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PubMedDate not supplied

Olfaction and multiple chemical sensitivity.

In this paper, a description of olfactory anatomy is presented, followed by a brief review of modern procedures for testing olfactory function. Information from the sole study which has quantitatively examined olfactory function in patients with apparent multiple chemical sensitivity (MCS) is presented. In essence, this study suggests that MCS is associated with increased nasal airflow resistance, respiration rate, heart rate, and scores on the Beck Depression Inventory, but not with significant changes in odor detection threshold sensitivity to phenyl ethyl alcohol and methyl ethyl ketone, the two target stimuli evaluated. Whether MCS patients evidence hypersensitivity to other chemicals is unknown.

Butanones↗
PubMed1994

Olfaction and endoscopic sinus surgery.

Recent advances in endoscopic evaluation of the nose and paranasal sinuses and endoscopic sinus surgery, coupled with the development of standardized testing of olfactory acuity, have permitted improved correction of olfactory dysfunction. Conversely, increase in the number of operations performed has increased the number of injuries to the olfactory pathways. The mechanisms of loss and potential preventive and corrective measures are reviewed with a goal to minimize the numbers of these complications.

Endoscopy↗
PubMed1993

Molecular genetics of Drosophila olfaction.

The functional organization of the Drosophila olfactory system has been studied using two complementary approaches. (1) A genetic screen has yielded olfactory mutants, of which one, acj6, shows greatly reduced electrical responses of its olfactory organs to all odorants tested except benzaldehyde (odour of almond). This mutant is also defective in olfactory behaviour at the larval stage. It is normal in tests of visual system physiology and behaviour. We aim to determine whether the acj6 gene is expressed on a fraction of the antennal surface. (2) We have carried out an enhancer trap screen for olfactory genes which are expressed on regions of the antennal surface. From a screen of 6400 enhancer trap lines, 12 show expression of a lacZ reporter gene in both larval and adult olfactory organs, but relatively little expression elsewhere. Most lines identify regions of the adult antenna and some show labelling of very small numbers of cells. One line shows sexual dimorphism in its expression pattern and another pattern becomes increasingly restricted with adult age. Several lines also show staining of other chemosensory organs and one also shows staining in the male reproductive tract. We have generated deletions of DNA flanking these enhancer trap insertions to determine whether any of the lines define genes associated with responses to specific sets of odorants.

Animals↗
PubMed1993

Molecular neurobiology of olfaction.

Odor discrimination is mediated via dendritic cilia of olfactory receptor neurons. Odorants traverse the aqueous mucous interphase that lines the surface of the olfactory neuroepithelium and interact with odorant receptors, which are members of the superfamily of G-protein-linked receptors. These interactions trigger synthesis of second messengers, including cyclic AMP and inositol triphosphate. Cyclic AMP opens a cation channel to elicit the generator current, which depolarizes the cell and, ultimately, leads to action potentials. Inositol triphosphate opens a calcium channel in the ciliary plasma membrane. Calcium entering through both this channel and the cyclic nucleotide-gated channel modulates the response to odorants by amplifying the generation of cyclic AMP after binding to calmodulin. Calcium also is essential for desensitization of olfactory receptor neurons. Differential expression of odorant receptors of diverse ligand specificities by different olfactory neurons ensures that the structures and concentrations of odorants that reach the chemosensory surface are encoded as distinct patterns of neuronal activity, which are relayed to the brain where they take shape as characteristic odor sensations.

Adaptation, Physiological↗
PubMed1977

Olfaction.

Explore the source record for details and available documents.

Humans↗
PubMed1977

Mutual action of taste and olfaction.

Subjects estimated the intensity of various concentrations of an odorant (ethyl butyrate), a tastant (sodium saccharin), and mixtures of the two. The question of primary interest was whether the perceived intensity of the odor-tast mixtures would be equal to, greater than , or less than the intensities of the unmixed components. The outcome approximated simple additivity: The intensity of the mixtures was only slightly less than the sum of the perceived intensities of the unmixed components. An examination of how subjects apportioned their judgments into the categories odor and taste revealed the existence of taste-smell confusions. Subjects ascribed little odor magnitude to solutions containing only sodium saccharin, but ascribed considerable taste magnitude to solutions containing only ethyl butyrate. The taste ascribed to ethyl butyrate was not due exclusively to its action on gustation since, when the nostrils were closed, as much as 80% of the "taste" disappeared. Subjects seem to resolve ambiguity regarding the locus of mutual olfactory-taste stimulation in favor of taste.

Butyrates↗
PubMed1977

The pleasantness of mixtures in taste and olfaction.

Human subjects rated the perceived intensity and pleasantness of taste mixtures (sucrose-quinine) and odor mixtures (lemon-heptanal or pyridine-lavender). The components of the mixture were judged as less intense when mixed than when judged alone. A multiple regression indicated that the pleasantness of a mixture can be predicted from a weighted additive function of the pleasantness values of the component sensations. Pleasantness values of the componetns had to be estimated from their pleasantness-intensity functions, because the perceived intensities of the components change when the components are combined. Weighting coefficients for the linear regressions were greater for the unpleasant components, especially in the odor mixtures.

Adult↗
PubMed2000

Olfactory deficits in patients with mild cognitive impairment predict Alzheimer's disease at follow-up.

