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PubMed1993

Chemosensory function, food preferences and appetite in human liver disease.

We evaluated chemosensory function, food preferences, and appetite in 88 patients with liver disease including those with hepatitis, cirrhosis, primary biliary cirrhosis, and sclerosing cholangitis. Reported chemosensory disturbances were common in the patients with liver disease: over 40% reported recent taste changes, and 27% reported recent changes in smell, compared to only 6% of healthy, age- and gender-matched controls with no history of marked chemosensory malfunction. Compared to controls, a greater proportion of liver patients reported food cravings (47 vs. 17%) and food aversions (33 vs. 16%). Foods with a predominantly bitter taste were specifically less preferred in patients with liver disease compared to healthy controls. Patients were also more likely to report poor to fair appetite than controls (37 vs. 5%). Groups of patients with different types of liver pathology showed varying patterns of food preferences, suggesting that dietary recommendations to liver patients might be tailored to the altered preferences associated with a particular type of hepatic dysfunction.

Adult↗
PubMed2000

You can teach an old dog new tricks: olfaction and responses to novel foods by the elderly.

It can be difficult to document effects of age-related olfactory loss on eating behavior. However, we have reported that elders, especially those with poor olfaction, were more willing to accept novel foods than were younger adults. It was also found that elderly subjects were more willing to accept foods with unpleasant odors than were young subjects. Because there is often confounding between a food's odor pleasantness and its familiarity, the purpose of this study was to separate the effects of familiarity and odor pleasantness on food acceptance by the elderly. There was no evidence for effects of age or olfactory sensitivity on food neophobia. However, elderly subjects with poor olfaction showed less reluctance to try the unpleasantly smelling foods than did other subjects. These results suggest that increased willingness to try novel foods among elderly subjects with poor olfaction in earlier work was due to decreased rejection of foods with unpleasant odors and not due to decreased food neophobia per se.

Aged↗
PubMed2002

Maternal olfaction differentially modulates oxytocin and prolactin release during suckling in goats.

In postparturient goats, olfactory recognition of the young allows the establishment of a selective bond between the mother and her kids. Once this bond is formed, the mother rejects alien young that attempt to suckle. We tested whether the development of the maternal selective bond in goats modulates prolactin (PRL) and oxytocin (OT) release in response to suckling. On day 37 of lactation, serial blood samples were taken during nursing of the mother's own or alien kid(s) in 10 intact/selective goats and in 10 goats rendered anosmic/nonselective through prepartum peripheral ZnSO(4) irrigation. Spontaneous nursing behavior was also studied weekly from day 7 to 30 of lactation, at which time milk production was measured. Maternal selectivity had no effect on PRL release, in contrast to OT release, which was significantly affected by this factor. Intact mothers released OT only when nursing their own kids, but not with aliens, while anosmic/nonselective dams showed an increase in OT levels regardless of the identity of the kids. In addition to these effects on maternal selectivity, the amplitude of the response of both hormones was lower in anosmic mothers than in intact mothers. Finally, nursing behavior and milk production were not significantly affected by anosmia. We conclude that maternal selective behavior in goats, which relies on the individual olfactory signature of the kid, modulates the OT, but not the PRL, response to suckling. In addition, perception of the smell of the young appears to have a general facilitatory effect, independent of the kid's identity, on the release of both hormones.

Animals↗
PubMed1999

Interactions between perinatal and neonatal associative learning defined by contiguous olfactory and tactile stimulation.

Tactile stimulation of the neonate, as performed by the mother during and after delivery, has been described as an effective unconditioned stimulus during early ontogeny (Leon, 1987; Ronca & Alberts, 1994). The present experiments examined the interaction between perinatal and neonatal learning determined by the explicit association between alcohol odor and vigorous body stimulation of the perinatal organism. In Experiment 1, rat fetuses were exposed to either alcohol or saline 10 min prior to cesarean delivery. The alcohol administration procedure here employed was sufficient to provide sensory contamination of the amniotic fluid but avoid fetal alcohol intoxication. Pups in the two prenatal treatments later experienced the smell of alcohol, tactile stimulation, or both stimuli explicitly paired or unpaired. Other postnatal groups were composed of pups that had no explicit experience with either experimental stimulus. Pups subjected to alcohol odor in utero displayed more overall motor activity in response to that odor than saline controls. The increased motor responses were further potentiated in pups that experienced additional postnatal alcohol odor paired with tactile stimulation. In Experiment 2, pups were exposed to alcohol in the amniotic fluid 10 or 30 min prior to birth. As previously demonstrated the memory acquired in utero appears highly dependent upon contingency between exposure to this particular scent and delivery procedures. Pups in both prenatal treatment groups were then exposed to alcohol odor paired or unpaired with tactile stimulation. Some control animals received no further experience with either stimuli. Those pups exposed to alcohol odor paired with tactile stimulation both pre- and postnatally later showed maximum motor activity elicited by the odor of alcohol. The results support the notion of fetal associative learning comprising alcohol's chemosensory cues and behaviorally activating stimuli. Furthermore, the conditioned response under analysis is potentiated whenever neonates are reexposed to contingent presentations of the elements that defined the original associative memory.

