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PubMed2004

The C. elegans thermosensory neuron AFD responds to warming.

The mechanism of temperature sensation is far less understood than the sensory response to other environmental stimuli such as light, odor, and taste. Thermotaxis behavior in C. elegans requires the ability to discriminate temperature differences as small as approximately 0.05 degrees C and to memorize the previously cultivated temperature. The AFD neuron is the only major thermosensory neuron required for the thermotaxis behavior. Genetic analyses have revealed several signal transduction molecules that are required for the sensation and/or memory of temperature information in the AFD neuron, but its physiological properties, such as its ability to sense absolute temperature or temperature change, have been unclear. We show here that the AFD neuron responds to warming. Calcium concentration in the cell body of AFD neuron is increased transiently in response to warming, but not to absolute temperature or to cooling. The transient response requires the activity of the TAX-4 cGMP-gated cation channel, which plays an essential role in the function of the AFD neuron. Interestingly, the AFD neuron further responds to step-like warming above a threshold that is set by temperature memory. We suggest that C. elegans provides an ideal model to genetically and physiologically reveal the molecular mechanism for sensation and memory of temperature information.

Animals↗
PubMed2003

Novolizer: a multidose dry powder inhaler.

Novolizer is a multidose breath-actuated dry powder inhaler (DPI) approved for use with salbutamol (albuterol) and budesonide. It has multiple patient feedback mechanisms and an inspiratory flow rate threshold designed to optimise dosage. In two studies, children aged 4-11 years with asthma correctly used Novolizer and generated mean peak inspiratory flow rates (PIFRs) through Novolizer of 76 and 92.7 L/min, well above the Novolizer threshold of 35-50 L/min. In healthy volunteers, median lung deposition of budesonide administered via Novolizer was 19.9-32.1% at mean PIFRs of 54-99 L/min. In a randomised, double-blind, single-dose study in patients with chronic obstructive pulmonary disease (COPD) and asthma, the 1-hour improvement from baseline in mean maximum forced expiratory volume in 1 second (FEV(1)) was 21.3% with inhalation of salbutamol through Novolizer, and 19.5% through Sultanol pressurised metered-dose inhaler (MDI). FEV(1) increased significantly in patients with asthma and COPD treated for 4 weeks in a randomised, open-label comparison of salbutamol through either Novolizer or Sultanol MDI. A randomised open-label study in adults with asthma treated with inhaled budesonide found equivalent improvements in FEV(1) and symptoms with Novolizer and Turbuhaler. Novolizer was well accepted overall. Most patients preferred it to previously used MDIs or DPIs. Only 4-5% found the taste feedback unacceptable. Physicians observed improved compliance over 4 weeks in 80% of patients with asthma using Novolizer.

Administration, Inhalation↗
PubMed2000

Olfactory sensitivity and specificity of Arctic char, Salvelinus alpinus, to a putative male pheromone, prostaglandin f(2)alpha.

Actively spawning male Arctic char, Salvelinus alpinus, release immunoreactive F-prostaglandins into the water that attract ovulated females and elicit spawning behaviour. To investigate a possible role played by the olfactory system, we determined the sensitivity and specificity of the char to prostaglandins by the electro-olfactogram (EOG) using a newly devised stimulatory apparatus. Of 18 prostaglandins tested, PGF(2)alpha and two synthetic analogues, 16,16-dimethyl-PGF(2)alpha and U-46619, were detected at threshold concentrations of 0.5-1.0 x 10(-11) M, and at a concentration of 10(-8) M evoked an EOG response equivalent to that of 10(-5) M L-serine. Olfactory nerve twig recordings further demonstrated that the EOG responses were transduced into nerve impulses and transmitted to the brain. No difference was found in the responses between sexes and maturational stages. We conclude that PGF(2)alpha is a candidate of the male pheromone of Arctic char, supporting our previous behavioural studies.

Aging↗
PubMed1979

Gustatory responses of eel palatine receptors to amino acids and carboxylic acids.