OBJECTIVE: This study evaluated the predictive utility of olfactory identification deficits in patients with mild cognitive impairment for follow-up diagnosis of probable Alzheimer's disease. METHOD: Ninety outpatients with mild cognitive impairment were examined at 6-month intervals. Matched healthy comparison subjects (N=45) were examined annually. The University of Pennsylvania Smell Identification Test was given at baseline. RESULTS: Olfaction scores were lower in patients with mild cognitive impairment than in healthy comparison subjects. Seventy-seven patients were followed up; 19 were diagnosed with Alzheimer's disease by 2 years. Patients with low olfaction scores (< or =34 of 40), and patients with low olfaction scores who reported no subjective problems smelling, were more likely to develop Alzheimer's disease than other patients. In a Cox proportional hazards model adjusted for age, sex, modified Mini-Mental State score, and education, low olfaction scores did not predict time until development of Alzheimer's disease, but low olfaction scores accompanied by lack of awareness of olfactory deficits predicted time to development of Alzheimer's disease. This effect remained when attention or memory measures replaced modified Mini-Mental State score in the model. In patients with high Mini-Mental State scores (> or =27 of 30), low olfaction with lack of awareness remained a significant predictor of Alzheimer's disease. Olfaction scores of 30-35 showed moderate to strong sensitivity and specificity for diagnosis of Alzheimer's disease at follow-up. CONCLUSIONS: In patients with mild cognitive impairment, olfactory identification deficits, particularly with lack of awareness of olfactory deficits, may have clinical utility as an early diagnostic marker for Alzheimer's disease.

Aged↗
PubMed1997

Olfactory acuity as a function of age and gender: a comparison of African and American samples.

A frequently reported finding in age-related sensory impairment is that olfaction shows consistent and uniform decline with age. In most studies, discerning whether loss in olfaction is due to aging per se or to factors extrinsic to the aging process (e.g., smoking, chemical exposure, head injury) is difficult. Moreover, studies of olfaction have generally relied on data collected from samples drawn primarily from Western societies. As such, little is known regarding differences in olfaction involving non-Western cultures. Using international data from the 1986 National Geographic Smell Survey, responses of 19,219 American respondents and 3,204 respondents from Africa were analyzed. All respondents were screened for factors negatively affecting olfaction. Measures of olfactory acuity included odor detection, identification, intensity, and quality. The odor of interest was androstenone, a scent produced by bacteria on the human body and appearing in sweat. The results indicate that some measures of olfactory acuity tend to decline across age groups, but that this decline is less marked than reported in previous studies. The most important finding is that loss of olfaction is not consistent or uniform between geographic regions of America or Africa, between male vs. female respondents, or among the four measures of olfactory acuity. African respondents (both men and women) had significantly higher percentages of detection than did American respondents, women generally reported higher levels of olfactory functioning than did men, and some measures of olfaction were stable across age groups, or were higher among older respondents (e.g., odor identification).

Adolescent↗
PubMed1981

[Preservation of the olfactory tract following surgery on anterior communicating artery aneurysm using bifrontal craniotomy, and its functional prognosis (author's transl)].

Based upon 110 cases of AComA aneurysm approached via bifrontal craniotomy, we discuss preservation of the olfactory tracts and the functional prognosis for olfaction. (1) It is possible to preserve the olfactory tracts bilaterally or unilaterally in over 80% of such cases. (2) With regard to the correlation between surgical findings and subjective sense of olfaction, it was found that 47% of the cases with bilateral preservation, 34% with unilateral preservation and 33% of the cases with bilateral olfactory tract damage reported normal olfaction. (3) Objective examination of olfaction by an otolaryngologist showed that 84% of the patients reporting normal olfaction indeed had normal olfaction, whereas 91% of those reporting no olfaction were anosmic.

Cerebral Arteries↗
PubMed2005

How do children with adenoid hypertrophy smell and taste? Clinical assessment of olfactory function pre- and post-adenoidectomy.

OBJECTIVE: To assess the ability to smell and appreciate food in children with adenoid hypertrophy pre and post-adenoidectomy. METHODS: A total of 35 children with adenoid hypertrophy admitted for adenoidectomy (aged 5-9.3 years, mean age 5.9 years) were tested preoperatively. In a follow up appointment 3 months postoperatively, 28 of them returned and were tested again. The control group consisted of 30 healthy children (aged 5-10.2 years, mean age 6.1 years). Orthonasal olfactory function was assessed psychophysically using "Sniffin sticks" 12 item odor identification test. Retronasal olfaction was assessed using a collection of 12 grocery available powders applied to the oral cavity. RESULTS: Both orthonasal and retronasal olfactory function of the study group preoperatively were significantly lower in comparison with the results of the control group (p<0.0001). The difference in retronasal olfaction between groups was significantly higher in comparison with the difference in orthonasal odor identification (p=0.048). There is a strong correlation between adenoid hypertrophy grade and retronasal testing results (t=-5.461, p<0.0001), but not with the orthonasal results (t=-1.677, p=0.9). Significant improvement of orthonasal and retronasal olfaction was observed in the follow-up appointment (p<0.0001). Relative increase postoperatively was higher for the retronasal olfaction compared to orthonasal olfaction (p=0.0029). CONCLUSIONS: Children with adenoid hypertrophy have a reduced ability to smell, with retronasal olfactory function being more affected. Surgery had a greater impact on retronasal olfaction.

Adenoidectomy↗