Chemosensory Cross-Modal Stroop Effects: Congruent Odors Facilitate Taste Identification

In order to explore the cross-modal cognitive associations between smell and taste, a chemosensory analogue of the Stroop task (Stroop 1935) was developed. Fourteen participants were presented with an odorant and a tastant and asked to identify the tastant as "sweet" or "sour" by pressing 1 of 2 buttons as quickly as possible. Participants were faster to name the taste when it was presented with an odor that was congruent (e.g., strawberry/sweet) than with an incongruent odor (e.g., strawberry/sour). These results support the concept of a high level of cognitive integration between the senses of smell and taste and illustrates occasions of interference between information arising from different sensory systems.

Modern psychophysics and the assessment of human oral sensation

Psychophysical measures attempt to capture and compare subjective experiences objectively. In the chemical senses, these techniques have been instrumental in describing relationships between oral sensation and health risk, but they are often used incorrectly to make group comparisons. This chapter reviews contemporary methods of oral sensory assessment, with particular emphasis on suprathreshold scaling. We believe that these scales presently offer the most realistic picture of oral sensory function, but only when they are used correctly. Using converging methods from psychophysics, anatomy, and genetics, we demonstrate valid uses of modern chemosensory testing in clinical diagnosis and intervention.

Odor/taste integration and the perception of flavor

Perceptions of the flavors of foods or beverages reflect information derived from multiple sensory afferents, including gustatory, olfactory, and somatosensory fibers. Although flavor perception therefore arises from the central integration of multiple sensory inputs, it is possible to distinguish the different modalities contributing to flavor, especially when attention is drawn to particular sensory characteristics. Nevertheless, our experiences of the flavor of a food or beverage are also simultaneously of an overall unitary perception. Research aimed at understanding the mechanisms behind this integrated flavor perception is, for the most part, relatively recent. However, psychophysical, neuroimaging and neurophysiological studies on cross-modal sensory interactions involved in flavor perception have started to provide an understanding of the integrated activity of sensory systems that generate such unitary perceptions, and hence the mechanisms by which these signals are "functionally united when anatomically separated". Here we review this recent research on odor/taste integration, and propose a model of flavor processing that depends on prior experience with the particular combination of sensory inputs, temporal and spatial concurrence, and attentional allocation. We propose that flavor perception depends upon neural processes occurring in chemosensory regions of the brain, including the anterior insula, frontal operculum, orbitofrontal cortex and anterior cingulate cortex, as well as upon the interaction of this chemosensory "flavor network" with other heteromodal regions including the posterior parietal cortex and possibly the ventral lateral prefrontal cortex.

Odor/taste integration and the perception of flavor

Perceptions of the flavors of foods or beverages reflect information derived from multiple sensory afferents, including gustatory, olfactory, and somatosensory fibers. Although flavor perception therefore arises from the central integration of multiple sensory inputs, it is possible to distinguish the different modalities contributing to flavor, especially when attention is drawn to particular sensory characteristics. Nevertheless, our experiences of the flavor of a food or beverage are also simultaneously of an overall unitary perception. Research aimed at understanding the mechanisms behind this integrated flavor perception is, for the most part, relatively recent. However, psychophysical, neuroimaging and neurophysiological studies on cross-modal sensory interactions involved in flavor perception have started to provide an understanding of the integrated activity of sensory systems that generate such unitary perceptions, and hence the mechanisms by which these signals are "functionally united when anatomically separated". Here we review this recent research on odor/taste integration, and propose a model of flavor processing that depends on prior experience with the particular combination of sensory inputs, temporal and spatial concurrence, and attentional allocation. We propose that flavor perception depends upon neural processes occurring in chemosensory regions of the brain, including the anterior insula, frontal operculum, orbitofrontal cortex and anterior cingulate cortex, as well as upon the interaction of this chemosensory "flavor network" with other heteromodal regions including the posterior parietal cortex and possibly the ventral lateral prefrontal cortex.

Response of the tendon during limb lengthening

Little is known about the increase in length of tendons in postnatal life or of their response to limb lengthening procedures. A study was carried out in ten young and nine adult rabbits in which the tibia was lengthened by 20% at two rates 0.8 mm/day and 1.6 mm/day. The tendon of the flexor digitorum longus (FDL) muscle showed a significant increase in length in response to lengthening of the tibia. The young rabbits exhibited a significantly higher increase in length in the FDL tendon compared with the adults. There was no difference in the amount of lengthening of the FDL tendon at the different rates. Of the increase in length which occurred, 77% was in the proximal half of the tendon. This investigation demonstrated that tendons have the ability to lengthen during limb distraction. This occurred to a greater extent in the young who showed a higher proliferative response, suggesting that there may be less need for formal tendon lengthening in young children.

