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PubMed2003

Genetic analysis of a complex trait in the Utah Genetic Reference Project: a major locus for PTC taste ability on chromosome 7q and a secondary locus on chromosome 16p.

The ability to taste phenylthiocarbamide (PTC) shows complex inheritance in humans. We obtained a quantitative measure of PTC tasting ability in 267 members of 26 large three-generation families that were part of a set of CEPH families that had been used for genetic mapping. Significant bimodality was found for the distribution of age and gender adjusted scores (P<0.001), with estimated means of 3.16 (SD=1.80) and 9.26 (SD=1.54). Using the extensive genotyping available in these families from the genetic mapping efforts, we performed a genome scan by using 1324 markers with an average spacing of 4 cM. Analyses were first carried out with a recessive genetic model that has traditionally been assumed for the trait, and a threshold score of 8.0 delineating tasters from non-tasters. In this qualitative analysis, the maximum genome-wide lod score was 4.74 at 246 cM on chromosome 7; 17 families showed segregation of the dichotomous PTC phenotype. No other lod scores were significant; the next highest score was on chromosome 10 (lod=1.64 at 85 cM), followed by chromosome 3 (lod=1.29 at 267 cM). Because PTC taste ability exhibited substantial quantitative variation, the quantitative trait was also analyzed by using a variance components approach in SOLAR. The maximum quantitative genome-wide lod score was 8.85 at 246 cM on chromosome 7. Evidence for other possible quantitative loci was found on chromosomes 1 (lod=2.31 at 344 cM) and 16 (lod=2.01 at 14 cM). A subsequent two-locus whole-genome scan conditional on the chromosome 7 quantitative trait locus identified the chromosome 16 locus (two-locus lod=3.33 at 14 cM).

Adolescent↗
PubMed2001

Effects of amiloride on gustatory neural responses to salts in the frog.

In frogs, the glossopharyngeal nerve (GL) innervates taste receptors on almost the entire tongue. The mandibular branch (MBF) and palatine branch (PN) of the facial nerve innervate taste receptors on a very small area at the base of the tongue and on the palate, respectively. In the present study, effects of amiloride, an epithelial sodium channel blocker, on the tonic responses of the GL, MBF and PN in frogs to NaCl, LiCl, KCl and CaCl(2) were investigated. In three nerves, amiloride at 0.5 mM, a relatively high concentration, did not affect the responses to 0.15 (concentration just above threshold)-0.5 M NaCl, 0.5 M LiCl and 0.3 M KCl, whereas it almost completely inhibited the response to 1.0 mM CaCl(2). Amiloride may exert an inhibitory action on the response to CaCl(2) by a competitive antagonism between Ca(2+) and a monovalent cation of amiloride, because the response to Ca(2+) is competitively inhibited by other cations such as Na(+) and Mg(2+). The lack of inhibitory effect of amiloride on the responses in the GL, MBF and PN to NaCl suggests that amiloride-sensitive sodium channels in the apical membrane of taste receptor cells are not involved in sodium taste transduction in frogs.

Amiloride↗
PubMed2006

Protein binding and astringent taste of a polymeric procyanidin, 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose, castalagin, and grandinin.

The objective of the present investigation was to examine the oral astringency and protein-binding activity of four structurally well-defined tannins, namely, procyanidin [epicatechin16(4-->8)catechin], pentagalloyl glucose (1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose), castalagin, and grandinin, representing the three main structural categories of tannins, the proanthocyanidins, the gallotannins, and the ellagitannins. Astringency threshold and dos/response were determined by the half-tongue test using a trained human panel. Protein-binding stoichiometry and relative affinity were determined using radioiodinated bovine serum albumin in precipitation or competitive binding assays. Procyanidin and pentagalloyl glucose were perceived as highly astringent compounds and had relatively steep dose/response curves, but castalagin and grandinin had a lower mass threshold for detection. In vitro, procyanidin was the most effective protein-precipitating agent and grandinin the least. Increasing the temperature increased protein precipitation by the hydrolyzable tannins, especially grandinin. All four polyphenols had higher relative affinities for proline-rich proteins than for bovine serum albumin.

Adult↗
PubMed2003

High-performance taste sensor made from Langmuir-Blodgett films of conducting polymers and a ruthenium complex.

A sensor array made up of nanostructured Langmuir-Blodgett (LB) films is used as an electronic tongue capable of identifying sucrose, quinine, NaCl, and HCl at the parts-per-billion (ppb) level, being in some cases 3 orders of magnitude below the human threshold. The sensing units comprise LB films from conducting polymers and a ruthenium complex transferred onto gold interdigitated electrodes. Impedance spectroscopy is used as the principle of detection, and the importance of using nanostructured films is confirmed by comparing results from LB films with those obtained from cast films.

