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Smell and taste function in subjects with chronic obstructive pulmonary disease. Effect of long-term oxygen via nasal cannulas.

It was hypothesized that subjects with chronic obstructive pulmonary disease (COPD) receiving long-term oxygen via nasal cannulas have an impaired sense of smell and/or taste. To objectively evaluate the sense of smell and taste, this study used the University of Pennsylvania Identification Test (UPSIT), a 40-item "scratch-n-sniff" test and a 20-item taste test using the four basic taste sensations of sweet, salt, sour, and bitter. Twenty subjects (15 male, 5 female) with severe COPD receiving long-term oxygen therapy (group 1), and an equal number of age- and sex-matched subjects with COPD not receiving oxygen therapy (group 2), and a healthy control group (group 3) were studied. Twelve subjects (seven male, five female) from group 1 subsequently underwent transtracheal oxygen catheter installation. Mean +/- SD for the basic smell test was significantly greater in group 3 (35.35 +/- 3.58) as compared with group 1 (27.70 +/- 6.07) or group 2 (31.10 +/- 4.95) (p less than 0.005). The difference between group 1 and 2 was not significant (p = 0.066). However, when adjusted for pack years of smoking, there were no significant differences between the three groups. Mean +/- SD correct responses for the basic taste test were significantly greater in group 3 (15.75 +/- 1.81) as compared with group 2 (12.8 +/- 2.78) (p less than 0.005) and group 1 (14.00 +/- 2.33) (p less than 0.05). There was no significant difference between group 1 and 2. The corrected data for taste, adjusted for years since quitting smoking, did not alter the basic differences between the groups. Mean smell and taste test scores were essentially unchanged in 12 subjects after six months of transtracheal oxygen therapy. Long-term oxygen use via nasal cannulas in this group of subjects with COPD did not appear to impair their sense of smell and taste. Smoking had a significant but variable effect on the sense of smell and taste.

Female↗

Role of monoamines in afferent synaptic transmission in frog taste organ.

To examine physiological and pharmacological characteristics of synaptic transmission from taste cells to afferent nerve terminals in frog taste organ, changes in the glossopharyngeal nerve discharges and responses to chemical stimulation of the tongue were examined by intra-arterially perfusing the tongue with Ringer solution containing monoamines and their related substances. Noradrenaline (NA), dopamine (DA), and adrenaline (AD) produced an increase in the spontaneous glossopharyngeal nerve discharges as well as an enhancement of taste responses to various kinds of chemical stimuli, but they did not affect tactile response. NA was the most effective of the three. Monoamine-releasing agents, tyramine and 6OHDA, enhanced spontaneous nerve discharges but depressed taste responses. Antimonoaminergic agents, phentolamine and phenoxybenzamine (alpha-blockers), increased nerve discharges and depressed taste responses, but did not affect tactile response. DCI (beta-blocker), except at high concentrations, affected neither nerve discharges nor taste responses. Pre-treatment of frogs with monoamine-depleting agents, alpha-MPT and 6OHDA, depressed taste responses. Reserpine enhanced the effect of alpha-MPT. The depressed taste responses recovered after perfusion of the tongue with NA. From the results obtained, the possibility of NA being a transmitter at the afferent synapse in the frog taste organ was discussed.

Action Potentials↗

Ontogeny of taste sense.

Developmental changes in the taste receptors and CNS, in physiological and behavioural patterns in fetus and postnatal animals constitute the ontogeny of taste. Tongue epithelial cells are modified into taste buds only with innervation and are seen to degenerate on denervation. On removal of a portion of the tongue, with its taste buds, the central projections of gustation also atrophy, indicating an interdependence of taste receptors and central areas for their development. Gradual transitions in electrical responses to taste stimuli are shown from fetal to adult stage. While responses to ammonium chloride are marked in early fetus, with advancements in age responses to a wide variety of chemicals are shown. Again, early in the development, fibers responsive to chloride are predominant while at a later stage fibers responsive to sodium increase in number. Behaviourally, human fetus and neonatal mammals showed increased swallowing movements on sweet taste and decreased movements on bitter taste which is somewhat at variance with electrophysiological evidence and reflects on the multimodal involvement of taste cell functional and behavioural dynamics with age.