Responses of PROP taster groups to variations in sensory qualities within foods and beverages

Despite increasing evidence that variations in sensitivity to the bitterness of 6-n-propylthiouracil (PROP) are also reflected in responses to other tastes in solution, there has been little research examining the impact of PROP sensitivity on responses to sensory qualities in foods or beverages. The present studies examined responses of PROP taster groups to systematic variations in tastes and oral irritation in different foods and beverages. In Experiment 1, PROP groups were asked to discriminate variations in bitterness, sweetness, or sourness within two foods (yogurt and cream cheese) and a beverage (orange juice). In most cases, tasters and especially supertasters (STs) were able to discriminate smaller variations in tastant concentration than PROP nontasters (NTs). Differences were most evident with variations in bitterness and sourness. In Experiment 2, PROP taster groups rated the sweetness, sourness, and oral irritation in carbonated fruit drinks that systematically varied in citric acid (CA) and CO2 concentrations. Ratings of sourness and irritation were highest for STs and lowest for NTs, although there were no group differences for sweetness ratings. These data are some of the first to show PROP taster group differences in tastes and irritation within foods and provide a basis for reported differences of PROP groups in their hedonic responses to foods.

Oncogene-dependent tumor suppression: using the dark side of the force for cancer therapy

Cancers arise by an evolutionary process that involves the protracted acquisition by somatic cells of suites of interlocking mutations that uncouple proliferation, survival, migration, and damage responses from the mechanisms (selective pressures) that normally restrain or restrict them in time and space. The relative rareness of cancer cells within the soma, in the face of huge numbers of available cell targets, substantial rates of mutation, and an abundance of proto-oncogenes and tumor suppressor gene targets, indicates that the evolutionary space available to incipient tumor cells is highly restricted. The principal way in which this is achieved is through intrinsic tumor suppression pathways-innate growth arrest and apoptotic programs that fulfill an essentially analogous functional role to checkpoints in the cell cycle machinery by antagonizing the tumorigenic potential of oncogenic mutations. Using switchable transgenic and knockin mouse models, it is possible to identify these various tumor suppressor programs and establish where, when, how, and why they act to forestall neoplasia in each tissue type and, consequently, how and why their failure leads to cancer.

Incidental Learning and Memory for Three Basic Tastes in Food

Forty three subjects were invited under the pretence that they would take part in an experiment on hunger feelings. They came without having eaten anything that morning and received a standard breakfast containing orange juice, cream cheese on crackers and yoghurt. These products were later (when subjects returned after scoring hunger feelings during the day) used as targets amidst a set of distractors varied by adding or subtracting different amounts of two basic tastes. Orange juice was varied in sweetness and bitterness, cream cheese in sourness and bitterness and yoghurt in sweetness and sourness. The changes were made comparable by using just noticeable differences, determined in preliminary experiments with other subjects, as units of change. Two measurements of memory were compared, an absolute (indicating which were the targets) and a relative one (indicating whether the targets and distractors were more, less or equally pleasant, sweet, sour, bitter or salty as the item eaten at breakfast). Both methods showed incidental learning, but relative memory was superior. Memory differed between tastes and was partly product dependent. These experiments suggest that taste memory is tuned to detect novel and potentially dangerous stimuli rather than to remember features of earlier experienced stimuli with great precision.

Effects of added glutamate on liking for novel food flavors

Adding glutamate to foods increases their umami quality, their acceptability and their consumption. The functional significance of this palatability is unclear. Other highly palatable substances, e.g. sugar and fats, also increase liking for novel flavors with which they are repeatedly paired, especially when ingested. This is thought to reflect the rewarding effects of sugar and fat energy, post-ingestion. To determine if a liking for novel flavors can also be conditioned using glutamate, 44 subjects rated 10 ml samples of three novel soups for liking and familiarity, both before and after seven daily exposures to each of two soup flavors-one with added monosodium l-glutamate (MSG) (0.5% w/w; MSG+) and one without (MSG-). During exposure, subjects received either a 250 ml bowl of soup (Consume group) or a 10 ml sample (Taste group). There were no significant differences as a function of samples or groups, despite some trends for changes in liking to be higher in the consumed MSG+ condition. In a second experiment, 69 subjects were divided into three groups (Consume MSG+; Consume MSG-; Taste MSG+) in which they received nine exposures to one novel soup flavor. The Consume MSG+ group showed a significantly greater increase in liking than either the Consume MSG- or the Taste MSG+ groups, which did not differ. Changes in familiarity ratings reflected amount consumed, not MSG content. Pairing glutamate with a novel flavor can condition liking for that flavor. While post-ingestive effects of glutamate may be rewarding, flavor conditioning cannot be ruled out.