Journal Article↗
PubMed2004

Quantitative structure-activity relationship modeling of alcohol, ester, aldehyde, and ketone flavor thresholds in beer from molecular features.

Three quantitative structure-activity relationship approaches-principal components regression, partial least-squares regression, and alternating conditional expectations-were used to investigate relationships between the flavor thresholds of 38 alcohols, 40 esters, 45 aldehydes, and 43 ketones in beer and their structures. Strong nonlinear relationships between the logarithm of the flavor threshold and four or five structure descriptors were found for each class of compounds (R2 = 0.920, 0.937, 0.920, and 0.928 for alcohols, esters, aldehydes, and ketones, respectively). Simple nonlinear relationships between the alcohol, ester, and aldehyde thresholds and the numbers of hydrogen atoms in the molecules were also demonstrated.

Alcohols↗
PubMed2006

Increased olfactory sensitivity in euthymic patients with bipolar disorder with event-related episodes compared with patients with bipolar disorder without such episodes.

OBJECTIVE: Some patients with bipolar disorder experience mood episodes following emotional life events, whereas others do not. There is evidence that orbitofrontal hypoactivity may be related to this, because the orbitofrontal cortex is involved in the regulation of emotional and behavioural responses to external events. The close anatomical and functional connection between the orbitofrontal cortex and olfactory processing suggests that patients with bipolar disorder and heightened emotional reactivity may exhibit altered olfactory function compared with patients with bipolar disorder who do not exhibit this sensitivity. METHODS: In this pilot study, olfactory function was assessed in patients with bipolar disorder and a history of event-triggered episodes (n = 7) and in patients with bipolar disorder without such a history (n = 9) at the Department of Psychiatry and the Taste and Smell Clinic of the University of Dresden, Germany. Each patient's bipolar disorder was in remission at study entry, and they were on monotherapy with mood stabilizers. Assessment included olfactory event-related potentials (ERP) and psychophysical tests for odour threshold, odour identification and olfactory quality discrimination. RESULTS: Odour thresholds were lower in patients with bipolar disorder and event-triggered episodes compared with the other patient group. In addition, patients with event-triggered episodes exhibited shorter N1 peak latencies of the olfactory ERP. CONCLUSIONS: Our findings indicate disinhibition of orbitofrontal areas involved in the processing of emotional events in a subset of patients with bipolar illness.

Adult↗
PubMed2005

The role of taste in food selection by African apes: implications for niche separation and overlap in tropical forests.

Ripe fruit eating shapes the behavior of most of the apes. Gorillas (Gorilla gorilla) and chimpanzees (Pan troglodytes) are very different sizes and, consequently, have been traditionally viewed as ecologically distinct, but few studies have explored the behavioral and physiological foundations of their diets. Debate continues on the extent that large-bodied gorillas may be less selective and more opportunistic fruit eaters than chimpanzees. Taste responses have been predicted to relate to body size and digestive strategies. This study employs laboratory research on taste perception and discrimination among captive zoo-housed chimpanzees and relates it to previous work on gorillas to better characterize diets and niche separation among these apes. During the captive trials, differences were recorded in consumption patterns of water and varying concentrations of dilute aqueous fructose (sweet) and tannic acid solutions (astringent), compounds commonly found in wild foods. The chimpanzees exhibited similar preference thresholds for fructose (50 mM) to other primates studied. They exhibited slightly lower inhibition thresholds for tannic acid solutions than gorillas, but higher than smaller primates studied to date. These preliminary findings suggest that tannin tolerance may well be mediated by body size, though possible species differences in salivary proteins or other sensory differences remain to be explored. This research furthers our efforts to understand the roles of body size and physiological adaptations in shaping diet and niche separation of chimpanzees and gorillas.

Animals↗
PubMed2003

Conditioned taste aversion learning in leptin-receptor-deficient db/db mice.