Animals↗

Taste changes experienced by patients receiving chemotherapy.

PURPOSE/OBJECTIVES: To increase knowledge about the nature, frequency, and quality-of-life (QOL) effects associated with taste changes after chemotherapy. DESIGN: Cross-sectional, descriptive. SETTING: 11 outpatient urban and suburban oncology centers. SAMPLE: 284 adults who had received at least two chemotherapy cycles. METHODS: Patients completed a taste change questionnaire and the Functional Assessment of Cancer Therapy-General, and nurses collected demographic and disease-related information. Descriptive statistics, Spearman correlations, chi-square, Mann-Whitney, and Kruskal-Wallis one-way analysis of variance were calculated. FINDINGS: Taste changes were frequent and at least moderately severe for many patients, who often reported dry mouth, decreased appetite, nausea, and vomiting. Cisplatin and doxorubicin were the agents most likely to be related to severe taste changes and to have caused greater distress from taste changes, which also were associated with decreased QOL. Oncology nurses and physicians rarely discussed taste changes with patients, who often tried changing the ways they seasoned their food. CONCLUSIONS: Taste changes are a frequent and significant problem for patients receiving chemotherapy and have negative effects on patients' QOL. Oncology nurses and physicians typically do not offer self-management suggestions to patients. IMPLICATIONS FOR NURSING RESEARCH AND PRACTICE: Repeated-measures research may provide a clearer understanding of chemotherapy-associated taste changes over time. Studies to examine strategies suggested from this and other research as well as clinical literature may determine which self-care interventions are most useful. Nurses should inform patients that taste changes may occur following chemotherapy, provide self-management information, and assess for related problems that could increase chemotherapy morbidity.

Adult↗

The pilot trial of the prevention of the increase in electrical taste thresholds by zinc containing fluid infusion during chemotherapy to treat primary lung cancer.

It is well known that there are various adverse effects during chemotherapy for cancer treatment. A taste disorder is also seen in 35-70% of patients. It has been reported that a zinc deficiency is associated with the development of these alterations in taste sensation. The purpose of this pilot study was to determine whether the zinc including infusion had the effect on taste disorder in patients with lung cancer. Taste disorder was evaluated as the increase in electrical taste thresholds using an electrogustometer. The plasma zinc concentration was also measured. Although there was no significant correlation, the increase in taste thresholds was detected in many patients who had a low zinc concentration even before receiving chemotherapy. Moreover, after 2 weeks of chemotherapy, almost all patients who did not have a zinc containing infusion showed development of taste disorder (5/5, 100% at chorda tympani area; 4/5, 80% at glossopharyngeal area), whereas no development of taste disorder was observed in those patients receiving a zinc containing infusion. These results suggest the possibility that the administration of zinc during chemotherapy could be a useful supportive therapy for preventing taste disorder and to help maintain a better quality of life.

Aged↗

Comparison of high-pressure freezing/freeze substitution and chemical fixation of catfish barbel taste buds.

The barbel taste buds of catfish are widely used as a model system for investigating the structure and function of vertebrate taste buds. We have examined the ultrastructure of the taste buds of the channel catfish, Ictalurus punctatus, as part of a comparative study of the morphology of taste buds in various mammalian and non-mammalian vertebrates. Since conventional chemical fixation methods have limited usefulness for certain kinds of ultrastructural studies (i.e., localization of diffusible substances or labeling techniques requiring retention of biological activity), we have developed methods for fixing catfish barbel taste buds by high-pressure freezing followed by freeze-substitution (HPF/FS) and have compared the ultrastructure of taste buds fixed by this technique and by chemical fixation procedures. The morphological details of the cells within taste buds are significantly affected by the method of fixation employed. In general, membrane contours are smoother and intracellular organelles more regular in shape in HPF/FS samples as compared with the chemically fixed specimens. Absolute and relative electron-densities of various tissue components are also affected by the fixation method employed. Certain ultrastructural features are more clearly visualized by one or the other of the fixation procedures. Fixation of barbel taste buds by HPF/FS not only provides an alternative view of the ultrastructure of taste bud cells but also offers a method of tissue preparation that may prove to be preferable to chemical methods for ultrastructural investigations involving procedures such as immunohistochemical labeling.