The gustatory receptors of the eel palate were found to be extremely sensitive to amino acids and carboxylic acids. The results obtained are as follows: (a) 11 amino acids which are among naturally occurring amino acids elicited responses in the palatine nerve, but 9 amino acids did not elicit a response even at a high concentration. The effect of D-amino acids was always much less than that of their corresponding L-isomers. There was no appreciable difference in the effectiveness of an alpha-amino acid (alpha-alanine) and beta-amino acid (beta-alanine). (b) The threshold concentrations of the most potent amino acids (arginine, glycine) were between 10(-8) and 10(-9) M. A linear relation between the magnitude of the response and log stimulus concentration held for a wide concentration range for all the amino acids examined. (c) The palatine receptors responded sensitively to various carboxylic acid solutions whose pH was adjusted to neutral. The threshold concentrations varied between 10(-4) and 10(-7) M. The magnitude of the response at 10(-2) M increased with an increase of carbon chain length. (d) The extent of cross-adaptation was examined with various combinations of amino acids. A variety of the response patterns showing complete cross-adaptation, no cross-adaptation, or synergetic interaction was observed. The synergetic interaction was also observed when one amino acid below its threshold concentration was added to the other amino acid below its threshold concentration was added to the other amino acid. No cross-adaptation was observed between amino acids and fatty acids. (e) The treatment of the palate with papain led to loss of the responses to arginine, glycine, and histidine without affecting those to proline and acetic acid. The treatment with pronase E eliminated selectively the response to proline. The possibility that the eel gustatory receptors are responsible for sensing food at a distance was discussed.

Adaptation, Physiological↗
PubMedDate not supplied

Oxisterol determination in selected coffees.

The main aim of green-coffee processing techniques, such as decaffeination and roasting, is always to maintain a very high level of quality in taste and flavor, the beverage's most important characteristics to consumers. Oxidative alterations of coffee lipids, which can occur in roasting, exert a very marked influence on these quality traits. Determining the extent of oxidation thus can provide an indication of the product's potential shelf-life and reveal traces of any newly-formed oxidative products that might prove nutritionally unsafe. Yet, while much attention has recently been focused on certain by-products induced by cholesterol oxidation and their proven toxicity as risk factors in atherosclerosis and cancer, oxidated phytosterols have largely gone unnoticed, being considered along with beta-sitosterol as not very dangerous in that neither is absorbed by the intestinal tract. The present study investigates the substances derived from phytosterol oxidation (oxisterols) in samples of regular and decaffeinated commercial coffees. The findings show that oxisterols were absent in some samples and that the traces of oxidate phytosterols detected in others were well below the threshold considered as toxicologically active.

Coffee↗
PubMed1988

Preference differences for sucrose solutions in young and aged squirrel monkeys.

Licking patterns and molarity preferences, elicited by two sets of sucrose solutions (0.0 to 1.75 M and 1.0 to 3.0 M), were measured in six young and six aged squirrel monkeys. Sucrose preference thresholds were determined for each age group using sucrose concentrations from 0.025 to 0.1 M. Age was unrelated to sucrose preference thresholds. Consummatory activity of all monkeys increased monotonically as sucrose concentrations increased from 0.0 to 1.0 M. Aged, but not young, monkeys continued to increase consumption until sucrose concentrations exceeded 1.5 M. All monkeys increased consumption by increasing number of licks, number of licking bursts and total time spent licking. Unlike young monkeys, aged monkeys displayed high within animal variability of tongue contact times, exponentially decreasing rates of licking at high molarities, constant consumption efficiency decrements, and consistent negative correlations between tongue contact and following tongue off times.

Aging↗
PubMed1986

Auditory spaciousness: some further psychoacoustic analyses.

Psychoacoustic investigations have confirmed the known high correlation of auditory spaciousness and preference in concert-hall types of sound fields. Further, they have provided exploratory results which gave rise to the following interpretations: Auditory spaciousness is a multidimensional perceptual attribute, predominantly caused by early lateral reflections. Low-frequency reverberation may also contribute slightly, but is sensitive with respect to individual taste. All spectral components of early lateral reflections contribute to spaciousness. Spectral restriction of the reflections leads to less favorable judgments. Early lateral reflections which do not contain spectral components above about 3 kHz mainly create image expansion in the front-back direction, thus adding to the sense of envelopment of the listener. If components above about 3 kHz are present, image broadening is prominent. By means of a model of binaural signal processing which takes interaural arrival-time differences as well as interaural level differences into account, a quasiobjective measure of auditory spaciousness can be derived.

Adult↗
PubMed1995

Rapeseed meal-glucosinolates and their antinutritional effects. Part 6. Taint in end-products.

