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At least 487 records · Page 27Linked to original sources

Cream and sugar: human preferences for high-fat foods.

Sixteen normal-weight subjects rated the perceived intensity of sweetness, fatness, and creaminess of 20 different mixtures of milk, cream, and sugar, and assigned an overall pleasantness (hedonic) rating to each sample. Intensity estimates increased as power functions of ingredient concentration and no significant mixture suppression effect was observed. In contrast, hedonic responses strongly depended on the relative proportions of sucrose and fat in the samples tasted. Hedonic preference ratings first rose and then declined with increasing sucrose concentration, but continued to rise with increasing dairy fat content. The addition of sucrose greatly enhanced hedonic ratings for high-fat stimuli. Changes in hedonic responsiveness were monitored using a mathematical modelling technique known as the Response Surface Method, which allows computerized simulation of the hedonic response surface as a function of perceived ingredient levels. Overnight fasting did not affect the perception or hedonics for sweet or "fatty" tastes. The observed preference for sweetened high-fat foods may have implications for the development of dietary-induced obesity in man.

Adult↗

Gompertzian growth and decay: a powerful descriptive tool for neuroscience.

First-order kinetics is based on simple exponential decay, usually expressed in base e (Naperian) notation. "Nonexponential" processes, for example, S-shaped functions, are frequently modeled as sums of that elemental construct, and the number of rate constants increases with the number of such terms. A powerful descriptive alternative to sums of simple exponentials is the Gompertz function. In Gompertz kinetics, the rate coefficient of an exponential process is assumed to change exponentially with the independent variable. Nonexponential processes are easily modeled, more efficiently and more accurately than is possible with standard kinetics. Application of Gompertz kinetics to neuroscience research topics ranging from cognitive to molecular is presented to illustrate the power of the model: distribution of nerve fiber diameters, conditioning-testing responses of excitable nerve, psychophysical estimates of taste intensity magnitude, time course of synaptic current, and behavior of membrane conductance during voltage clamp of squid axon.

Animals↗

A reconsideration of the relevance of recent animal studies for development of treatment procedures for alcoholics.

Amit and Sutherland's conclusions concerning the use of conditioned taste aversions for alcoholism treatment are critically evaluated. Their conclusion that painful electric shock is contraindicated as a basis for alcohol taste aversions is consistent with the animal and human literature which depicts nausea as a more biologically appropriate US for taste aversion formation. However, Amit and Sutherland also conclude that alcoholics will not develop illness-induced alcohol aversions because animal studies show that aversion acquisition is disrupted by preconditioning familiarity with the conditioned stimulus (CS) - flavor - or unconditioned stimulus (US) - illness. This conclusion is untenable because Amit and Sutherland only considered animal conditioning methods that differed markedly from aversion therapy practices. Other animal studies modeled after aversion therapy procedures clearly show CS and US preexposure effects to be transitory phenomena. Moreover, experimental and clinical data show humans to be quite susceptible to taste aversion formation, and that many alcoholics do form strong alcohol aversions under appropriate conditioning parameters. Additional implications of the animal literature for effective aversion therapy are explored, and the paper concludes with a discussion of covert sensitization, a promising verbal aversion therapy which has resulted in the development of strong alcohol aversions in many volunteer subjects at the Augusta Veterans Administration Medical Center.

Alcoholism↗

Complex quality traits: now time to model.

A recently published dynamic peach model by Françoise Lescourret and Michel Génard simulates changes in quality during final stages of fruit growth. It predicts quality, emerging from complex processes and influenced by environment and management, remarkably well and describes complex emerging behaviour. The model could prove an excellent tool to integrate novel insight from metabolic profiling and pathways of taste-related compounds, ultimately enabling the analysis of gene networks responsible for fruit maturation processes.

Crops, Agricultural↗

The syntaxin binding protein 1 gene (Stxbp1) is a candidate for an ethanol preference drinking locus on mouse chromosome 2.

BACKGROUND: We previously mapped a quantitative trait locus (QTL) for ethanol preference drinking to mouse chromosome 2 (mapped with high confidence, LOD = 15.5, p = 3 x 10(-16)). The specific gene(s) in the QTL interval responsible for phenotypic variation in ethanol preference drinking has not been identified. METHODS: In the current study, we investigated the association of the syntaxin binding protein 1 gene (Stxbp1) with ethanol preference drinking and other ethanol traits using a panel of B6 x D2 (BXD) recombinant inbred (RI) strains derived from the C57BL/6J (B6) and DBA/2J (D2) inbred mouse strains. Confirmation analyses for ethanol consumption and withdrawal were performed using a large B6D2 F2 cross, short-term selected lines derived from the B6 and D2 progenitor strains, and standard inbred strains. RESULTS: BXD RI strain analysis detected provisional associations between Stxbp1 molecular variants and ethanol consumption, as well as severity of acute ethanol withdrawal, ethanol-conditioned taste aversion, and ethanol-induced hypothermia. Confirmation analyses using three independent genetic models supported the involvement of Stxbp1 in ethanol preference drinking but not in ethanol withdrawal. CONCLUSIONS: Stxbp1 encodes a Sec1/Munc18-type protein essential for vesicular neurotransmitter release. The present study provides supporting evidence for the involvement of Stxbp1 in ethanol preference drinking.