Administration, Inhalation↗
PubMed1998

Controlled ethyl tert-butyl ether (ETBE) exposure of male volunteers. II. Acute effects.

The aim of this study was to evaluate acute effects of ethyl tert-butyl ether (ETBE) in man after short-term exposure. ETBE may in the future replace methyl tert-butyl ether, a widely used oxygenate in unleaded gasoline. Eight healthy male volunteers were exposed to ETBE vapor for 2 h at four levels (0, 5, 25, and 50 ppm) during light physical exercise. The subjects rated irritative symptoms, discomfort, and central nervous system effects in a questionnaire. Ocular (eye redness, tear film break-up time, conjunctival epithelial damage, and blinking frequency), nasal (acoustic rhinometry and analysis of inflammatory markers and cells in nasal lavage fluid), and pulmonary (peak expiratory flow, forced expiratory volume in 1 s, forced vital capacity, vital capacity, and transfer factor) measurements were performed. Significantly increased ratings of solvent smell (p = 0.001, repeated-measures ANOVA) were seen during exposures and correlated to exposure levels. Furthermore, significantly elevated ratings of discomfort in throat and airways were seen during and after 50 ppm compared to the control exposure (p = 0.02). Increased nasal swelling (p = 0.001) and blinking frequency (p = 0.01) were noted at all exposure levels, but their magnitudes were not related to exposure levels. A slightly impaired pulmonary function was seen at 25 and 50 ppm, since forced vital capacity (p = 0.02) and vital capacity (p = 0.04) differed significantly from the clean air exposure. Although the impairments seemed to fall within normal inter- and intraindividual variation and have no clinical relevance as such, it cannot be excluded that other individuals may react more severely than eight healthy male volunteers in this study.

Administration, Inhalation↗
PubMed1991

Conceptual approaches to avian navigation systems.

The general basis of migratory orientation in birds is most probably an endogenous time-and-direction programme. Directions are selected with respect to celestial as well as geomagnetic clues. These clues appear to be integrated within a system that profits from the special advantages of either kind of environmental signal, and thereby can cope with their limitations. Using these clues, and following a genetically determined intended direction (or sequence of directions) over a genetically determined period of time, a bird may reach a larger population-specific area. However, it will hardly be able to find a particular location, such as, for instance, its previous breeding site. Homing to a familiar site over several hundred kilometers of unfamiliar terrain is substantially based on the smelling of atmospheric trace compounds. At shorter distances from home, orientation by means of--presumably visual--familiar landmarks completes the repertoire of mechanisms guiding a bird back home. These mechanisms are considered to be based on different kinds of 'maps' and 'compasses'. Conceptual approaches to the properties of an 'olfactory map' have as yet only reached an early state of speculation.

Animals↗
PubMed1991

Reversible rat mesenteric mast cell swelling caused by vagal stimulation or sham-feeding.

Fragments of rat mesentery were examined using acetylthiocholine to detect cholinergic nerve fibers and toluidine blue to identify mast cells. 59.2 +/- 2.6 percent of mast cells were at less than one-half mean cell diameter (4-5 microns), from the nerve fibers. Under the electron microscope, the membrane of mast cells was within less than 50 nm from axon membranes, suggesting a synaptic type of connection. Average mast cell area in fasted rats increased following feeding, stimulation of the left abdominal vagus nerve or exposure of the animal to the smell of food. It returned to control values within 60-80 min. Granule exocytosis was not observed. Mast cell swelling was prevented by atropine and induced by intravenously administered carbamylcholine. It appears that in rat mesentery, impulses travelling via cholinergic, parasympathetic fibers innervating mast cells, cause mast cell swelling. Compound 48/80 administered to rats at doses causing little degranulation and minimum release of histamine, caused extensive, reversible swelling of mesentery mast cells.

Animals↗
PubMedDate not supplied

Trace elements in human parotid saliva.

