatic conditions in spite of the fact that these two populations are closely related genetically. We also examined experimentally whether the temporal attenuation of the chemical stimuli depended on simulated climatic conditions. Thus, we used tongue-flick essays to test whether female lizards were able to detect male scent marks maintained under different conditions of temperature and humidity by chemosensory cues alone. Chemosensory tests showed that chemical signals of males had a lower efficacy (i.e. detectability and persistence) when temperature and dryness increase, but that these effects were more detrimental for signals of the highest elevation population, which occupies naturally colder and more humid environments. We suggest that the abiotic environment may cause a selective pressure on the form and expression of sexual chemical signals. Therefore, interpopulational differences in chemical profiles of femoral secretions of male P. hispanicus lizards may reflect adaptation to maximize the efficacy of the chemical signal in different climates.

Influenza Vaccinations and Chemosensory Function

Although influenza vaccines have saved millions of lives, some have been associated with extremely rare adverse effects such as Guillain-Barré syndrome, Bell's palsy, and optic neuritis. Despite the fact that olfactory loss after an influenza vaccination is noted in one case report, no quantitative olfactory testing was performed. Hence, it is unclear whether, in fact, olfactory dysfunction can be associated with such vaccinations. This study was designed to (1) identify patients from the University of Pennsylvania Smell and Taste Center who attributed their empirically determined chemosensory disturbances to influenza vaccinations and (2) determine whether influenza vaccinations add to the degree of olfactory or gustatory dysfunction due to other causes. A retrospective analysis of self-reported etiologies of 4554 consecutive patients presenting to the University of Pennsylvania Smell and Taste Center with complaints of chemosensory dysfunction was performed. Those who reported dysfunction secondary to influenza vaccinations were identified. Additionally, in a subset of 925 patients for whom detailed inoculation histories were available, it was determined whether the number of lifetime inoculations added to the deficits due to other causes. Nine of the 4554 patients (0.19%) attributed olfactory disturbances to an influenza vaccination. None complained of taste dysfunction. All nine had abnormally low scores on the University of Pennsylvania Smell Identification Test (p < 0.001), with three being anosmic and six microsmic. Seven had elevated phenyl ethyl alcohol detection thresholds (p < 0.05). Two cases exhibited mild-to-moderate loss of whole mouth taste function. Of the 925 patients, no association was evident between the number of lifetime vaccinations and the chemosensory test scores. In accord with previous studies, age and sex were significantly related to the test scores. A very small percentage of the 4554 patients evaluated (0.19%) attributed their chemosensory dysfunction to a prior influenza vaccination. No influences of the number of lifetime influenza vaccinations on the test scores were evident in the subset of 925 patients whose dysfunction was due to other causes.

Dysfunctional Chemosensation in Myasthenia Gravis

Myasthenia gravis has traditionally been viewed as a disorder that solely affects the neuromuscular junction within the peripheral nervous system. However, there is now evidence that the cholinergic dysfunction of this disorder may be more widespread than previously believed. This article provides a systematic review of the studies that examined smell and taste function in myasthenia gravis. We analyzed studies that reported chemosensory function alterations in patients with myasthenia gravis. PubMed, MEDLINE, Web of Science, EMBASE, and SciELO, searched to identify articles published from January 1950 through December 2012, were supplemented by relevant articles. The following information was identified from each article: the number of patients, number of controls (if any), clinical stage of patients, neurological involvement, serological state, taste or smell involvement, chemosensory test used, and country of publication. Ten studies reporting smell and taste function and dysfunction in patients with myasthenia gravis were identified, most of which were case reports commenting on apparent abnormalities in the taste system. The sole empirical study that investigated taste function, however, was negative, suggesting that some reports of taste loss may reflect olfactory loss. One study clearly documented olfactory dysfunction in patients with myasthenia gravis, dysfunction most likely attributable to altered central nervous system cholinergic function. Chemosensory dysfunction has been reported in a number of patients with myasthenia gravis. Given the close association between complaints of taste dysfunction and loss of flavor sensations secondary to olfactory system damage, quantitative testing should be used to accurately assess the nature and degree of the dysfunction present in this debilitating disorder.