Alcohol Drinking↗

The stability of dichlofluanid and vinclozolin and their influence on the quality of strawberries.

The content of dichlofluanid and vinclozolin found on strawberries treated with Euoparen and/or Ronilan, respectively, did not exceed the residue tolerance. Further decrease of the amount of these fungicides occurred during heatsterilisation of the fruit and storage of the products. The rate of decomposition of dichlofluanid and/or vincolozolin in model solutions (pH 3.0-6.0) followed pseudo-first-order kinetics. The taste and flavour of untreated fruit was preferred to those of strawberries treated with fungicides. There were differences in the content of reducing sugars, volatile fatty acids and titrable acidity in individual samples. Gas-chromatographic profiles of volatile substances isolated from treated and untreated berries also differed.

Aniline Compounds↗

Predictive neural coding of reward preference involves dissociable responses in human ventral midbrain and ventral striatum.

Food preferences are acquired through experience and can exert strong influence on choice behavior. In order to choose which food to consume, it is necessary to maintain a predictive representation of the subjective value of the associated food stimulus. Here, we explore the neural mechanisms by which such predictive representations are learned through classical conditioning. Human subjects were scanned using fMRI while learning associations between arbitrary visual stimuli and subsequent delivery of one of five different food flavors. Using a temporal difference algorithm to model learning, we found predictive responses in the ventral midbrain and a part of ventral striatum (ventral putamen) that were related directly to subjects' actual behavioral preferences. These brain structures demonstrated divergent response profiles, with the ventral midbrain showing a linear response profile with preference, and the ventral striatum a bivalent response. These results provide insight into the neural mechanisms underlying human preference behavior.

Adult↗

Mechanism of the electric response of lipid bilayers to bitter substances.

In order to clarify by what mechanism the lipid bilayer membrane changes its potential under the stimulation of bitter substances, a microscopic model for the effects of the substances on the membrane is presented and studied theoretically. It is assumed that the substances are adsorbed on the membrane and change the partition coefficients of ions between the membrane and the stimulation solution, the dipole orientation in the polar head, and the diffusion constants of ions in the membrane. It is shown, based on the comparison of the calculated results with the experimental ones, that the response arises mainly from a change in the partition coefficients. Protons play an essential role in the membrane potential variation due to the change in their partition coefficients. The present model reproduces the following observed unique properties in the response of lipid bilayers to bitter substances, which cannot be accounted for by the usual channel model for the membrane potential: 1) the response of the membrane potential appears even under the condition that there is no ion gradient across the membrane, 2) the response remains even when the salt in the stimulating solution is replaced with the salt made of an impermeable cation, and 3) the direction of the polarization of the potential is not reversed, even when the ion gradient across the bilayer is reversed.

Biophysical Phenomena↗

Do economic constraints encourage the selection of energy dense diets?

Economic constraints, by inducing the selection of low cost energy dense diets, could indirectly be responsible for the high prevalence of obesity in low socio-economic status groups. Diet optimisation by linear programming was used to test this hypothesis, by examining the relationship between the cost and the energy density (ED) of modelled diets. Models were developed that minimized the departure from the mean adult French diet estimated from a cross-sectional dietary survey. Palatability constraints were introduced into all models. The impacts of cost on ED and of ED on cost were explored by introducing and strengthening first a constraint on cost and then a constraint on ED. Forcing the cost of the linear programming diets to decrease induced a strong increase in their EDs. In contrast, forcing the ED to increase induced only a moderate decrease in diet costs. These results suggest that, although an energy dense diet can be selected at a relatively high cost, when cost is not influencing food choices, an energy dense diet will be preferentially selected to maintain habitual French dietary patterns when the budget for food is low. This supports the hypothesis that economic constraints play a role in the high prevalence of obesity in low-income people.

Adult↗

Interactions between artificial saliva and 20 aroma compounds in water and oil model systems.

The interactions between saliva components and 20 aroma compounds in water and oil model systems were systematically evaluated as a function of saliva composition and saliva/model system ratio. Air/liquid partition coefficients of dimethyl sulfide, 1-propanol, diacetyl, 2-butanone, ethyl acetate, 1-butanol, 2-pentanol, propyl acetate, 3-methyl-1-butanol, ethyl butyrate, hexanal, butyl acetate, 1-hexanol, 2-heptanone, heptanal, alpha-pinene, 2-octanone, octanal, 2-nonanol, and 2-decanone were determined by static headspace gas chromatography. Chain length of compounds within the homologous series determined the extent of interactions with the model system or saliva. Salts in the artificial saliva hardly interacted with aroma compounds. On the other hand, saliva proteins lowered retention of highly volatile compounds and increased retention of less volatile, hydrophobic compounds. Significant differences in volatility of compounds when artificial saliva or water was added indicated that saliva could not be sufficiently replaced by water. The model system/saliva ratio influenced air/liquid partitioning of the aroma compounds significantly for both model systems. Although saliva composition affected volatility of the aroma compounds, the saliva/model system ratio was of much greater influence.

Chromatography, Gas↗