Although various proteins and some electrolytes have been measured in human saliva, little systematic data about the major and minor elemental components of this body fluid have been obtained. In order to obtain such data, concentrations of C, Na, P, Cl, K, Ca, Sc, Cr, Fe, Co, Zn, Se, Br, Rb, Sb, I, and Cs in human parotid saliva were measured by instrumental nuclear methods. The data obtained confirmed the relative lack of Zn in saliva of patients with hypogeusia (decreased taste acuity) and suggested that concentrations of Na, Cl, Br, and Ca followed the order: normals greater than hypogeusia greater than hyposmia (decreased smell acuity). To compare concentrations of elements in saliva with those in blood and urine, absolute concentrations were normalized to that of Na through the use of a concept called an enrichment factor. On this basis, parotid saliva is relatively depleted in Se, Zn, and Fe and enriched for most other elements relative to blood plasma indicating that the fluid is not simply a transudate of blood plasma. Using this same technique, saliva composition was found more similar to urine than blood plasma, being relatively depleted in Se, Cs, and Co, being enriched in I, Br, and Cr and having about the same relative concentrations of P, Cl, Zn, Fe, Ca, K, and Rb. As the total body concentrations of many of the enriched elements in saliva are extremely small, their enrichment in saliva suggests special roles for these elements in the oral cavity. Because of its accessibility, ease of collection, and interaction with some body constituents, saliva represents a useful, albeit neglected, tool in the diagnosis of some physiological and pathological changes in body function and in understanding important aspects of trace metal metabolism.

Adult↗
PubMed2000

Bioconversion of lutein to products with aroma.

A residual mud sample from the marigold flower dehydration process was screened and 19 putative colonies were isolated for their ability to degrade lutein in a chemically defined medium supplemented with marigold flower flour as a carbon source. Among the colonies isolated, two generated volatile compounds in fermentation and one was chosen for further study for its ability to produce a strong tobacco smell. This colony contained two microorganisms, identified as Geotrichum sp. and Bacillus sp. The aroma production requires the presence of both microorganisms and lutein. Using gas chromatography coupled to mass spectrometry (GC/ MS), four compounds were identified: 7,8-dihydrobeta-ionol, beta-ionone, 7,8-dihydro-beta-ionone, and 3-hydroxy-beta-ionone, in proportions of 84.2%, 9.4%, 3.5%, and 2.9%, respectively.

Biodegradation, Environmental↗
PubMed2000

Sulphur-containing "perfumes" attract flower-visiting bats.

We tested the attractiveness of individual scent compounds of bat-pollinated flowers to their pollinators, small flower-visiting bats of the genus Glossophaga (Phyllostomidae). Twenty compounds belonging to four different chemical substance classes were tested, both in the laboratory and in the field. In the laboratory, the bats (Glossophaga soricina) approached odour sources spontaneously and without preceding experience. Without ever receiving any reward they preferred the scent of a sulphur-containing compound, dimethyl disulphide, to several other odour components emitted by bat-pollinated flowers, and to scentless controls. In the field, at La Selva station in the tropical lowland rain forest of Costa Rica, G. commissarisi were attracted by two sulphur-containing compounds, dimethyl disulphide and 2,4-dithiapentane, to visit artificial flowers filled with sugar water. Thus, in nectarivorous bats the sense of smell obviously plays an important role in searching for and localising food sources, and even single components of the scent bouquets of bat-pollinated flowers are attractive. The preference for sulphur-containing odours seems to be innate.

Animals↗
PubMed1998

Clinical validation of a new olfactory test.

A new approach to clinical olfactometry is presented using nasal sprays. A special dosage valve was used to standardize an aerosol size to 40 microns. For evaluation a 6 x 6 matrix (substance/olfactory quality) with verbal associative clues was used according to test psychological findings. Validation took place in three steps after determining smell-associated thresholds in preliminary examinations. Recognition of different aromas administered either by spraying into the open mouth from a distance of 5 cm using nasal sprays or sniffing opened bottles was compared in 50 subjectively normosmic subjects. Findings showed that the correspondence between the two procedures was relatively high, with global identification of odorous substances as high as 98.4% in the spray test. The number of substances used was next reduced to those six substances providing the most reproducible results in an investigation with 56 normosmic and 55 hyposmic subjects. Verbal associative clues were also tested. In a last step 50 patients with hyposmia of various origin and 110 normosmic subjects were tested, allowing previous results to be reproduced regardless of the cause of hyposmia. The spray test was shown to be easily performed and was suitable as a screening test, with a sensitivity of 88% and a specificity of 100%.