Correlates of chemosensory malingering

Smell and taste tests are commonly employed to quantify chemosensory sequelae of head trauma, toxic exposures, and iatrogenesis. Malingering on forced-choice chemosensory tests can be detected by improbable responding. This study determined whether chemosensory test malingerers differ from nonmalingerers in terms of age, sex, education, and a range of self-reported behaviors and symptoms, potentially providing information of value for malingering detection. Case control. Twenty-two chemosensory malingerers were identified from a large clinical database and matched, randomly, to 66 nonmalingerers on the basis of etiology. Differences in demographics and responses to intake questionnaire items were statistically assessed. Logistic regression was used to identify variables that best predicted malingering behavior. Relative to nonmalingerers, malingerers reported significantly fewer allergies, dental problems, cigarettes smoked, surgical operations, nasal sinus problems, and use of medications, and significantly more putative symptom-related psychological duress, interference with daily activities, weight loss, decreased appetite, and taste loss. Litigation involvement was higher in malingerers than nonmalingerers. Age, sex, education, and length of symptom descriptions did not differentiate malingerers from nonmalingerers. Malingerers of chemosensory tests exaggerate symptom severity and underreport factors that might be construed as contributing to their dysfunction, such as smoking behavior, medication use, and general health. This contrasts with the behavior of malingerers of psychiatric symptoms, who typically exaggerate their general health problems. These data suggest that careful review of past medical records should be used to verify patient reports to better detect chemosensory malingering in cases where financial or other external incentives are present.

Perception of chemosensory stimuli and related responses to flavored yogurts in the young and elderly

This study examined the effects of chemosensory performance of two age groups on ratings of the just-right intensity of odor, flavor and coolness. Two experiments were conducted: (1) creation of a sensory profile by a trained panel and (2) hedonic testing of the yogurt samples by young ( n=47, 20–35 years) and elderly ( n=45, 65–82 years) subjects, who also participated in tests measuring their chemosensory performance. Eight yogurt samples (2×2×2 factorial design) were flavored with 6 or 10% sucrose, 0.2 or 0.8% lemon aroma and 0.004 or 0.012% menthol. Young subjects outperformed elderly in the olfactory, gustatory and trigeminal perception tests. Their performance in the chemosensory tests affected hedonic ratings of yogurts, especially in the case of the elderly. Among the elderly, just-right flavor was affected by the performance in olfactory, gustatory (sweet, sour) and trigeminal (menthol) tests. Just-right coolness was affected by olfactory perception and by identification of sweet taste. Pleasantness was affected by olfactory and menthol perception. Thus, stimulus-specific losses in chemosensory acuity of the elderly may lead to distorted perception of foods.

Special characteristics of expert assessment of olfactory and taste disorders

The number of medical expert opinions dealing with smell and taste disorders has continuously increased in recent years. However, an overview of the specific problems and results of those expert opinions has not been published until now. Olfaction was assessed by multiple subjective tests in 145 individuals with chemosensory dysfunction caused by trauma or occupational and environmental exposures. Additionally, a gustatory test, nasal endoscopy, anterior rhinomanometry, and radiography of the paranasal sinuses were performed. Malignering was diagnosed on a trial of multiple symptoms. Retronasal olfaction was tested using the Güttich gustatory olfaction test. Most of the medical expert opinions have been ordered by professional associations (42%) and insurance companies (28%). Compensation for olfactory dysfunction was claimed after trauma (64%), occupational exposure (23%) rhinosurgical procedures (8%), and laryngectomy (5%). Anosmia or hyposmia was claimed by 66% and 24% of all individuals, respectively. According to the results of the chemosensory tests, 41% of patients suffered from anosmia and 40% had hyposmia. Malignering was registered in 14%. The study shows that the "characteristic case" is a male in the late fourties, complaining of anosmia initially noticed after an occipital or frontobasal head trauma. The assessment of olfactory deficits related to toxic or chemical occupational exposure is difficult when a latency between the occupational exposure and the onset of chemosensory dysfunction is present. Moreover, interactions between the occupational exposure and nicotine or alcohol abuse must be taken into consideration. Claims for medical liability arose in 3% of the study group after septoplasty and sinus surgery.

Workshop on Taste and Smell in the Elderly: An Overview

The purpose of the workshop entitled Taste and Smell in the Elderly: Behavioral and Nutritional Consequences was 1) to review the current state of knowledge in the area of taste and smell, with emphasis on age-related changes, 2) to identify existing gaps in our knowledge, and 3) to develop future research strategies. There was general agreement that the majority of scientific studies have found impairments in taste and smell acuity in the elderly. These losses may result from normal aging, certain disease states especially Alzheimer’s disease, medications, surgical interventions, and environmental exposure. However, there are gaps in our knowledge of the basic mechanisms by which aging and environmental factors may impair the chemical senses in the elderly. Further research is also required in a variety of areas including chemosensory test procedures, food intake, and nutrition to understand fully the impact of chemosensory dysfunction on older individuals.