Animals↗

Porcine lingual taste buds: a quantitative study.

BACKGROUND: Taste buds on the pig tongue have been neither studied in detail nor quantified. We have counted the numbers of fungiform and vallate papillae, estimated their taste bud densities, and computed numbers of taste buds per volume of papilla on porcine tongue. Pig was chosen for this work because it is an omnivorous animal, and is one of the better models for study of nutrition-related problems in omnivorous human beings. METHODS: Tongues from three adult pigs were obtained from the local abattoir, fixed in 10% neutral buffered formalin, and mapped for the fungiform and vallate papillae. Serial 15 microns sections were prepared from blocks containing the papillae, and were stained by H & E. Density and volume of the taste buds were estimated using a Bioquant system. RESULTS: Eight hundred fifty and 826 fungiform papillae were observed on tongue I and II, respectively; numerically vallate papillae were 1, 2, and 2 for tongue I, II and III, respectively. Number of taste buds per fungiform papilla was considerably less on the dorsal surface of the tongue (3.88/papilla) than on the lateral side (22.11/papilla). Vallate papillae contained significantly more taste buds, a mean of 732.67 per papilla (t = 14.27; df = 6; P = < 0.05), than in the fungiform papillae. Density of the buds per volume of fungiform papilla was notably less on the dorsum (13.69) than on the lateral border (30.08). The density of vallate papillae taste buds per volume of the papilla was significantly greater than the lateral and dorsal papillae taste bud density (t = 4.28; df = 6; P < or = 0.05). CONCLUSIONS: The present results are relevant to studies on variations of taste sensitivity among regions of the tongue.

Animals↗

Role of apical ion channels in sour taste transduction.

Sour taste perception depends primarily on the concentration of H+ in the taste stimulus. Acid stimuli elicit concentration-dependent action potentials in taste cells. Recent patch-clamp studies suggest that protons depolarize taste cells by direct interaction with apically located ion channels. In Necturus maculosus, the voltage-dependent K+ conductance is restricted to the apical membrane of taste cells. The current flows through a variety of K+ channels with unitary conductances ranging from 30 to 175 pS, all of which are blocked directly by citric acid applied to outside-out or perfused cell-attached patches. In contrast, hamster fungiform taste cells appear to utilize the amiloride-sensitive Na+ channel for acid transduction. Amiloride completely inhibits H+ currents elicited by acid stimuli in isolated taste cells, with an inhibition constant similar to that for amiloride-sensitive Na+ currents (Ki = 0.2 microM). Treatment of isolated taste cells with the bioactive peptide arginine-vasopressin results in similar increases in both the amiloride-sensitive Na+ and H+ currents; the effect is mimicked by 8-bromocyclic AMP. These results suggest that H+ can permeate amiloride-sensitive Na+ channels in hamster fungiform taste cells, contributing to the transduction of sour stimuli.

Animals↗

Genetic and pathological taste variation: what can we learn from animal models and human disease?

The study of patients with taste disorders (i.e. 'experiments of nature') suggests that the old tongue maps (e.g. sweet on the tip, bitter on the back) that often appear in textbooks are wrong. If they were correct, severing the taste nerves that innervate the front of the tongue would result in a loss of the ability to taste sweet, etc. This does not occur. Severing these nerves has little effect on everyday taste experience because taste nerves inhibit one another. Damaging one nerve abolishes its ability to inhibit others and the release-of-inhibition compensates for the damage. There is sometimes a clinical cost for this redundancy; release-of-inhibition can produce taste phantoms. Genetic variation in taste ability occurs across and within species. For example, about 25% of humans are relatively unresponsive to a variety of sweet and bitter compounds (non-tasters) while another 25% are unusually responsive (supertasters). Supertasters have about four times as many taste buds as non-tasters and have smaller and more densely packed fungiform papillae. Since there are pain fibres associated with taste buds, supertasters are unusually responsive to the oral burn of spices.