From the present review it is clear that glucosinolates and their breakdown products may pass in small amounts into such products as meat, milk or eggs without noticeable deterioration in their taste. When applying low glucosinolate rapeseed meal (LG-RSM) as the sole high protein component of concentrate mixture for cows, the level of rapeseed glucosinolates breakdown products should not exceed 0.1 mumol/l oxazolidinethione, 10 mumol/l unsaturated nitriles and 100 mumol/l thiocyanate. At these levels no evidence has been found to indicate the negative influence of glucosinolates breakdown products on the sensory properties of milk or threat for consumers. No published information appears to be available suggesting that glucosinolates have any deleterious effect on the carcass flavour in cattle. Even at a 20% inclusion of LG-RSM in diets no impairment on visual scores or sensory evaluation was found in pig's or broiler's carcass. Glucosinolated, chiefly progoitrin, which depress trimethylamine oxidation thus clearly affect the taint in eggs. In birds with genetically conditioned susceptibility (brown layers) fishy taint can be observed even at 0.3 microM progoitrin, i.e. approximately 0.5 microM total glucosinolates in 1 g diet. Assuming a threefold higher threshold for white layers (1 microM progoitrin in 1 g diet) fishy taint can be expected at a 10% LG-RSM level in diet, and only very low glucosinolate rapeseed meals can be fed to layers without the risk of fishy taint in eggs.

Animal Feed↗
PubMed2007

Quantitative structure-activity relationship study of bitter di- and tri-peptides including relationship with angiotensin I-converting enzyme inhibitory activity.

Bitterness represents a major challenge in industrial application of food protein hydrolysates or bioactive peptides and is a major factor that controls the flavor of formulated therapeutic products. The aim of this work was to apply quantitative structure-activity relationship modeling as a tool to determine the type and position of amino acids that contribute to bitterness of di- and tri-peptides. Datasets of bitter di- and tri-peptides were constructed using values from available literature, followed by modeling using partial least square (PLS) regression based on the three z-scores of 20 coded amino acids. Prediction models were validated using cross-validation and permutation tests. Results showed that a single-component model could explain 52 and 50% of the Y variance (bitterness threshold) of bitter di- and tri-peptides, respectively. Using PLS regression coefficients, it was determined that hydrophobic amino acids at the carboxyl-terminus and bulky amino acid residues adjacent to the carboxyl terminal are the major determinants of the intensity of bitterness of di- and tri-peptides. However, there was no significant (p > 0.05) correlation between bitterness of di- and tri-peptides and their angiotensin I-converting enzyme-inhibitory properties.

Amino Acid Sequence↗
PubMed2002

Distinctive neurophysiological properties of embryonic trigeminal and geniculate neurons in culture.

Neurons in trigeminal and geniculate ganglia extend neurites that share contiguous target tissue fields in the fungiform papillae and taste buds of the mammalian tongue and thereby have principal roles in lingual somatosensation and gustation. Although functional differentiation of these neurons is central to formation of lingual sensory circuits, there is little known about electrophysiological properties of developing trigeminal and geniculate ganglia or the extrinsic factors that might regulate neural development. We used whole cell recordings from embryonic day 16 rat ganglia, maintained in culture as explants for 3-10 days with neurotrophin support to characterize basic properties of trigeminal and geniculate neurons over time in vitro and in comparison to each other. Each ganglion was cultured with the neurotrophin that supports maximal neuron survival and that would be encountered by growing neurites at highest concentration in target fields. Resting membrane potential and time constant did not alter over days in culture, whereas membrane resistance decreased and capacitance increased in association with small increases in trigeminal and geniculate soma size. Small gradual differences in action potential properties were observed for both ganglion types, including an increase in threshold current to elicit an action potential and a decrease in duration and increase in rise and fall slopes so that action potentials became shorter and sharper with time in culture. Using a period of 5-8 days in culture when neural properties are generally stable, we compared trigeminal and geniculate ganglia and revealed major differences between these embryonic ganglia in passive membrane and action potential characteristics. Geniculate neurons had lower resting membrane potential and higher input resistance and smaller, shorter, and sharper action potentials with lower thresholds than trigeminal neurons. Whereas all trigeminal neurons produced a single action potential at threshold depolarization, 35% of geniculate neurons fired repetitively. Furthermore, all trigeminal neurons produced TTX-resistant action potentials, but geniculate action potentials were abolished in the presence of low concentrations of TTX. Both trigeminal and geniculate neurons had inflections on the falling phase of the action potential that were reduced in the presence of various pharmacological blockers of calcium channel activation. Use of nifedipine, omega-conotoxin-MVIIA and GVIA, and omega-agatoxin-TK indicated that currents through L-, N-, and P/Q- type calcium channels participate in the action potential inflection in embryonic trigeminal and geniculate neurons. The data on passive membrane, action potential, and ion channel characteristics demonstrate clear differences between trigeminal and geniculate ganglion neurons at an embryonic stage when target tissues are innervated but receptor organs have not developed or are still immature. Therefore these electrophysiological distinctions between embryonic ganglia are present before neural activity from differentiated receptive fields can influence functional phenotype.

