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PubMed1995

A phenomenological study of sensory defensiveness in adults.

This article describes the experiences of five adults who are defensive toward sensations of touch, movement, vision, smell, sound, and taste that most people consider harmless. It also describes the strategies that they use when they perceive environmental stimuli to be aversive. These coping strategies are avoidance, predictability, mental preparation, talking through, counteraction, and confrontation. A conceptual framework is presented to enhance understanding and guide further study of sensory defensiveness in adults.

Adaptation, Psychological↗
PubMed2006

Soluble proteins in insect chemical communication.

Our understanding of the biochemical mechanisms that mediate chemoreception in insects has been greatly improved after the discovery of olfactory and taste receptor proteins. However, the presence of soluble polypeptides in high concentration around the dendrites of sensory neurons still poses unanswered questions. More than 2 decades after their discovery and despite the wealth of structural information available, the physiological function of odorant-binding proteins is not well understood. More recently, members of a second family of soluble polypeptides, the chemosensory proteins, were also discovered in the lymph of chemosensilla. Here we review the structural properties of both classes of soluble proteins, their affinity to small ligands, and their expression in the different parts of the insect body and subcellular localisation. Finally, we discuss current ideas and models of the role of such proteins in insect chemoreception.

Amino Acid Sequence↗
PubMed2006

Sodium ingestion in oxytocin knockout mice.

Under certain circumstances, central oxytocin (OT) pathways inhibit dietary intake of NaCl in rats and mice. C57BL/6 OT knockout (OT KO) mice were reported to consume greater amounts of saline solution than wild type (WT) cohorts when both were water deprived overnight. In this study, we determined that OT KO and WT mice of C57BL/6 strain demonstrate an equivalent taste aversion for continuously available 0.2 M, 0.3 M or 0.5 M NaCl. The aversion was proportional to the concentration of NaCl, similar to what has been reported in rats. Furthermore, OT KO and WT animals ingested the same daily amounts of a low, 0.01%, regular, 1.0%, and a high, 8.0%, NaCl diet that was provided ad libitum as a single choice. While consuming these diets, mice were given the choice to drink water or saline (0.5 M NaCl). As the amount of NaCl in the diet increased, mice of both genotypes significantly decreased the consumption of saline solution to an equal degree. Additionally, in an experimental model of sustained dehydration previously developed in rats, 0.5 M NaCl was the only available drinking fluid. Like rats subjected to this paradigm, OT KO and WT mice decreased food intake, decreased body weight and increased fluid ingestion with no genotypic differences. These findings suggest that oxytocinergic neuronal pathways cannot be the only regulator of ad libitum intake of NaCl in drinking solutions or diet. It appears that OT pathways may be more critical in controlling NaCl intake over brief intervals when an animal is quickly compensating for a dehydrating stimulus.

Analysis of Variance↗
PubMedDate not supplied

Zinc deficiency in elderly patients.

Zinc is needed for growth and development, DNA synthesis, neurosensory functions, and cell-mediated immunity. Although zinc intake is reduced in elderly people, its deficiency and effects on cell-mediated immunity of the elderly have not been established. Subjects enrolled in "A Model Health Promotion and Intervention Program for Urban Middle Aged and Elderly Americans" were assessed for nutrition and zinc status. One hundred eighty healthy subjects were randomly selected for the study. Their mean dietary zinc intake was 9.06 mg/day, whereas the recommended dietary allowance is 15 mg/day. Plasma zinc was normal, but zinc in granulocytes and lymphocytes were decreased compared with younger control subjects. Of 118 elderly subjects in whom zinc levels in both granulocytes and lymphocytes were available, 36 had deficient levels. Plasma copper was increased, and interleukin 1 (IL-1) production was significantly decreased. Reduced response to the skin-test antigen panel and decreased taste acuity were observed. Thirteen elderly zinc-deficient subjects were supplemented with zinc, and various variables were assessed before and after zinc supplementation. Zinc supplementation corrected zinc deficiency and normalized plasma copper levels. Serum thymulin activity, IL-1 production, and lymphocyte ecto-5'-nucleotidase increased significantly after supplementation. Improvement in response to skin-test antigens and taste acuity was observed after zinc supplementation. A mild zinc deficiency appears to be a significant clinical problem in free-living elderly people.