Administration, Intranasal↗
PubMed1998

New units for indoor air quality: decicarbdiox and decitvoc.

Two new units are proposed for the evaluation of indoor air quality using the decibel concept, which give a much better approximation of the human perception of odour intensity, compared to the CO2 and total volatile organic compounds (TVOC) concentration scales: the decicarbdiox and the devitvoc. On the psychophysical scale according to Yaglou, the weakest odour that can be detected by the human smell sensors is equal to one, and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8%. It is equivalent to: (1) a CO2 threshold concentration of 485 ppm-0 dB (odour CO2)-0 dCd (decicarbdiox), and (2) a TVOC threshold concentration of 50 micrograms m-3-0 dB (odour TVOC)-0 dTv (decitvoc). The upper limit is determined by the initial value of toxicity: (1) CO2-15,000 ppm-134 dCd, and (2) TVOC-25,000 g/m-3-135 dTv. Optimal pollutant values (corresponding to PD = 20%) and admissible values (PD = 30%) for unadapted and adapted persons are calculated. Long-term tolerable values (determining the sick building syndrome range) and short-term tolerable values (the beginning of the toxic range) are also stated. The same system used to evaluate noise can be used to evaluate air quality. Additionally, the contribution of the individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained. The new units dCd and dTv can express an increase or decrease in air contamination, e.g. by the use of air cleaners, new building materials etc. The proposed system of using dCd and dTv is compatible with BSR/ASHRAE 62-1989 R which can be used to determine the required volume of fresh air for ventilation by an improved method, which takes into account different levels of required indoor air quality.

Air Pollution, Indoor↗
PubMed2006

Olfactory groove meningiomas: functional outcome in a series treated microsurgically.

BACKGROUND: A systematic investigation of long-term follow-up results after microsurgical treatment of patients harbouring an olfactory groove meningioma, particularly with regard to postoperative olfactory and mental function, has rarely been performed. We reassessed a series of patients treated microsurgically for an olfactory groove meningioma in regard to clinical presentation, surgical approaches and long-term functional outcome. METHOD: Clinical, radiological and surgical data in a consecutive series of 56 patients suffering from olfactory groove meningioma were retrospectively reviewed. FINDINGS: Presenting symptoms of the 41 women and 15 men (mean age 51 years) were mental changes in 39.3%, visual impairment in 16.1% and anosmia in 14.3% of the patients. Preoperative neurological examination revealed deficits in olfaction in 71.7%, mental disturbances in 55.4% and reduced vision in 21.4% of the cases. The tumour was resected via a bifrontal craniotomy in 36, a pterional route in 13, a unilateral frontal approach in 4 and via a supraorbital approach in 3 patients. Extent of tumour resection according to Simpson's classification system was grade I in 42.9% and grade II in 57.1% of the cases. After a mean follow-up period of 5.6 years (range 1-13 years) by clinical examination and magnetic resonance imaging (MRI), 86.8% of the patients resumed normal life activity. Olfaction was preserved in 24.4% of patients in whom pre- and postoperative data were available. Mental and visual disturbances improved in 88 and 83.3% of cases, respectively. Five recurrences (8.9%) were observed and had to be reoperated. CONCLUSIONS: Frontal approaches allowed better resection of tumours with gross infiltration of the anterior cranial base, tumours extending into the ethmoids or nasal cavity and in cases with deep olfactory grooves. Preservation of olfaction should be attempted in patients with normal or reduced smelling preoperatively.

Adult↗
PubMed1999

The extended transbasal approach: clinical applications and complications.

OBJECTIVES: To describe in detail key technical aspects of the extended transbasal approach which involves en-bloc mobilisation of the supraorbital rim, the orbital roof and the nasoethmoidal complex. In some patients osteotomies were performed around the cribriform plate with a view to maintaining olfaction. To review 18 patients with deep seated lesions located in the central skull base region (including 6 recurrences) to highlight patient selection, presentation, surgical morbidity and outcome. METHODS: Prospective data recording and clinical chart review. RESULTS: Outcome was assessed at a minimum of 1 year after operation using the Glasgow Outcome Score. Thirteen patients had made a good recovery, 1 was moderately disabled, 2 were severely disabled (both had been severely disabled before operation), and 2 died. By contrast, quality of life assessment indicated that only 7 of the surviving 14 adults had returned to normal levels of activity and perceived health; although 6 of the other 7 patients had resumed their former occupations, their follow up assessments showed a reduced quality of life. Of the 13 patients who had an olfaction preservation procedure, 6 showed appreciation of smell on formal testing. CONCLUSIONS: In patients with progressive and extensive deep seated lesions this technique provides wide exposure in a shallow surgical field. Complication rates although acceptable were significantly higher in patients with intradural lesions. In some selected patients it was possible to preserve olfaction. Specific surgical outcome assessments pointed to satisfactory results, but failed to reflect the degree of patient disability. There is a need for outcome measures that take into account the patient's expectations and which address his quality of life in order to validate the benefits of these procedures.