Action Potentials↗
PubMed2001

Determination of key aroma compounds in the crumb of a three-stage sourdough rye bread by stable isotope dilution assays and sensory studies.

An investigation of the volatile fraction of a freshly prepared sourdough rye bread crumb by means of the aroma extract dilution analysis (AEDA), followed by identification experiments, revealed 22 flavor compounds in the flavor dilution (FD) factor range of 128 to 2048. Quantitations performed by stable isotope dilution assays (SIDA) and a calculation of odor activity values (OAV; ratio of concentration to odor threshold) revealed the following as contributors to the overall crumb flavor: 3-methylbutanal (malty), (E)-2-nonenal (green, fatty), (E,E)-2,4-decadienal (fatty, waxy), hexanal (green), acetic acid (sour, pungent), phenylacetaldehyde (honey-like), methional (boiled potato-like), vanillin (vanilla-like), 2,3-butandione (buttery), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (spicy), and 2- and 3-methylbutanoic acid (sweaty). Using either citrate buffer, starch, or deodorized crumb as model matrixes, the typical malty and sour rye bread crumb flavor was reproduced by adding a mixture of 20 reference odorants in the "natural" concentrations as quantitatively determined in the fresh crumb.

Bread↗
PubMed1999

Influence of variety and growing location on the development of off-flavor in precooked vacuum-packed potatoes.

Development of potato off-flavor (POF) was examined in precooked vacuum-packed potatoes by GC and sensory analyses. The experiments comprised four varieties grown at two locations. Aroma compounds shown to be potential contributors to POF were determined quantitatively, and their relative importance was interpreted by aroma values based on odor detection threshold values determined in water. There were statistically significant differences in the content of POF compounds between the growing locations and among some of the varieties. The results from the sensory analyses concurred roughly with the GC analyses. (E,E)-2,4-Nonadienal and (E, E)-2,4-decadienal were shown to be the most potent of the POF compounds examined, in addition with hexanal, (E)-2-octenal, and (E)-2-nonenal. Lowering the development of POF in precooked vacuum-packed potatoes should be possible by optimizing the environmental conditions and breeding for suitable varieties.

Aldehydes↗
PubMed1981

Sensory receptor sensitivity in autistic children: response times to proximal and distal stimulation.

On the basis of behavioral observation, it has been postulated that autistic children prefer proximal (touch, taste) to distal (sight, hearing) sensory modalities. To assess this systematically, autistic children's simple response times were measured with auditory, visual, and tactile stimulation. Children were studied for up to 25 sessions of 40 trials with each modality. Response times were significantly related to mental age. Autistic children's responses were significantly slower than normal children's. However, autistic children and normal children had the same pattern, fastest responding to auditory stimuli and slowest responding to tactile stimulation. Autistic children's preference for proximal stimuli probably reflects a continuation of immature behavior rather than a basic disturbance in sensory receptor sensitivity.

Adolescent↗
PubMed2006

Sensitivity to allyl isothiocyanate, dimethyl trisulfide, sinigrin, and cooked cauliflower consumption.