Odor-Taste Interactions: Effects of Attentional Strategies during Exposure

Through repeated pairings with a tastant such as sucrose, odors are able to take on the tastant's qualities, e.g. by becoming more sweet smelling. When such odors are subsequently experienced with a sweet tastant in solution, the mixture is often given a higher sweetness rating than the tastant alone. Odor-induced taste enhancement appears to be sensitive to whether an odor-taste combination is viewed analytically as a set of discrete qualities, or synthetically as a flavor. The present research attempted to determine if adoption of these different perceptual approaches during co-exposure with sucrose would influence the extent to which an odor would become sweet smelling and subsequently enhance sweetness intensity. In Experiment 1, subjects received multiple exposures to mixtures of sucrose with low sweetness, low familiarity odors or, as a control, the odors and sucrose solutions separately. Two groups that received mixtures made intensity ratings that promoted either synthesis or analysis of the individual elements in the mixtures. The odors became sweeter smelling irrespective of group. Only adopting a synthetic strategy produced odors that enhanced sweetness in solution. However, these effects were also shown with a 'non-exposed' control odor. This could be accounted for if the single co-exposure with sucrose that all odors received in the pre-test was able to produce sweeter odors. A second experiment confirmed this prediction. Thus, while even a single co-exposure with sucrose is sufficient to produce a sweeter odor, the adoption of a synthetic perceptual strategy during the co-exposure is necessary to produce an odor that will enhance sweetness. These data are consistent with associative leaning accounts of how odors take on taste qualities and also support the interpretation that these effects reflect the central integration of odors and tastes into flavors.

Molecular manifestations and molecular determinants of telomere capping

Multiple interacting components of the telomere, together with telomerase (and sometimes recombination), determine whether a telomere will be functional, allowing cell proliferation. The various components reinforce each other, providing for a robust and resilient system of protection and replenishment of telomeres. A characteristic of a telomere is that its structural features elicit responses that allow it to be dynamically recapped. Eliciting a DNA damage response through uncapping of a telomere appears to be one way in which telomerase action at that telomere is stimulated. Thus, as long as a timely and appropriate recapping of the telomere is possible, regulated uncapping of a telomere appears to be not only normal, but even required for optimal telomere maintenance. Telomere length and the presence of telomerase provide an example of a pair of interacting components that determine telomere capping function. Telomerase is dispensable in cells with sufficiently long telomeres; but in cells with short telomeres lacking telomerase, cells lose the ability to proliferate, and in some cell types, telomere fusions are increased. However, expressing telomerase can make even very short telomeres functional. Many interesting questions remain as to the mechanisms of these biological effects.

A one-quarter reduction in the salt content of bread can be made without detection

OBJECTIVE

To determine if it is possible to deliver a one-quarter reduction in the sodium content of bread without detection.

DESIGN

Single-blind, randomized, controlled trial.

SETTING

The Royal North Shore Hospital in Sydney, Australia.

PARTICIPANTS

One-hundred and ten volunteers from the hospital staff that completed 94% of scheduled assessments.

INTERVENTION

Six consecutive weeks of bread with usual sodium content or six consecutive weeks of bread with cumulating 5% reductions in sodium content each week.

MAIN OUTCOME MEASURE

The proportion of participants reporting a difference in the salt content of the study bread from week to week.

RESULTS

The intervention group were no more likely than the control group to report a difference in the salt content of the bread from week to week (P=0.8). Similarly, there were no differences between randomized groups in the scores for flavour (P=0.08) or liking of the bread (P=0.95) over the study follow-up period. However, the saltiness scores recorded on a visual analogue scale did decline in the intervention group compared with the control group (P=0.01)

CONCLUSIONS

A one-quarter reduction in the sodium content of white bread can be delivered over a short time period, while maintaining consumer acceptance. Over the long term, and particularly if achieved for multiple foods, a decrease in sodium content of this magnitude would be expected to reduce population levels of blood pressure and the risks of stroke and heart attack.

Does information about MSG (monosodium glutamate) content influence consumer ratings of soups with and without added MSG?

Responses to recent concerns about perceived adverse health effects of monosodium glutamate (MSG) have included using prominent labels, e.g., "No added MSG", on products. Label information has been shown to create expectations for a food's sensory properties and acceptability, and influence evaluations of the product. To assess the impact of information about MSG content, subjects evaluated saltiness, richness, natural taste of, and liking for, vegetable soups with (MSG+) and without (MSG-) added MSG. Their attitudes to MSG were evaluated and found to be generally negative. Subjects tasted both soups under three information conditions, presented as an ingredient list: contains added MSG, does not contain added MSG, or no mention of MSG. The expected changes in liking and sensory properties due to added MSG were found, but there were no effects of information. A second experiment used a more obvious manipulation of information on added MSG content, as well as two soup flavors to reduce the obvious differences between the MSG+ and MSG- soups. Again, there were no effects of information. These data suggest that sensory properties are weighted more than information when products are evaluated during tasting, even when the information is highly relevant to beliefs and attitudes.