Animals↗

Age does not affect numbers of taste buds and papillae in adult rhesus monkeys.

Taste buds and papillae in tongues of rhesus monkeys were examined and counted to determine if there are age-related differences in general morphology or numbers of receptor organs. Tongues from 15 monkeys in five groups aged 4-31 years were studied with light microscopy. Fungiform, circumvallate, and foliate papillae were examined and taste buds in each papilla type were counted. Numbers of papillae did not differ with age through 31 years; however, at 24 years and older, fungiform papillae were reduced in number in some animals that had lost tongue tips due to trauma. There were no age-related differences in numbers of taste buds in any of the three gustatory papilla types, nor did taste bud diameter alter with age. From data on each papilla type, estimates were made of total numbers of lingual taste buds. Totals ranged from about 8,000 to 10,000 and there were no age-related differences. These results support other recent reports that taste buds are not decreased in number in old rats or humans. Since taste bud numbers and general morphology are maintained even in old age, any age-related differences in taste behavior cannot be attributed to gross degenerative changes in lingual taste buds.

Aging↗

Immunohistochemical observation on substance P in regenerating taste buds of the rat.

The present study was performed to investigate the relationship between substance P-positive (SP-positive) nerve fibers and regeneration of taste buds in the foliate papillae of the rat by means of immunohistochemistry. It was confirmed by neurotomy that taste buds in the foliate papillae of the rat were innervated mostly (90%) by the glossopharyngeal (IXth) nerve and partly (10%) by the chorda tympani. In this experiment, the IXth nerve was sectioned distal to the petrosal ganglion. The rats were sacrificed at various intervals from 20 days to 80 days after the operation. In the course of degeneration and disappearance of taste buds, both SP-positive fibers and taste buds disappeared completely from the posterior folds of the foliate papillae 7 days after the operation. Within 22 days, regenerated SP-positive fibers began to appear in the lamina propria, and following the penetration of the fibers into the epithelium, taste bud anlagen reappeared at the bottom of the trench, and in the posterior folds at 24 days. The process of new taste bud formation extended toward the apex of the trench and to the anterior folds, which seemed to follow the regeneration in the nerve trunk. Quantitative data showed a gradual increase in the number of taste buds and taste buds containing SP-positive fibers. These findings indicate that SP might have a role in regeneration of taste buds.

Animals↗

Taste bud development in the channel catfish.

Taste bud formation in channel catfish is first seen to occur in stage 39 embryos, when taste bud primordia (stage 1), consisting of three to five cells, including a single calretinin-positive cell, can be recognized within the oropharyngeal cavity and maxillary barbels. Within a short time (stage 40), stage 2 taste bud primordia are apparent and include two or three calretinin-positive cells. The number of calretinin-positive cells continues to increase (stage 3), and the primordia begin to erupt as mature taste buds (stage 4) by embryonic stage 48. This same pattern of taste bud development characterizes other regions of the head, with calretinin-positive cells first detected around the mouth and on the other barbels by stage 41 and on the rest of the head by stage 48. The development of trunk taste buds lags far behind that of the head, with the first calretinin-positive cells occurring on the lobes of the caudal fin by stage 48 and on the remaining fins by stage 50. Taste bud primordia on the trunk proper do not begin to appear until stage 53, when the larvae begin to feed, and these receptors begin to erupt only in 1-week-old larvae. Fibers of the facial nerve, which innervate all external taste buds, ramify within the ectoderm prior to the first appearance of taste bud primordia or their precursors.

Animals↗

Mapping study of the parabrachial taste-responsive area for the anterior tongue in the golden hamster.