The consumption of cauliflower consumers has been related to the olfactory and gustatory sensitivities to potentially objectionable flavor compounds in this vegetable. Based on the ascending concentration series method of limits, a first experiment was designed to develop rapid tests dedicated to estimate individuals' olfactory thresholds for allyl isothiocyanate (AITC) and dimethyl trisulfide (DMTS) and gustatory thresholds for sinigrin (SIN). The best compromise between rapidity and reliability was obtained with two replications of a four-alternative forced choice (AFC) at six ascending concentrations (6x2x4-AFC) for both AITC and DMTS, and with a 6x1x4-AFC for SIN. In a second experiment, sensitivity to SIN, AITC and DMTS was determined on 267 participants divided into three cauliflower consumer target groups: non-, medium- or high consumers. The non-consumers were significantly more sensitive to SIN and AITC than were the medium and high consumers. No effect of consumer's sensitivity to DMTS was observed.

Adolescent↗
PubMed1982

High sensitivity of Xenopus gustatory receptors to amino acids and bitter substances.

The gustatory nerve responses of the aquatic toad Xenopus laevis to salts, acids, amino acids, and bitter substances were recorded. 1) The gustatory receptors were sensitive to amino acids and bitter substances. The thresholds were 10(-7) M for Arg, 3 X 10(-9) M for strychnine, and 3 X 10(-8) M for quinine, 200-20,000 times lower than the thresholds for the respective stimuli in the bullfrog. 2) The basic and the neutral amino acids were effective whereas the acidic ones were not. Relations between the responses and log stimulus concentrations for the basic amino acids were linear in a wide concentration range whereas those for the neutral ones were of S shape. Cross-adaptation did not occur among pairs of a basic amino acid and a neutral one. 3) Responses to the basic amino acids and the basic bitter substances were suppressed by the addition of salts to the stimulating solutions, while those to the neutral and the acidic substances were not suppressed.

Amino Acids↗
PubMed1988

D-1 and D-2 receptor antagonists decrease corn oil sham feeding in rats.

Intraperitoneal injection of the highly selective D-1 and D-2 receptor antagonists, SCH 23390 and (-)-raclopride, respectively, produced a dose-related decrease in the intake of corn oil in a 30-min, sham-feeding test. The threshold dose for a significant decrease in intake was 100 micrograms.kg-1 for SCH 23390 and 200 micrograms.kg-1 for raclopride. These doses did not impair rats' latencies to initiate sham feeding, and they did not produce any overt motor deficits. These data, therefore, are consistent with the hypothesis that central dopaminergic activity at both D-1 and D-2 receptors is necessary for the normal processing of the sensory and/or hedonic effects of the oral stimuli produced by corn oil during sham feeding.

Animals↗
PubMed1983

Central nervous system regulation of finicky feeding by the blowfly.

Finicky feeding refers to an animal's tendency to become more particular in accepting and choosing food as satiation is approached. We tested the hypothesis that finickiness in the blowfly is related to the balance between internal inhibition, generated by a full crop, and external sensory information, generated by oral chemoreceptor contact with food. Response thresholds to sucrose and sucrose/quinine mixtures were determined for blowflies at two different levels of food deprivation. The deterrent effect of a given quinine concentration on feeding depends upon the concentration of sucrose in the mixture and the animal's level of deprivation. Transection of the recurrent nerve that normally signals fullness of the crop releases central inhibition and leads satiated flies to accept higher concentrations of quinine mixed with sucrose than controls. The results of this study suggest that the central nervous system's set point for responding to sensory excitation by sugar, rather than sensitivity to quinine, peripheral or central, determines gustatory finickiness in the blowfly.

Animals↗
PubMedDate not supplied

Aging and information seeking: patterns in sampling of sucrose solutions.

This study intended to explore age-related strategies of information seeking and decision making, utilizing a content-free task. Better understanding of skills and motives of aged behavior might contribute to more effective intervention for their welfare. Young and old female participants were engaged in detecting the presence of sucrose in solutions of various concentrations. They also reported the number of samplings required for an affirmative or negative decision about each test solution. Compared to young people, the aged sampled more (repetitions) and had a higher detection threshold (intensity of stimulus), indicating higher requirements for information. It was assumed that the sampling curve would be bell-shaped and peak at the point of least certainty about the presence or absence of sucrose (probability of detection = 0.5). Such curve was observed only among the young females when the samplings across concentrations were pooled according to probability of detection. In the aged, the sampling curve was rather monotonic, indicating low utility and interchangeability of information resources. This was attributed to a preset sampling strategy, labeled as over-resourcing, considering the higher baseline and low utility. The implications of such strategy to experimental procedures and every day life were discussed.

Adult↗