5'-Nucleotidase↗
PubMedDate not supplied

Possibility of spontaneous drug abuse tested in rat.

Given that a number of the techniques used to test drug abuse liability are not free from criticism, a series of oral free-choice experimental procedures was adopted. When simultaneously offered as alternatives to glucose using the classical polydipsic procedure, no preference for buprenorphine (0.025 mg/ml), morphine (0.5 mg/ml) or fentanyl (0.005 mg/ml) solutions was shown by premedicated rats. The same result was obtained when the two-bottle procedure was used for at least one month to offer etonitazene (10 micrograms/ml), buprenorphine (60 micrograms/ml), cocaine (300 micrograms/ml) and haloperidol (25 micrograms/ml) solutions as simultaneous alternatives to aspartame. This absence of preference was maintained even when the rats showed evident pharmacological effects and, in the case of the opiates, tolerance and withdrawal syndrome. However, when a gustatory marker (quinine) was introduced into one of the two solutions, preference was always shown for the other. Finally, in a conditioned taste aversion (CTA) test, etonitazene (5 or 40 micrograms/kg, i.p.) and haloperidol (0.5 or 2 mg/kg, i.p.) did not induce any reduction in saccharin consumption, while morphine (40 mg/kg) did. Pretreatment with naloxone (120 micrograms/kg, i.c.v.) did not antagonize morphine-induced CTA, while it did antagonize morphine-induced analgesia.

Animals↗
PubMed2006

NMDA receptor antagonist MK-801 infused into the insular cortex prevents the attenuation of gustatory neophobia in rats.

Gustatory neophobia dissipates with repeated exposures to an initially novel taste solution. The aim of the present study was to determine whether NMDA receptors in the insular cortex are involved in this experience-dependent process. Results showed that acute microinfusion of MK-801 into the insular cortex prevented the attenuation of gustatory neophobia indicating that this process is an NMDA receptor-dependent phenomenon.

Animals↗
PubMed2006

The role of fat in flavor perception: effect of partition and viscosity in model emulsions.

Decreasing the fat content of a food, while maintaining the same aroma content, changes both aroma release (due to partition effects) and the viscosity of the food. To understand the relative contribution of these two factors on flavor perception, a series of flavored emulsions were prepared to control aroma release and viscosity using different aroma, oil, and hydroxypropyl methyl cellulose (HPMC) contents. Samples were formulated to deliver the same aroma-release in vitro and in vivo, and their viscosity was measured using the Kokini oral shear stress parameter. Despite the in vivo aroma release being constant, there were perceptual differences between the samples, and the flavor intensity decreased as in-mouth viscosity increased. For these iso release samples, the Kokini oral shear stress parameter correlated well with the decrease in perception, suggesting that there may be a viscosity stimulus or that the viscosity affects release of tastant and hinders aroma-taste interactions.

Adult↗
PubMed2006

Novelty preference predicts place preference conditioning to morphine and its oral consumption in rats.

Sensation seeking is frequently observed among drug addicts. This behaviour has been modelled in non-primate animals as novelty seeking. We previously determined that novelty preference did not predict amphetamine-induced place conditioning but was positively correlated with the consumption of a low concentrated amphetamine solution. Here, we studied the relationship between novelty seeking and the vulnerability to rewarding and reinforcing effects of morphine. Wistar rats were selected according to their novelty preference. In this model, animals have free choice between a new compartment and a "familiar" compartment to which they were previously exposed during two 30-min sessions, 24 h apart. We measured oral morphine consumption when this drug was presented in tap water (25 or 50 mg/l) in free choice with water or when it was presented (50 mg/l) in a 5% (w/v) sucrose solution in free choice with a sucrose solution. The oral consumption of quinine was also measured. The rewarding effect of morphine (1.25 and 5 mg/kg; i.p.) was determined in a conditioned place preference paradigm. Whereas high and low novelty seekers did not differ in reactivity to the aversive taste of quinine, preference for novelty was associated with a greater oral morphine consumption as well as an increased conditioned place preference induced by the 5 mg/kg dose of morphine. The present results support the hypothesis that novelty preference predisposes to drug abuse.