Adolescent↗
PubMed2005

Modern psychophysical tests to assess olfactory function.

The sense of smell significantly contributes to quality of life. In recent years much progress has been made in understanding the biochemistry, physiology and pathology of the human olfactory system. Olfactory disorders may arise not only from upper airway phlogosis but also from neurodegenerative disease. Hyposmia may precede motor signs in Parkinson's disease and cognitive deficit in Alzheimer's disease. These findings suggest the complementary role of olfactory tests in the diagnosis and management of neurodegenerative diseases. In this report we present a review of modern olfactory tests and their clinical applications. Although rarely employed in routine clinical practice, the olfactory test evaluates the ability of odour identification and is a useful diagnostic tool for olfaction evaluation. Olfactory screening tests are also available. In this work we strongly recommend the importance of an ENT evaluation before the test administration and dissuade from a self-administration of an olfactory test.

Humans↗
PubMed2025

Loss of responses to odorants and pheromones in mPRγ (paqr5b)-knockout zebrafish.

In our previous study, we generated a membrane-type progesterone receptor γ (paqr5b) knockout zebrafish line. Knocking out paqr5b by genome editing resulted in the loss of neurons in the olfactory rosette (OR). These findings indicated that Paqr5b plays an essential role in the formation of olfactory neurons. In this study, we investigated the extent to which paqr5b-/- fish lacking olfactory neurons retain their sense of smell. We used a reported tank for zebrafish olfactory analysis with a dividing plate in the middle. The tank was divided into three zones: the right zone, where test substances were added; the neutral zone; and the left zone. The fish were released into the neutral zone at the beginning of each test, the chemical was added to the corner of the right zone, and a 3-min video was taken to track the movements of the fish. The video was then played back, and the time spent in the three zones was counted manually. Both male and female paqr5b+/+ and paqr5b-/- zebrafish were separately analyzed for time spent in the three zones after exposure to ATP, cadaverine, and the pheromone 17α,20β-dihydroxy-4-pregnen-3-one (DHP). Both male and female paqr5b+/+ zebrafish were strongly attracted to ATP and stayed in the right zone for approximately 2 min (67%). In addition, paqr5b+/+ zebrafish avoided cadaverine and stayed longer in the left zone than in any other zone. In contrast, paqr5b-/- zebrafish stayed in all three zones for approximately the same amount of time, even after exposure to ATP and cadaverine. The paqr5b+/+ fish were attracted to DHP and stayed in the right zone longer. Paqr5b-/- zebrafish of either sex were not reactive to DHP exposure. These results showed that paqr5b-/- zebrafish lacking olfactory neurons lost responsiveness to odorants and pheromones.

Animals↗
PubMed2006

Olfaction and identification of unrelated individuals: examination of the mysteries of human odor recognition.

Although several studies have examined the effect of human odor on kin recognition and mate choice, few have focused on the impact of familiarity on recognition of nonrelatives by olfactory cues. As part of a program designed to engage students in scientific research, 53 high school students researched, planned, and implemented a project to analyze the effect of odor on human recognition of, and preference for, friends, sex, and self. A total of 37 students, including friends of their choosing, wore T-shirts for three consecutive nights. During that time, subjects were controlled for exposure to extraneous perfumes, household odors, and other humans. The students were then asked to smell a series of five shirts and evaluate them with respect to pleasantness. Students were also asked to identify the shirts belonging to themselves and their friend, and determine the sex of the person who wore each shirt. Although subjects were unable to distinguish sex by olfactory cues alone, a significant percentage of subjects were able to identify their own odor (51.6%), as well as distinguish the odor cue of their friend (38.7%). Additionally, subjects who could not identify their friend's cue were apt to choose the odor of a member of the opposite sex as their friend. This result was not believed to rely on odor preference as neither individual, friend, nor stranger odors were rated significantly different with respect to odor pleasantness. The ability to recognize friends via odor cues lends credence to the hypothesis that association and familiarity are important aspects of conspecific olfactory recognition in humans. Furthermore, this study augments evidence that olfaction may supplement visual and auditory cues used in human conspecific and kin recognition.

Adolescent↗