Critical illness and changes in sensory perception

Assessment of Bitterness in Non-Charged Pharmaceuticals with a Taste Sensor: A Study on Substances with Xanthine Scaffold and Allopurinol

Taste sensors with an allostery approach have been studied to detect non-charged bitter substances, such as xanthine derivatives, used in foods (e.g., caffeine) or pharmaceuticals (e.g., etofylline). In this study, the authors modified a taste sensor with 3-bromo-2,6-dihydroxybenzoic acid and used it in conjunction with sensory tests to assess the bitterness of non-charged pharmaceuticals with xanthine scaffolds (i.e., acefylline and doxofylline), as well as allopurinol, an analogue of hypoxanthine. The results show that the sensor was able to differentiate between different levels of sample bitterness. For instance, when assessing a 30 mM sample solution, the sensor response to acefylline was 34.24 mV, which corresponded to the highest level of bitterness (τ = 3.50), while the response to allopurinol was lowest at 2.72 mV, corresponding to relatively weaker bitterness (τ = 0.50). Additionally, this study extended the application of the sensor to detect pentoxifylline, an active pharmaceutical ingredient in pediatric medicines. These results underscore the taste sensor's value as an additional tool for early-stage assessment and prediction of bitterness in non-charged pharmaceuticals.

Surviving critical COVID-19: How functionality, physical, mental and cognitive outcomes evolve?

PURPOSE

To analyze the long-term consequences of critical COVID-19, regarding physical, mental, cognitive and functional impairments, and to describe its evolution through time.

METHODS

Prospective cohort study, with consecutive inclusion of patients admitted due to SARS-CoV-2 to intensive care units(ICU) of a tertiary-care center, between May/2020 and September/2021. All included patients were included in Physical and Rehabilitation Medicine(PRM) inpatient programs during ICU stay. Eligible patients were evaluated on PRM appointments 6 and 12 months after ICU discharge. In each visit, physical examination and a predefined set of scales were applied, aiming to comprehensively evaluate the three domains (physical, mental and cognitive) of post-intensive care syndrome and the patients' functionality. Statistical analysis encompassed descriptive and univariate analysis.

RESULTS

A total of 42 patients were included: 66.7% males, mean age of 62 yo. In the physical domain, 6 months after ICU discharge, there was a significant reduction in quality of life (p-value = 0.034), muscle strength (p-value = 0.002), gait ability (p-value<0.001) and balance (p-values<0.001) and increased fatigue levels (p-value = 0.009), in comparison with reference values. Yet, a significative positive evolution was observed in all referred subdomains (p-values<0.05). Nevertheless, 12 months after discharge, muscle strength (p-value = 0.001), gait (p-value<0.001) and balance (p-value<0.001) were still significantly compromised. Regarding the mental domain, both at 6 and 12 months after discharge, the levels of anxiety and depression were significantly increased (p-values<0.001). Nonetheless, a positive evolution was also found (p-values<0.02). Cognitive performance was significantly impaired in comparison with reference values, both at 6 and 12 months (p-value<0.001). Yet, a global improvement was also depicted (p-value = 0.003). Six months after ICU discharge, 54.8% were autonomous in activities of daily living, a value that improved to 74.0% in the subsequent 6 months (p-value = 0.002).

CONCLUSION

Critical COVID-19 survivors present significant physical, mental and cognitive impairments 6 and 12 months after ICU discharge, despite their positive evolution through time.

Impact of taste/smell disturbances on dietary intakes and cachexia-related quality of life in patients with advanced cancer

PURPOSE

Taste and smell are used to enjoy meals; however, impairments of these sensory perceptions seriously impact health and eating habits. This study is aimed at investigating the impact of taste and smell disturbances on dietary intakes and cachexia-related quality of life (QOL) in patients with advanced cancer.

METHODS

Using a self-report questionnaire, we surveyed patients with advanced cancer undergoing treatment at 11 palliative care centers. Multivariate analyses were conducted to explore the impact of taste and smell disturbances on dietary intakes and cachexia-related QOL. Dietary intakes were assessed using the Ingesta-Verbal/Visual Analog Scale, while taste and smell disturbances were assessed using an 11-point Numeric Rating Scale (NRS). Cachexia-related QOL was assessed using the Functional Assessment of Anorexia/Cachexia Therapy Anorexia Cachexia Subscale (FAACT ACS).

RESULTS

Overall, 378 patients provided consent to participate. After excluding patients with missing data, data were analyzed for 343 patients. Among them, 35.6% (n = 122; 95% [confidence interval (CI)] 0.28-0.38) and 20.9% (n = 72; 95% CI 0.17-0.25) experienced disturbances in taste (NRS ≥ 1) and smell (NRS ≥ 1), respectively. Multivariate analyses revealed that, independent of performance status and cancer cachexia, taste and smell disturbances were significantly associated with worse dietary intakes and deteriorating FAACT ACS scores.