Administration, Oral↗
PubMed1985

Glucocorticoid and other hormonal substrates of conditioned taste aversion.

Results of research reported in this paper show that lithium chloride (LiCl) injection causes a marked and prolonged elevation of adrenocorticotropic hormone (ACTH) and corticosterone. Peak elevations occur within 30 min after injection and continue for 60 to 120 min depending upon the molarity of the LiCl solution. CS preexposures do not alter the pituitary-adrenal response to LiCl. Although this response occurs, evidence argues that pituitary-adrenal activity is neither a sufficient nor essential condition for CTA to occur. It is possible that this prolonged ACTH secretion, which would be essential to maintain corticosterone levels elevated for one to two hours, is acting as a component of the unconditioned response associated with LiCl injections. Under certain types of extinction (forced extinction) the P-A system is activated. Thus, when an animal drinks an aversive solution following deprivation, intake of the solution causes a conditioned elevation of plasma corticosterone. Two measures of CTA, behavioral and hormonal, do not always coincide with one another. Preexposure to the CS alters both behavioral and corticosterone indices of CTA. These two systems will show either a coupling (e.g., parallel change) or a dissociation depending on the number of preexposures prior to conditioning. Manipulating the hormones associated with the pituitary-adrenal system also affects the acquisition of CTA and influences extinction. Thus, if one pretests with dexamethasone phosphate (DEX) prior to the administration of LiCl, CTA is attenuated. It would appear that ACTH is involved in the acquisition of CTA since a central block of ACTH also affects the magnitude of the aversion. If ACTH is injected during recovery, animals show a prolonged suppression of drinking. These data appear to be best explained using a memory-retrieval model. The manipulation of hormones and their effects on CTA appear to follow the effects observed endogenously. Thus, ACTH administered to rats during the conditioning phase does not appear to have any effect upon the learning of the aversion. Since LiCl markedly elevates ACTH, as indicated by prolonged elevations of corticosterone, the additional ACTH given exogenously at the time of conditioning does not appear to add to the effects already attributable to endogenous ACTH. Conversely, DEX given during recovery appears to have no effect upon the recovery function. Because endogenous levels of ACTH are already low during the free extinction procedure, DEX treatment does not appear to further reduce ACTH and has no effect upon recovery.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Cortex↗
PubMed2006

Heritability estimates for dental caries and sucrose sweetness preference.

OBJECTIVE: The aim of this study was to determine heritability estimates for dental caries traits and sucrose sweetness preference. DESIGN: Participants included 115 pairs of twins 4-7-years-old. Caries exams followed NIDCR criteria where the severity of the lesion was also determined. Twins ranked their preference for five concentrations of sucrose/grape juice solutions (0.15-1.17M) with a Face Scale. Variables submitted to analysis: (1) surface-based caries prevalence rate (SBCPR); (2) lesion severity index (LSI); (3) sucrose sweetness preference score (SSPS). Heritability analyses were performed with the SOLAR software package. RESULTS: Heritability estimates adjusted for age and gender were: SBCPR-h(2)=64.6 (p<.00001), LSI-h(2)=61.7 (p<.00001) and SSPS-h(2)=55.2 (p<.00001). Treating SPSS as a covariate in the SBCPR and LSI models did not alter heritability estimates. CONCLUSIONS: These results suggest that variation in dental caries traits and sucrose sweetness preference have a significant genetic contribution that is mediated independently.

Child↗
PubMed1978

Task-dependent genetic influences on behavioral response of mice (Mus musculus) to acetaldehyde.

Acetaldehyde was employed as a pharmacological agent in behavioral tests designed to assess genetic influences upon response to the drug. When used as a poison in a conditioned taste aversion study, acetaldehyde was more effective at inducing aversions in DBA/2J mice than in C57BL/6J mice. In another experiment, however, C57 mice were more affected than were DBA mice by acetaldehyde effects on loss of righting reflex. Implications for postulated genetic control of ethanol preference and neurosensitivity are discussed.