Taste and smell losses in HIV infected patients

Human immunodeficiency virus (HIV-1) associated wasting is an increasingly common clinical manifestation of AIDS. The pathogenesis of wasting is multifactorial and includes reduced caloric intake as a major contributing mechanism. The perceptions of taste and smell play an important role in stimulating caloric intake and in optimizing nutrient absorption through cephalic phase reflexes. The purpose of this study was to evaluate the degree of losses in taste and smell function that occur in subjects infected with HIV. Taste and smell function was evaluated in 40 HIV infected individuals and 40 healthy control subjects matched for age, sex, race, smoking behavior, and number of years of education. Chemosensory tests administered to subjects included taste and smell detection thresholds, taste and smell memory tests, taste and smell discrimination tests, and taste and smell identification tasks. Significant differences were observed between experimental and control subjects in glutamic acid taste detection threshold ( p < 0.001), quinine hydrochloride taste detection threshold (p < 0.001), menthol smell detection threshold ( p < 0.001) and in the taste identification task ( p = 0.006). Overall the results suggest abnormalities in the peripheral and central nervous systems, and subjective distortion of taste and smell. A significant correlation was not established between CDC classification of HIV infection and taste and smell function, although trends were observed suggesting worsening function with progression of HIV disease. These results document significant taste and smell losses in HIV infected subjects which may be of clinical significance in the development or progression of HIV associated wasting.

Congenital responsiveness of garter snakes to a dangerous prey abolished by learning

In nature, two garter snakes (Thamnophis melanogasterandT.eques) feed on the carrion-eating leechErpobdella punctatabut not on the blood-sucking leechHaementeria officinalis. In the laboratory, although ingestively naive snakes attacked both leeches, onlyE.punctatawas successfully ingested.Haementeria officinalisusually thwarted ingestion or killed the snake. In tests with leech odours, ingestively naiveT.melanogastershowed significant responsiveness only toE.punctata; but in tests with pieces of integument and live leeches, they responded positively to both leeches, responding more strongly toE.punctatthan toH.officinalis. Ingestive and chemosensory responses of litters ofT.melanogasterto the two leeches were correlated, implying possible genetic correlation. In a series of 15 trials with live leeches, snakes presented withH.officinalisprogressively ceased to attack, whereas snakes presented withE.punctatacontinued to attack. Snakes that alternately encounteredH.officinalisandE.punctataceased attackingH.officinalisand continued attackingE.punctata. In a subsequent chemosensory test based on tongue-flicking these snakes showed enhanced discrimination of the two leeches, suggesting that snakes can learn to rejectH.officinalis, a dangerous and probably unprofitable prey, using chemical cues.

Chemosensory responses of ciliates: A sensitive end point in xenobiotic hazard assessment

AbstractIt is known that ciliates exhibit chemosensory behavior. An assay implementing this response was performed with Tetrahymena thermophila, a well‐studied representative of the ciliates. A concentration‐dependent avoiding reaction was observed for all substances of the test battery, comprising a heterogeneous set of 43 compounds from the European Inventory of Existing Chemicals. Comparisons were made between toxic data from this chemosensory test and chemical concentrations leading to effects on Tetrahymena growth, and EC values from recommended aquatic toxicity tests. Low correlation coefficients indicate that the chemosensory response reflects chemical interactions, which cannot be adequately explained by these other tests. The chemosensory assay proved to be more sensitive in the majority of cases than the Tetrahymena growth test and standard tests with fish and Daphnia. Tetrahymena is able to recognize and avoid about half the substances at concentrations lower than those effective in the algae growth inhibition test. The behavioral response of Tetrahymena could provide further lexicological information and serve as a complementary sublethal end point for ecotoxicological screening purposes. © 1994 by John Wiley &amp; Sons, Inc..

Chemoinvestigatory and sexual behavior of male guinea pigs following vomeronasal organ removal

The vomeronasal organs of male guinea pigs were removed (VNX; n=10) or males experienced sham surgery (Sham; n=10). Subsequently a battery of chemosensory tests of investigatory responsiveness to conspecific urine was conducted. Additionally, male subjects were paired with female conspecifics for short and long periods and social and sexual behaviors were monitored. VNX males exhibited a depression in urine investigation and this depression became more profound following repeated testing and/or the passage of time. By 6.3 months following surgery, investigatory responsiveness to urine was practically eliminated. Maintenance of responsiveness to urine odors may require reinforcing input through the accessory olfactory system. In contrast to these effects on responsiveness to odors, VNX and Sham males were indistinguishable in their social and sexual behavior. These data indicate that male guinea pigs without a VNO: (1) Exhibit a depression of investigation of urine odors which is time dependent and which may involve an extinction-like process; (2) continue to discriminate classes of urine (e.g., urine from male vs urine from female conspecifics); and (3) exhibit normal sexual behavior. The vomeronasal organ in the male domestic guinea pig is apparently critical for the maintenance of normal responsiveness to sex odors but, in its absence, other sensory systems are capable of maintaining normal sexual behavior under conditions of laboratory testing.