CONCLUSION

More severe taste and smell disturbances were associated with poorer dietary intakes and cachexia-related QOL. Diagnosing and treating such disturbances may improve dietary intakes and cachexia-related QOL, regardless of performance status and cachexia.

Sensory Capacities and Eating Behavior: Intriguing Results from a Large Cohort of Italian Individuals

Eating behavior (EB) is a complex system influenced by many factors, but an undisputed role is played by the senses. In this work, we examined the effect of the sensory capacities on EB in 1152 Italian adult individuals. After administering a questionnaire on EB and assessing sensory performance through standard audiometric, olfactory, and taste tests, the prevalence of reduced sensory capacities (RSCs) and the correlation with selected risk factors were calculated. Regression models, structural equation modelling, and conditional recursive partitioning were used to investigate the relationship between variables. Around 70% of the subjects show reduced capacities in at least one sense, with taste being the most prevalent (55.21%). Male sex, aging, and low educational level are risk factors for RSCs. The increased number of senses with reduced capacities is a predictor of diminished food adventurousness and lower liking for vegetables, fish, and alcoholic beverages, while reduced capacities (RCs) in taste is a predictor of lower liking for alcoholic beverages and sweets. Overall, in addition to providing an overall picture of RSCs in Italian samples, our study reveals the association of RSCs with EB variables. This finding could have a relevant role in influencing individuals’ dietary habits and, therefore, health status.

A Missing Voice: The Lingual Complex and Osteopathic Manual Medicine in the Context of Five Osteopathic Models

The five osteopathic models recognized by the American Association of Colleges of Osteopathic Medicine guide clinicians in the evaluation and therapeutic choice which must be the most appropriate concerning the patient's needs. Skeletal muscles represent an important interpretation, such as screening and treatment, on which these models are based. A muscle district that is not considered by the usual osteopathic practice is the tongue. The lingual complex has numerous functions, both local and systemic; it can adapt negatively in the presence of pathology, just as it can influence the body system in a non-physiological manner if it is a source of dysfunctions. This paper, the first of its kind in the panorama of scientific literature, briefly reviews the anatomy and neurophysiology of the tongue, trying to highlight the logic and the need to insert this muscle in the context of the five osteopathic models. The clinician's goal is to restore the patient's homeostasis, and we believe that this task is more concrete if the patient is approached after understanding all the contractile districts, including the tongue.

The association between olfactory dysfunction and cardiovascular disease and its risk factors in middle-aged and older adults

While previous studies have reported olfactory dysfunction (OD) in relation to cardiovascular disease (CVD), few population-based studies have investigated whether such associations differ by sex. The purpose of this study was to identify the association between CVD and its risk factors with OD, and the sex-associated differences within the general population. We examined 20,016 adults aged 40 and older from the Korean National Health and Nutrition Examination Survey. All subjects reported on their history of OD. CVD and its risk factors included coronary artery disease (CAD), stroke, hypertension, diabetes, obesity, abdominal obesity, and hypertriglyceridemia; logistic regression was used to analyse their associations with OD, and additive interaction was used to analyse the interaction between risk factors and sex. In males, CAD was more likely to be associated with OD (odds ratio [OR] 1.81, 95% confidence interval [CI] 1.05–3.14), whereas abdominal obesity was associated with OD in females (OR 1.39, 95% CI 1.06–1.84).Additive interaction were observed between abdominal obesity and female sex with a relative excess risk of interaction of 0.45 (95% CI 0.26–0.63). Our findings suggest the relationship between OD and CVD and its risk factors and sex-associated differences among middle-aged and older adults.

Prospective assessment of gustatory function after radiotherapy for head and neck cancers

BACKGROUND

Taste disorders are major causes of morbidity in patients undergoing head and neck irradiation. We quantitatively assessed the gustatory function of patients with head and neck cancers who underwent radiotherapy using recently developed standardised tools for measuring taste.

METHODS

Twenty patients undergoing head and neck irradiation responded to a specific questionnaire and were assessed by olfactory and gustatory function tests. To assess changes over time, testing was performed before, immediately after, and at 2- and 4-week intervals following the start of radiotherapy. Concurrently, patients were evaluated for xerostomia from radiotherapy.

RESULTS

A decrease in the taste recognition threshold was observed in the second week after the beginning of radiotherapy. The taste detection threshold improved within the 14th-18th week. Most affected patients demonstrated that their gustatory function primarily decreased independent of the olfactory function. Disturbances in taste were exponentially worsened beyond an accumulated dose of 30 Gy and involved all tastants. According to a multivariate analysis, radiation-induced taste impairment was not influenced by the degree of xerostomia. However, there was an association between the dose of irradiation and the severity of taste disturbance.

CONCLUSIONS

In this preliminary study, we found that the taste function was worse 2 weeks after the start of radiotherapy and returned to pretreatment levels within 4.5 months. Taste disturbances were exponentially worse beyond an accumulated dose of 20 Gy. Taste dysfunction after radiotherapy was not influenced by the degree of xerostomia, whereas only the dose of irradiation was associated with the severity of taste dysfunction.

