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Biomedical subjects

D A Booth

Publications and source records attributed to D A Booth.

At least 55 records · Page 3Linked to original sources
PubMed1989

Genuinely olfactory preferences conditioned by protein repletion.

Effects of protein on mild food deprivation in the rat conditioned a relative preference for an intense, insoluble and tasteless odorant. This learned preference for the protein-paired odorant over a non-nutritive-paired odorant was temporarily obliterated by insertion of tubes in the nares to bypass the olfactory mucosa. This demonstrates truly olfactory conditioning, contrary to assertions that gustatory conditioning had not been excluded.

Animals↗
PubMed1989

Measurement of food perception, food preference, and nutrient selection.

Perception, preference, and selection are all objectively measurable performances that discriminate between different levels of entities such as the sugar, thickener, or protein in a food. A rating or an intake may not be controlled by the word that the experimenter or the subject uses to describe it: "protein"-oriented food selection, "thickness" preference, or "sweetness" perception is proved only when the named objective influence, isolated from any other influence, accounts for the observed variations in choice response. Difference-measuring designs can be extended from merely two levels of an influence to a continuum over the natural range of levels, thus evoking linear psychophysical (dose-response) performance from which the strength of that influence can be estimated. Usually, at least a few influences are operative at once on a choice. Because the interactions may vary among people, the only valid causal analysis is at the individual level. Examples are given of food taste tolerance in the elderly, integration of sensory and attitudinal influences, and dietary choices misattributed to carbohydrate craving.

Adult↗
PubMed1988

Fenfluramine and amphetamine suppress dietary intake without affecting learned preferences for protein or carbohydrate cues.

The effects of pharmacological modulation of monoamine transmitter activity on genuine nutrient selection were assessed: that is, drug-induced changes in nutrient-specific dietary choice behaviour were measured, using rats that had learned to select an odour cueing protein content or carbohydrate content of the diet. Anorexigenic doses of DL-fenfluramine-HCl (1.25 or 2.5 mg/kg) and D-amphetamine2 SO4 (0.5 or 1.0 mg/kg) did not affect the selection of protein-paired or carbohydrate-paired odours by trained rats. This weighs against the claim that 5-hydroxytryptamine or catecholamine transmitters are involved in the selection of macronutrients, as distinct from selection between diets in response to sensory differences functionally unrelated to nutrient composition.

Animals↗
PubMed1988

Effects of dl-fenfluramine and xylamidine on gastric emptying of maintenance diet in freely feeding rats.

Freely feeding rats received an anorexigenic dose of dl-fenfluramine HCl (5 mg/kg). Two hours following injection, their stomachs retained significantly greater dry weight contents than saline-injected controls. The same dose of fenfluramine decreased the rate of gastric emptying over a 2 h period to a similar extent in mildly food-deprived rats. The peripherally acting serotonin antagonist xylamidine counteracted the effect of fenfluramine in prolonging the satiating effect of an ad libitum meal of a given size. We propose therefore that the principal mechanism by which fenfluramine reduces food consumption in freely feeding rats is through a prolongation of the satiating effect of absorption as a result of slowing of gastric emptying, presumably via enhanced release of serotonin from nerve terminals in the wall of the gastrointestinal tract.

Amidines↗
PubMed1988

Effect of procaine injection into the ventromedial hypothalamic area (VMH) of the rat on serum insulin, glucose and corticosterone and gastric emptying rate.

Bilateral injection of procaine into the VMH resulted in a decrease in serum glucose and immunoreactive insulin levels in both food-deprived rats and meal-fed rats. Corticosterone levels and gastric emptying rate were unaffected by these VMH procaine injections. Since it is likely that the procaine disrupted only those neurons whose cell bodies and synapses lay in the region of the VMH, the results suggest that the two major factors in the etiology of the 'VMH syndrome' following electrolytic lesions, rapid emptying and insulin hyperresponsivity, are dependent upon destruction of fibers of passage through the VMH. Finally, the results further support the proposal that the VMH exerts tonic excitatory control over liver glucose output.

Animals↗
PubMed1988

Preferred sweetness of a lime drink and preference for sweet over non-sweet foods, related to sex and reported age and body weight.

The ideal sugar concentration in a lime drink, the tolerance of deviations from that ideal, the choices between sweet and non-sweet foods, and tea and coffee sugaring habits, were assessed for each individual in an unstratified sample of 344 children and adults of both sexes, and body mass index (BMI) for 241 of them. Lime drink ideal point, hot-drink sugaring habits and the preferences for cake trolley over cheeseboard, flavoured milk shake over ice-cold milk, lemonade or tonic water over soda water and bread and margarine with honey or chocolate spread over plain bread and margarine, were all reliably associated positively with each other. This confirms the reality of the "sweet tooth", but not its extension to all sweet foods, because preferences for carrot over celery and for orange juice over tomato juice were not reliably associated with the other preferences. On average, the men showed a greater sweetness preference than the women. Women and younger subjects showed on average greater preferences for carrot and orange juice over the alternatives. When BMI was disconfounded from age and sex, it did not relate either to the preference for foods and drinks generally regarded as sweet or to the preference for a sweet alternative to a non-sweet vegetable food or drink.

Adolescent↗
PubMed1988

Do comparisons of a food characteristic with ideal necessarily involve learning?