Acetaldehyde↗
PubMed2003

Overweight children overeat after exposure to food cues.

Overweight is becoming more common in children, but we know nearly nothing about the eating behavior of overweight children. Learning theory predicts that overeating follows from learned associations between the smell and taste of palatable food on the one hand and intake on the other hand. It was tested whether overweight children overeat after confrontation to these cues. They indeed failed to regulate food intake after both the exposure to the intense smell of tasty food (without eating it) and after eating a small preload of appetizing food, whereas normal-weight children decreased their intake after both cues. Overweight children are thus more vulnerable to triggers of overeating. Their overeating was not related to psychological factors like mood, body esteem, and a restrained eating style, but it was related to cue-elicited salivation flow. Apart from supporting the cue reactivity model of overeating, the data point to an interesting satiety phenomenon in normal eaters after prolonged and intense smelling palatable food without eating it.

Journal Article↗
PubMed2006

The anorexia of aging in humans.

Energy intake is reduced in older individuals, with several lines of evidence suggesting that both physiological impairment of food intake regulation and non-physiological mechanisms are important. Non-physiological causes of the anorexia of aging include social (e.g. poverty, isolation), psychological (e.g. depression, dementia), medical (e.g. edentulism, dysphagia), and pharmacological factors. Physiological factors include changes in taste and smell, diminished sensory-specific satiety, delayed gastric emptying, altered digestion-related hormone secretion and hormonal responsiveness, as well as food intake-related regulatory impairments for which specific mechanisms remain largely unknown. Studies in healthy elderly individuals have shown that men who consume diets over several weeks providing either too few or too many calories relative to dietary energy needs subsequently do not compensate for the resulting energy deficit or surplus when provided an ad libitum diet. Healthy elders have also been shown to be less hungry at meal initiation and to become more rapidly satiated during a standard meal compared to younger adults. Studies in animal models are required to investigate potential mechanisms underlying these observations, while human studies should focus on examining the potential consequences of this phenomenon and practical therapeutic strategies for the maintenance of appropriate energy intake with increasing age. In light of this need, we have recently demonstrated that low reported hunger assessed using a simple questionnaire predicts unintentional weight loss in a sample of healthy older women, and thus may provide a clinically useful tool for identifying older individuals at risk for undesirable weight change and therefore at high priority for intervention.

Aging↗
PubMed2002

The role and importance of research and scholarship in dental education and practice.

Understanding the role and importance of research and scholarship in dental education and practice requires an appreciation of dentistry as a learned profession. A foundational attribute for the members of such a profession has to be sheer intellectual curiosity--a trait as important for the clinician as for the scientist. That improved patient care results from technical advances made possible through research is not seriously disputed by anyone. What is less apparent, however, is the role for research in the education of dentists and in the broader life of dental schools. Accosting this matter requires a distinction to be made between research and scholarship: while all research qualifies as scholarship, not all scholarship qualifies as research. Though the exact role of research in the educational process is open to debate, the importance of scholarship is not. An education colored by research is one way of achieving the intellectual rigor necessary for the professional. The key is cultivating in students a taste for complexity, for problems, and for problem solving. All dental schools without exception need to help students acquire this taste. In doing so, they will generate a few scientists; but, more importantly, they will create out of every graduate a man or woman of science. Only by becoming a person of science is there any hope that the practitioner will be able to acquire and assimilate new knowledge and to adapt to the changes in practice and in the profession that the future requires.

Dental Research↗
PubMed2006

First-year medical students prefer multiple learning styles.

Students have preferences for the ways in which they receive information. The visual, auditory, reading/writing, kinesthetic (VARK) questionnaire identifies student's preferences for particular modes of information presentation. We administered the VARK questionnaire to our first-year medical students, and 166 of 250 students (66%) returned the completed questionnaire. Only 36.1% of the students preferred a single mode of information presentation. Among these students, 5.4% preferred visual (learning from graphs, charts, and flow diagrams), 4.8% preferred auditory (learning from speech), 7.8% preferred printed words (learning from reading and writing), and 18.1% preferred using all their senses (kinesthetics: learning from touch, hearing, smell, taste, and sight). In contrast, most students (63.8%) preferred multiple modes [2 modes (24.5%), 3 modes (32.1%), or 4 modes (43.4%)] of information presentation. Knowing the students preferred modes can 1) help provide instruction tailored to the student's individual preference, 2) overcome the predisposition to treat all students in a similar way, and 3) motivate teachers to move from their preferred mode(s) to using others.