The db/db mouse has defective leptin receptors. The defects lead to impairments of leptin regulation of food intake and body weight, and result in the expression of diabetic symptoms such as hyperinsulinemia, hyperglicemia, and extreme obesity. Recent studies have proposed that leptin may also affect memory and learning processes. To examine this possibility, we compared the ability of leptin-receptor-deficient db/db mice and their normal lean litter mates to form and extinguish a conditioned taste aversion (CTA) for saccharin. We used a short-term (10 s) lick test and a long-term (48 h) two bottle preference test for measurement of consumption of test solutions. On the first day after conditioning to avoid saccharin, the db/db mice showed preference scores for saccharin as low, and aversion thresholds for sucrose lower than that of the lean mice. During the extinction test trials beginning from the second up to the 30th day after conditioning, numbers of licks and preference scores for aversive saccharin and sucrose appeared to be larger, and recovered faster to the control levels in db/db mice. These results indicate that db/db mice with leptin-receptor-deficiency may show equal capacity to form CTAs for saccharin, greater generalization from saccharin to sucrose, and a faster rate of extinction. This suggests that disruption of leptin signalling does not inhibit acquisition of CTA learning, but impairs its extinction. This differential contribution of the leptin system on CTA processes may be due to differential distribution of leptin receptors in the CTA-related brain areas.

Animals↗
PubMed1998

High-voltage electron microscopy and 3-D reconstruction of solitary chemosensory cells in the anterior dorsal fin of the Gadid fish Ciliata mustela (Teleostei).

Solitary chemosensory cells (SCCs) are secondary sensory cells present in the epidermis of most primary aquatic vertebrates. In rocklings, the epidermis of the anterior dorsal fin (ADF) contains approximately 5 million SCCs. High-voltage electron microscopy and three-dimensional reconstructions from serial sections were used to examine the ultrastructure, arrangement, and synaptic contacts of the SCCs in the rockling ADF. Approximately 15% of all cells in the fin ray epidermis are SCCs, which occupy roughly 30% of the epidermal volume. These spindle-shaped cells are 25-30 microm long and up to 10 microm wide and terminate apically in a microvillus protruding 2-5 microm above the epidermal surface. SCCs contain abundant endoplasmic reticulum and a large Golgi apparatus in their proximal regions. The distal parts of SCCs contain characteristic vesicles, elongate mitochondria, and longitudinal strands of intermediate filaments. Synapses between SCCs and nerves resemble those found in teleost taste buds. One to four synaptic contacts per SCC were found. We hypothesize that the apparent secretory activity of the SCCs serves to replenish the apical membrane and mucus. Furthermore, parallel sampling of several hundred SCCs by single nerve fibers may serve low-threshold detection rather than stimulus localization.

Animals↗
PubMed2004

Sucrose consumption enhances the analgesic effects of cigarette smoking in male and female smokers.

RATIONALE: Nicotine has analgesic actions in experimental animals and humans. Moreover, the analgesic properties of nicotine in experimental animals are increased by intake of sweet-tasting nutritive fluids. It is important to determine if the effects of diet on nicotine-induced analgesia are limited to experimental animals, or if these effects can be translated from the laboratory to clinical research situations. OBJECTIVE: This study investigated whether intake of a sweet-tasting sucrose solution would enhance the pain relieving actions of nicotine, administered in the form of cigarette smoking, in male and female college-aged students. The effects of smoking and sucrose intake on mood were also examined. METHOD: Using the cold pressor test, pain thresholds and pain tolerance were determined in 24 male and 25 female smokers. Each participant was tested 4 times. On 2 of the test days, participants drank a sucrose-containing beverage, and on 2 of the days, drank water. Twenty-five minutes later, participants either smoked a cigarette or did not smoke. Participants were tested 5 min later for their responses on the cold pressor test. To determine if mood was altered by smoking or sucrose intake, the Profile of Mood Scale was administered immediately preceding and following experimental manipulations. RESULTS: Cold threshold and cold tolerance were greater when participants were allowed to smoke than when they were not allowed to smoke. While men and women responded in a similar manner to the experimental manipulations, men displayed significantly greater cold threshold and cold tolerance than women. Sucrose consumption augmented the effects of smoking on cold threshold, but not on cold tolerance. Men reported feeling significantly more vigorous and less angry, and women reported feeling significantly less tense after they had smoked than when they had not smoked. Sucrose consumption did not alter self-reports of mood in either men or women. CONCLUSION: These findings suggest that sucrose augments the analgesic properties of nicotine in humans, as well as in experimental animals, and suggest that diet could serve as an adjunct in the control of pain.

Adolescent↗
PubMed2001

Vanillin content in boiled peanuts.