The locations of taste-responsive areas within the brainstem parabrachial nucleus (PBN), an obligatory taste relay in the golden hamster (Mesocricetus auratus), were mapped in relation to cytoarchitectural boundaries. The PBN was systematically searched for multiunit neural activity in response to a taste mixture composed of 0.1 M sucrose, 0.03 M NaCl, and 0.1 M KCl applied to the anterior tongue. Taste responses were located exclusively in one of three subdivisions of the medial PBN, which is thought to be specialized for gustatory processing, and in one of six subdivisions of the lateral PBN, which is thought to be specialized for general visceral processing. Based on Nissl-stained material, both the medial and lateral PBN subdivisions in the hamster were similar to those reported for the rat PBN. The largest group of taste-responsive cells encompassed two-thirds of the central medial subdivision, while a smaller group of taste cells was exclusively located within the ventral lateral subdivision. The two taste-responsive subdivisions are separated by the superior cerebellar peduncle and contain diverse cell types. The finding that anterior tongue taste may be exclusively represented in circumscribed cytoarchitecturally defined parts of two PBN divisions suggests that taste information from the anterior tongue is required for both specific gustatory and general visceral functions.

Animals↗

NCAM expression by subsets of taste cells is dependent upon innervation.

The expression of the neural cell adhesion molecule (NCAM) and distinct carbohydrate groups by cells of the taste buds of the rat vallate papilla was investigated by immunohistochemical and biochemical techniques. We employed antibodies against 1) the extracellular (mAb 3F4) and cytoplasmic (mAb 5B8) portions of the NCAM polypeptide, 2) the highly sialylated form of NCAM (mAb 5A5), 3) carbohydrate epitopes associated with glycosylated NCAM forms in the rat (mAb 2B8) or frog (mAb 9-OE) olfactory system, and also 4) the Lewisb blood group carbohydrate epitope (mAb CO431). NCAM mRNA was demonstrated by polymerase chain reaction (PCR) in samples of the vallate papilla, suggesting the presence of NCAM in cells of the taste buds. Antibodies against NCAM (mAbs 3F4 and 5B8) recognized a subset (about 20%) of cells within the vallate taste buds; fibers of the glossopharyngeal nerve, including those innervating the gustatory epithelium, were NCAM immunoreactive. Taste bud cells did not express polysialic acid (mAb 5A5), but mAb 5A5 immunoreactivity was observed on fibers of the IXth nerve, including a few that entered the taste buds. All or nearly all of the cells within the vallate taste buds were immunoreactive to mAb 2B8, whereas mAbs 9-OE and CO431 reacted with subsets of cells. The carbohydrates recognized by mAbs 2B8 and 9-OE were also abundantly expressed in the ducts and acini of the lingual salivary glands. Bilateral crush of the IXth nerve resulted in the loss of expression of all of these molecules from the gustatory epithelium. If cells of the taste bud express NCAM during their final stage(s) of differentiation, then NCAM could play a role(s) in the growth of gustatory axons toward their target epithelial cells and in the recognition between the nerve fibers and mature taste receptor cells, or among the taste bud cells themselves.

Animals↗

Liposome-mediated transfection of mature taste cells.

The introduction and expression of exogenous DNA in neurons is valuable for analyzing a range of cellular and molecular processes in the periphery, e.g., the roles of transduction-related proteins, the impact of growth factors on development and differentiation, and the function of promoters specific to cell type. However, sensory receptor cells, particularly chemosensory cells, have been difficult to transfect. We have successfully introduced plasmids expressing green and Discosoma Red fluorescent proteins (GFP and DsRed) into rat taste buds in primary culture. Transfection efficiency increased when delaminated taste epithelium was redigested with fresh protease, suggesting that a protective barrier of extracellular matrix surrounding taste cells may normally be present. Because taste buds are heterogeneous aggregates of cells, we used alpha-gustducin, neuronal cell adhesion molecule (NCAM), and neuronal ubiquitin carboxyl terminal hydrolase (PGP9.5), markers for defined subsets of mature taste cells, to demonstrate that liposome-mediated transfection targets multiple taste cell types. After testing eight commercially available lipids, we identified one, Transfast, that is most effective on taste cells. We also demonstrate the effectiveness of two common "promiscuous" promoters and one promoter that taste cells use endogenously. These studies should permit ex vivo strategies for studying development and cellular function in taste cells.