Humans↗
PubMedDate not supplied

Relationships between flavour, lipid composition and antioxidants in organic, free-range and conventional chicken breasts from modelling.

Consumers expect organic, free-range and corn-fed chicken to be nutritionally wholesome and have premium flavour characters. Interrelationships between flavour, fatty acids and antioxidants of retailed breasts were explored using simple correlations and chemometrics. Saturated fatty acid C16:0, and n-6 polyunsaturated C20:4 and C22:4 contents were correlated with lipid oxidation products (thiobarbituric acid reactive substances) and in partial least-squares regression (PLS1) with 32 high-resonance gas chromatography (flame ionization) flavour components (r2>0.90), and also linked (r2>0.80) to antioxidants (alpha-tocopherol, glutathione and catalase). A further 10 high-resonance gas chromatography nitrogen phosphorus detector flavour components were correlated (r2>0.85) with C18:3(n-3) content. Chicken character was correlated with C18:3(n-3), and C18:3(n-6) inversely with oily, off-flavour and lipid oxidation. Sweet, fruity and oily aromas were linked in PLS1 with 13 specific fatty acids (r2>0.6), and bland taste with total summed (six) fatty acid fractions (r2>0.81). Specific antioxidants were correlated with sweet, fruity and chicken aromas, and alpha-tocopherol inversely with lipid oxidation. PLS2 confirmed relationships between fatty acid composition, antioxidants and the subsets of 32 and 10 flavour components. Clear relationships were thus observed between lipid and antioxidant compositions and flavour in chicken breast meat.

Animal Husbandry↗
PubMed1991

What is learned during opiate withdrawal conditioning? Evidence for a cue avoidance model.

How conditioned opiate withdrawal gives rise to avoidance behaviour was examined using a defensive burying procedure in rats made dependent with a morphine pellet. The subjects underwent withdrawal precipitated by naloxone (0.1 mg/kg, SC) on two or three occasions in a box containing only a small object. When exposed to the object in the presence of sawdust one or more days later, the subjects avoided contact and buried this object, i.e., pushed and piled the sawdust against it. The behaviour was seen only when withdrawal had been paired with the object, which was the case even with a choice of objects on the test. Approach but no burying was seen in nondependent animals when the object was paired with 1 mg/kg morphine. Burying, therefore, was concluded to be a defensive response elicited in rats by an object specifically paired with precipitated opiate withdrawal. Consideration of burying and other defensive responses reported to be elicited by cues of withdrawal (conditioned place and taste aversion, and suppression), with respect to the behavioural demands of these responses and the test conditions needed to see them, suggested that a goal of avoidance may be a primary event encoded in a withdrawal cue, as is known for predictors of nonpharmacological noxious events (e.g., shock).

Animals↗
PubMed2003

Experimental studies of adult Drosophila chemosensory behaviour.

Drosophila melanogaster is a powerful animal model to study the processes underlying behavioural responses to chemical cues. This paper provides a review of the important literature to present recent advances in our understanding of how gustatory and olfactory stimuli are perceived. An overview is given of the experimental procedures currently used to characterize the fly chemosensory behaviour. Since this species provides extremely useful genetic tools, a focus is made on those allowing to manipulate behaviour, and hence to understand its molecular and cellular bases. Such tools include single-gene mutants and the Gal4/UAS system. They can be combined with studies of the natural polymorphism of behavioural responses. Recent data obtained with these various approaches unravel some important aspects of taste and olfaction. These appear as rather complex processes, as revealed by results showing dose-dependence, plasticity and sexual dimorphism. Taken together, these results and the available tools open interesting perspectives for the years to come, in our attempts to make the link between genes and behaviour.

Journal Article↗