A high-performance liquid chromatographic (HPLC) method for determination of vanillin in boiled peanuts has been developed. Vanillin was extracted with acetonitrile by blending at high speed followed by purification of an aliquot of the extract on a minicolumn packed with Al(2)O(3). Vanillin was quantitated by HPLC on silica gel with n-hexane/2-propanol/water/acetic acid (2100/540/37/2, v/v) as a mobile phase. The recovery of vanillin added to fresh peanut hulls at 0.50 and 2.50 microg/g was 78.7 +/- 2.7 and 79.9 +/- 3.1%, respectively. The detection limit of vanillin in boiled peanuts was estimated at 0.05 microg/g. UV-detector response to vanillin was linear to at least 2.5 microg/injection. Free vanillin has been found in two commercial brands of boiled peanuts at low ppm levels. Both the kernels and the hulls contained vanillin, which was formed during hydrolysis of lignin, one of the major constituents of the peanut hulls. Since vanillin has a low flavor threshold, it could be considered as one of the major ingredients that determines the flavor of boiled peanuts.

Arachis↗
PubMed1998

Gustatory and food habit changes during the menstrual cycle.

Gustatory and food habit changes during the menstrual cycle were studied in 8 women, 6 smokers and 2 non-smokers, aged 23-37 years. The following parameters were evaluated during three consecutive menstrual cycles: blood oestradiol and progesterone levels on the 7th, 14th and 21st day of each cycle (radioimmunoassay); detection and recognition thresholds and concentration preferences for sucrose, sodium chloride, citric acid and quinine sulphate on the 1st, 7th, 14th and 21st day of each cycle; food consumption (weighed record) on days 1 and 2, 6-8, 13-15 and 20-22 each cycle. The four basic tastes were influenced differently by blood hormone levels during the menstrual cycle. Sensitivity to sweet taste increased with an increase of oestradiol, while sensitivity to bitter taste increased with an increase of progesterone. No correlations between hormone levels and acid taste, and only a few correlations for salt taste were found. Food habits changed during the cycle particularly for meat and fruit. Vegetables and cereals showed only a tendency to vary. In correspondence with the highest oestradiol values there was a tendency towards lower energy intake, -122 kcal (-0.51 MJ) = 8%, predominantly provided by carbohydrates (as bread).

Adult↗
PubMed1988

Amiloride inhibition of responses of rat single chorda tympani fibers to chemical and electrical tongue stimulations.

Amiloride inhibition of single fiber responses of the rat chorda tympani to ionic chemical and electrical tongue stimulations was studied. Amiloride reduced responses to both chemical and electrical stimulations with NaCl or LiCl in most of the single fibers. However, the magnitude of reduction of the response by amiloride varied among the fibers and was greater for chemical than electrical stimulation with NaCl in each fiber. Thirty-two single fibers were divided into two groups, such as 18 high (HAS) and 14 low amiloride-sensitive (LAS) fibers. Percent responses (control, 100%) of the former group to chemical stimulus with NaCl after amiloride ranged from 1.1 to 42.5%, while those of the latter from 72.8 to 108.0%. In HAS fibers, amiloride also reduced responses to KCl and CaCl2, but to a smaller degree than those to NaCl and LiCl. Fifteen out of 18 HAS fibers more strongly responded to a chemical stimulus with 0.1 M NaCl than 0.01 M HCl, while the opposite was true for 13 out of 14 LAS fibers, although the threshold concentration for NaCl was rather lower in LAS fibers than in HAS fibers. These results suggest that there exist at least two different receptor mechanisms for NaCl or LiCl which are amiloride-sensitive and -insensitive, and the observed differences in relative specificities to ionic taste stimuli and sensitivities to amiloride among rat chorda tympani fibers are possibly due to a disproportional distribution of these two receptors.

Amiloride↗
PubMed2003

Long-term hearing results after stapes surgery: a 20-year follow-up.

OBJECTIVE: The aim of this study was to evaluate the results of stapes surgery after 20 years of follow-up and to compare the results between large fenestra versus small fenestra stapedotomy. STUDY DESIGN: Retrospective clinical study. SETTING: Tertiary referral center (university hospital). PATIENTS: One hundred forty-two patients with otosclerosis treated by surgery. INTERVENTION: Eighty patients had a total stapedectomy with House-wire prosthesis and 62 patients a stapedotomy with Teflon-piston prosthesis. MAIN OUTCOME MEASURES: Preoperative, postoperative, and long-term hearing thresholds were compared. Patients filled in a questionnaire about the impact of surgery on the quality of life and postoperative symptoms. RESULTS: The long-term pure tone average improvement did not differ significantly between the techniques compared with the preoperative values. The air-bone gap tended to enlarge as a function of time. The change in the pure tone average was 0.9 dB per year for both techniques. In the questionnaire, some patients reported vertigo, tinnitus, loud noise intolerance, and taste disturbances. Loud noise intolerance seemed to persist in the long term. Surgery had no effect on preoperative tinnitus. CONCLUSIONS: There were no statistically significant differences between the techniques regarding hearing results. Over the long term, both techniques are safe and effective in restoring hearing and improving quality of life.