Untrained assessors graphically rated the saltiness of plain slices of white bread relative to a personally ideal level of saltiness, with each test session designed to minimize known contextual effects on ratings. Judgements were highly reliable from the first session. However, the mean of the residual variances of individuals' psychophysical functions was approximately halved by the fifth session. To test whether this was an accommodation to the method or to the product, assessors rated the same product by a different procedure in one further session and a different food by the same procedure in a final session. The mean residuals lay in the direction of an accommodation to the method, but this difference proved not to be significant. The initial fall in residuals might indicate some learning about the product which was not adequately tested in the experimental manipulation. Nevertheless, it is clear that the method can be immediately used with high precision by unpractised volunteers.

Adult↗
PubMed1988

Mechanisms from models--actual effects from real life: the zero-calorie drink-break option.

Animal and human laboratory models show that the suppression of appetite by a modest amount of readily assimilable energy, such as a caloric sweetener, is not likely to last longer than an hour. The transience of their satiating effect constitutes a mechanism whereby the sugars, starch, alcohol and fats in drinks and the snackfoods eaten with them could add to energy intake which is subsequently uncompensated and so contributes to weight gain. Conversely, if those in the habit of consuming such energy-containing drinks and accompaniments avoided such items or replaced them by low-calorie substitutes, this might help in weight reduction and even perhaps in prevention of obesity. The effectiveness of this "zero-calorie drink-break option" can be tested by correlating separately reported real-life eating habits and weight changes across people whose circumstances are similar. The existing field data indicate that the fatter a person is the more likely they are to use the conventional undifferentiated sugar-substitution strategies and also that these usually do not help weight reduction.

Appetite↗
PubMed1988

A simulation model of psychobiosocial theory of human food-intake controls.

Over 15 years ago, a psychobiosocial theory of appetite was formulated in the light of experimental evidence from rats and people that appetite was suppressed by the flow of energy to lean body mass and that much ingestion was a learned response to integrated dietary, somatic and social cues. Enough was known in 1973 about these influences on food intake and about rates of flow of energy-yielding substrates around the body of the rat to program a computer simulation which had no loose parameters. This rat model successfully predicted feeding patterns under a variety of normal and abnormal conditions, including the day-night meal rhythm, the overeating and obesity following ventromedial hypothalamic lesions, and the suppression of appetite by fenfluramine via slowed gastric emptying. In 1976, its parameter values were adjusted to those expected for an adult person having food freely available and a sedentary lifestyle. The output of this human model was remarkably realistic in meal pattern: culture appears to adapt to the physiological average. The predicted effect on appetite of energy released from adipose in proportion to the energy stored was relatively minute but very persistent. These old results are no less relevant now to improvement of our understanding of human food-intake controls and to more effective reduction and prevention of unhealthy overweight.

Appetite↗
PubMed1987

Salt and blood pressure: the triangular hypothesis.

If an unselected sample includes individuals whose blood pressure is sensitive to their salt intake and individuals whose blood pressure is not sensitive, then the superposition of these two sub-populations in a scatterplot of individuals' blood pressures against their salt intakes could give a triangular distribution. The non-correlation in the insensitives would obscure the correlation expected in the sensitives. This hypothesis justifies truncation of such data to test for correlation between blood pressure and salt intake among only the individuals in the higher range of blood pressures observed. No criterion of salt sensitivity is needed. The analysis should succeed if salt intake makes a major contribution to hypertension and would be improved if other putative causes were factored out.

Disease Susceptibility↗
PubMed1987

Effect of stimulus range on judgements of sweetness intensity in a lime drink.

The effect of the range of levels of the test stimuli on ratings of sweetness intensity is demonstrated for a lime drink. The results are consistent with Poulton's (1979) suggestion that range effects can be predicted from the deviation of the mean response in a session from the mid-point of the response dimension. It is demonstrated that this range bias can be avoided by adding a readily anchored mid-point (ideal) to the response dimension and selecting stimuli so that the mean response is close to this mid-point. This bias-reducing, relative-to-mid-point procedure also produces a stronger linear relationship between ratings and concentration ratios than does the conventional end-point-anchored intensity rating procedure. The similarity of the linear semi-log functions of response relative to extremely sweet and relative to ideally sweet is taken as evidence that the two types of responses are not independent.

Humans↗
PubMed1986

Effects of expanded tobacco on acceptability and reported consumption of low-tar cigarettes.

Experimental cigarettes designed for the low-tar band were made from one of two blends of tobacco and either 10% or 25% of expanded tobacco. They were smoked over a 7-day period by 24 habitual smokers of cigarettes in the middle-tar band. Sensory characteristics and acceptability of the cigarettes were assessed at first presentation, after 3 days and again at the end of the trial. The expanded-tobacco cigarettes were judged to be weaker than the smokers' own usual brands, and the 25% weaker than the 10% expanded. However, perceived strength increased over the 7-day trial. No effect of blend was detected. Smokers given cigarettes with 10% expanded tobacco smoked considerably more of them than was predicted from their reported normal consumption, but this sign of some compensation for reduced nicotine yield did not appear with 25% expanded tobacco. The implications are discussed for persisting smokers switching to the low-tar band, as officially advised to reduce health risks.

Adult↗