Animals↗

Responsiveness of solitario-parabrachial relay neurons to taste and mechanical stimulation applied to the oral cavity in rats.

A total of 311 units, responsive to natural stimulation of the oral cavity, were isolated from the rostral part of the solitary tract nucleus (NTS) of rats. Of these, 169 "taste neurons", activated by taste stimulation, and 142 mechanoreceptive units, exclusively sensitive to mechanical stimulation of the oral cavity, were found. Most taste units (62.3%) were also excited by mechanical stimulation. Forty-three (34.1%) of the 126 taste units examined were identified as solitario -parabrachial relay (SP) neurons by antidromic stimulation from the ipsilateral dorsal pons, while only eleven (12.6%) of the 87 mechano-receptive units were SP neurons. Taste SP neurons could be divided into two subgroups according to their antidromic latency; the fast SP units with an antidromic latency shorter than 9 ms and slow SP units with a longer antidromic latency. These two subgroups were not differentiated in any physiological properties except that the fast SP neurons were frequently excited by sucrose. Taste neurons were classified according to the best stimulus of the four basic taste solutions to produce the largest number of discharges in each neuron. All types of taste neurons were found among the SP and non-SP neurons, but only a small number of quinine-best neurons (n = 2) were found in the SP neuron group compared to the number of quinine-best neurons in the non-SP neuron group (n = 10). A histological examination of the recording sites revealed that taste relay neurons were found at the central or dorsal part of the nucleus but mechanoreceptive relay neurons were found at the peripheral part, although relay and non-relay neurons of either class were intermingled in the nucleus.

Animals↗

Influence of temperature on taste perception.

Daily experience tells us that temperature has a strong influence on how we taste. Despite the longstanding interest of many specialists in this aspect of taste, we are only starting to understand the molecular mechanisms underlying the temperature dependence of different taste modalities. Recent research has led to the identification of some strong thermosensitive molecules in the taste transduction pathway. The cold activation of the epithelial Na(+) channel and the heat activation of the taste variant of the vanilloid receptor (TRPV1t) may underlie the temperature dependence of salt responses. Heat activation of the transient receptor potential channel TRPM5 explains the enhancement of sweet taste perception by warm temperatures. Current development of methods to study taste cell physiology will help to determine the contribution of other temperature-sensitive events in the taste transduction pathways. Vice versa, the analysis of the thermodynamic properties of these events may assist to unveil the nature of several taste processes.

Animals↗

Perceived taste disturbance in adults: prevalence and association with oral and psychological factors and medication.

Taste disturbance may cause subjective discomfort and impair appetite and food intake. The aim of this study was to estimate the prevalence of perceived taste disturbance and analyze its association to age, gender, whole salivary flow rate, subjective oral dryness, burning mouth, medication, and psychological factors. Five hundred forty-seven men and 656 women aged 20 to 69 years were randomly selected from the Public Dental Health Service register in northern Sweden. Oral complaints were registered and whole salivary flow rate measured. Medication, anxiety, depression, and stress were assessed. Thirty individuals (2.5%), five men (0.9%) and 25 women (3.8%), reported perceived taste disturbances (distorted taste or loss of taste). In men, no individual with taste disturbance was found in the youngest and oldest age groups. The prevalence in the 30-39-year age group was 1.9% and in the 40-49-year group 1.8%. In women, one individual (1%) with taste disturbance was found in the youngest age group. In the 30-39-year group, the prevalence was 3.8%, increasing to 5.1% in the oldest age group. Illness, subjective oral dryness, state anxiety, perceived stress, depression, use of antiasthmatics, and trait anxiety were associated with taste disturbance. It was concluded that perceived taste disturbance might be an interaction of various health factors such as illness and mental condition.

Adult↗