A comparison of the nutritional value, sensory qualities, and food safety of organically and conventionally produced foods

Given the significant increase in consumer interest in organic food products, there is a need to determine to what extent there is a scientific basis for claims made for organic produce. Studies comparing foods derived from organic and conventional growing systems were assessed for three key areas: nutritional value, sensory quality, and food safety. It is evident from this assessment that there are few well-controlled studies that are capable of making a valid comparison. With the possible exception of nitrate content, there is no strong evidence that organic and conventional foods differ in concentrations of various nutrients. Considerations of the impact of organic growing systems on nutrient bioavailability and nonnutrient components have received little attention and are important directions for future research. While there are reports indicating that organic and conventional fruits and vegetables may differ on a variety of sensory qualities, the findings are inconsistent. In future studies, the possibility that typical organic distribution or harvesting systems may deliver products differing in freshness or maturity should be evaluated. There is no evidence that organic foods may be more susceptible to microbiological contamination than conventional foods. While it is likely that organically grown foods are lower in pesticide residues, there has been very little documentation of residue levels.

Binary taste mixture interactions in prop non-tasters, medium-tasters and super-tasters

It is generally assumed that the mutual, but asymmetric, suppression of the components in binary taste mixtures is an invariant property of the human psychophysical response to such mixtures. However, taste intensities have been shown to vary as a function of individual differences in sensitivity, indexed by the perceived bitterness of 6-n-propylthiouracil (PROP). To determine if these variations in taste perception influence taste mixture interactions, groups of PROP super-, medium- and non-tasters assessed four binary taste mixtures: sweet-bitter [sucrose/quinine hydrochloride (QHCl)], sweet-sour (sucrose/citric acid), salty-bitter (NaCl/QHCl) and salty-sour (NaCl/citric acid). In each experiment, subjects received factorial combinations of four levels of each of two tastants and rated individual taste intensities and overall mixture intensity. For each taste quality, super-tasters typically gave higher ratings than either medium- or non-tasters, who tended not to differ. There were also group differences in the interactions of the mixtures' components. Super-tasters rated the overall intensity of the mixtures, most likely reflecting integration of the taste components, as greater than medium- and non-tasters, who again showed few differences. In sweet-bitter mixtures, non-tasters failed to show the suppression of sweetness intensity by the highest QHCl concentration that was evident in super- and medium-tasters. These data show that the perception of both tastes and binary taste mixture interactions varies as a function of PROP taster status, but that this may only be evident when three taster groups are clearly distinguished from one another.

Altering telomere structure allows telomerase to act in yeast lacking ATM kinases

BACKGROUND

Telomerase is a ribonucleoprotein that copies a short RNA template into telomeric DNA, maintaining eukaryotic chromosome ends and preventing replicative senescence. Telomeres differentiate chromosome ends from DNA double-stranded breaks. Nevertheless, the DNA damage-responsive ATM kinases Tel1p and Mec1p are required for normal telomere maintenance in Saccharomyces cerevisiae. We tested whether the ATM kinases are required for telomerase enzyme activity or whether it is their action on the telomere that allows telomeric DNA synthesis.

RESULTS

Cells lacking Tel1p and Mec1p had wild-type levels of telomerase activity in vitro. Furthermore, altering telomere structure in three different ways showed that telomerase can function in ATM kinase-deleted cells: tel1 mec1 cells senesced more slowly than tel1 mec1 cells that also lacked TLC1, which encodes telomerase RNA, suggesting that tel1 mec1 cells have residual telomerase function; deleting the telomere-associated proteins Rif1p and Rif2p in tel1 mec1 cells prevented senescence; we isolated a point mutation in the telomerase RNA template domain (tlc1-476A) that altered telomeric DNA sequences, causing uncontrolled telomeric DNA elongation and increasing single strandedness. In tel1 mec1 cells, tlc1-476A telomerase was also capable of uncontrolled synthesis, but only after telomeres had shortened for >30 generations.

CONCLUSION

Our results show that, without Tel1p and Mec1p, telomerase is still active and can act in vivo when the telomere structure is disrupted by various means. Hence, a primary function of the ATM-family kinases in telomere maintenance is to act on the substrate of telomerase, the telomere, rather than to activate the enzymatic activity of telomerase.

Coprescribing proton pump inhibitors with other medications

Proton pump inhibitors, the treatment of choice for acid-related disorders, are often coadministered with other medications, sometimes with potentially adverse interactions. Although all agents studied may potentially interact with one proton pump inhibitor or another, a literature review documented adverse interactions for 10 medications in particular. Furthermore, 44% of people using proton pump inhibitors received another gastrointestinal drug. Although documented interactions involving these agents have been reported infrequently, the authors advise that physicians and pharmacists should recognize this possibility and watch for potentially problematic combination therapy.