Adult↗
PubMed1975

Induction of physical dependence on alcohol in rodents.

An ethanol withdrawal syndrome consisting of tremors and seizures can be induced in rats and mice. This syndrome closely resembles the physical signs observed in human patients during alcohol withdrawal. The criteria for an animal model of a human disease appear to be fulfilled regarding the etiological agent, course of illness, the similarity of physical and electrophysiological manifestations and response to therapeutic agents. Therefore these models should lend themselves for the elucidation of the pathogenesis at the molecular level of biological organization and for the development of new therapeutic approaches. Criteria for an optimal animal model of ethanol dependence are outlined. Withdrawal signs are classified into minor (startle threshold and exploratory behavior) and major types (tremors and seizures). Methods for quantification of tremors and seizures are described. The procedures for induction of the major withdrawal signs are classified according to the mode of ethanol administration designed to circumvent the animal's inherent aversion to the taste of ethanol: Oral (free feeding, behavioral modifications of free feeding and force feeding), parenteral and inhalation. Auxiliary procedures consist of pyrazole administration and weight reduction resulting in a decreased rate of ethanol metabolism. Exposure to low environmental temperatures increases consumption of ethanol containing diets without proportionately increasing the rate of ethanol metabolism. Auxiliary procedures for the induction of seizures during withdrawal consist of handling the animals and audiogenic stimuli. Advantages and limitations of various rodent models are evaluated in terms of the procedures (practicability, compounding variables) and their results (reproducibility, severity and yield of major withdrawal signs, objective quantification). It is concluded that none of the current methods fulfill all requisites for all types of experiments. The selection of methods best suited for a particular experiment depend upon its objectives.

Acoustic Stimulation↗
PubMed2000

Identification and quantification of geosmin, an earthy odorant contaminating wines.

Musty, earthy odors are highly detrimental to the aromatic quality of wines. A characteristic aroma of freshly tilled earth, damp cellar was studied in some red and white wines of different origins. The extraction and purification of the wines marked by this odor have shown after analysis by gas chromatography-olfactometry a unique strong odorous zone having the same odor as the one perceived at tasting. The compound responsible for this odorous zone was identified by gas chromatography-mass spectrometry as geosmin (trans-1,10-dimethyl-trans-9-decalol), which possesses a distinctive earthy odor. Geosmin may be present in wines at levels higher than the racemic geosmin olfactory perception threshold, thus suggesting its contribution to their off-aroma. Moreover, the presence of this compound in juice taken from freshly crushed grapes suggests that microorganisms that develop on the grapes may contribute to the presence of this compound in wines.

Food Contamination↗
PubMed1992

Neuropharmacology of cocaine and ethanol dependence.

Drug addiction includes two important characteristics, chronic compulsive or uncontrollable drug use and a withdrawal syndrome when use of the drug is stopped. Animal models for the motivational components of drug dependence have been developed allowing a systematic exploration of the neurobiological mechanisms of drug dependence. The reinforcing actions of acute cocaine as measured by intravenous cocaine self-administration appear to be mediated by the presynaptic release of dopamine in the region of the nucleus accumbens and may preferentially involve the dopamine D-1 receptor subtype. The nucleus accumbens circuitry involved in the reinforcing actions of cocaine may include the ventral pallidum and may be modulated by serotonin. Chronic cocaine produces increases in brain reward thresholds that may reflect the "dysphoria" and anhedonia associated with cocaine dependence and suggests a dysregulation of brain reward systems possibly involving dopamine. Reliable measures for the acute reinforcing effects of ethanol in nondependent animals have been established in the rat using a lever press operant and a taste habituation procedure. Important roles have been established for serotonin, GABA, dopamine, and opioids in the acute reinforcing properties of ethanol, perhaps acting on some of the same neural circuitry subsuming the reinforcing actions of other drugs of abuse. Studies of the motivational aspects of ethanol dependence have suggested a functional role for brain corticotropin-releasing factor. These results suggest that the neurobiology of drug dependence involves not only neurotransmitters that mediate the acute reinforcing properties of drugs, but also the aversive motivational and emotional aspects of drug withdrawal. Advances in our understanding of brain changes associated with the switch from acute effects to chronic actions may provide a key to our understanding of not only drug dependence, but also psychopathology such as, anxiety, and affective disorders.

Alcoholism↗