Sensory Profile of Adults with Reduced Food Intake and the Potential Roles of Nutrition and Physical Activity Interventions

The sensory profile, referring to sight, smell, taste, hearing, and touch, plays an essential role in optimizing the habitual intake of energy and macronutrients. However, specific populations, such as older adults, are known to have impaired energy intake. In this paper, the relevance of sensory impairments in this older population is described, and the extent to which nutritional and physical activity interventions can modulate these sensory responses when food intake is insufficient is explored. With aging, all senses deteriorate, and in most cases, such deteriorations diminish the nutritional response. The only exception is sight, for which both positive and negative impacts on nutritional response have been reported. From a prevention perspective, nutritional interventions have been understudied, and to date, only hearing is known to be positively affected by a good nutritional profile. In comparison, physical activity has been more frequently studied in this context, and is linked to an improved preservation of 4 senses. Regarding treatment, very few studies have directly targeted sensory training, and the focus of research has tended to be on nutrition and physical activity intervention. Sensory training, and nutritional and physical activity treatments all have beneficial effects on the senses. In the future, researchers should focus on exploring gaps in the literature specifically concerning prevention, treatment, and sensory response to understand how to improve the efficacy of current approaches. In order to maintain sensory acuity and recover from sensory impairment, the current state of knowledge supports the importance of improving nutritional habits as well as physical activity early on in life. A combined approach, linking a detailed lifestyle profile with the assessment of numerous senses and one or more interventional approaches (nutrition, physical activity, sensory training, etc.), would be required to identify effective strategies to improve the nutritional state of older individuals.

Persimmon fruit enhanced quality characteristics and antioxidant potential of beer

Various adjuncts, including fruits, are added for flavoring beer, one of the most famous beverages in the world. The influence of persimmon fruit on antioxidant activities and quality characteristics of beer was investigated in this study. The antioxidant activities measured through DPPH and superoxide and hydroxyl anions scavenging potentials as well as total polyphenol contents of the persimmon-treated beer were significantly (p < 0.05) high compared to the control. The mineral elements Mg, K, and Ca were also significantly (p < 0.05) increased, however toxic heavy metals were not detected in the persimmon beer. Among the persimmon beer samples, the overall acceptance value was significantly (p < 0.05) high when the beer was prepared by adding 150 g of the fruit in 10 L of water. The results suggested that an addition of 150 g of persimmon fruit per 10 L of water could better enrich the nutritional, organoleptic, and antioxidant potentials of beer.

Influence of medications on taste and smell

Medications frequently have chemosensory side effects that can adversely affect compliance with medical treatment regimens. Hundreds of drugs have been reported to induce unpleasant tastes and/or odors as well as altered chemosensations when administered alone or in combination with other medications. Some chemosensory complaints are due to the sensory properties of the drug itself such as aversive bitter and metallic tastes. However, most chemosensory side effects of drugs are due to alterations in the transduction pathways, biochemical targets, enzymes, and transporters by the offending medications. Studies of chemosensory perception in medicated older individuals have found that taste and smell loss is greatest for those consuming the largest number of prescription drugs. There are no standard treatments for drug-induced chemosensory disorders because each drug has unique biological effects. However, there are a few treatment options to ameliorate chemosensory alterations including addition of simulated flavors to food to compensate for losses and to override offending tastes and smells.

Determinants of Single and Multiple Sensory Impairments in an Urban Population

OBJECTIVE

To describe the co-occurrence pattern and determinants of auditory, olfactory, visual, and gustatory impairment across the life spectrum of adults.

STUDY DESIGN

Cross-sectional analysis.

SETTING

An urban population.

SUBJECTS AND METHOD

In total, 1208 persons from the general adult population (age range, 25-74 years; 46.7% men) were included. Sensory impairments were assessed with validated tests. Alternating logistic regression was applied to characterize (1) the dependence of sensory impairments on selected independent variables and (2) the pairwise association between sensory impairments. The dependence of impairment grade (no to multisensory impairment) on the same set of independent variables was examined using ordinal logistic regression.

RESULTS

The prevalence of single sensory impairment was 38.8%, of dual 27.3%, and of multisensory impairment 7.5%. Auditory impairment was the most frequent impairment type (43.9%), followed by olfactory (21.5%), gustatory (20.3%), and visual impairment (14.1%). Besides age and sex, social status (odds ratio [OR], 2.61; 95% confidence interval [CI], 1.80-3.79), smoking status (OR, 1.45; 95% CI, 1.12-1.88), and diabetes (OR, 1.75; 95% CI, 1.16-2.63) were related to an elevated odds of moving from a lower into a higher impairment category.

CONCLUSIONS

The presence of certain risk factors, such as a low social status, diabetes, and smoking, appears likely to increase the risk of multisensory impairment.

‘Acceptability’ of a new oral suspension formulation of mercaptopurine in children with acute lymphoblastic leukaemia

Aim

The aim of this questionnaire-based survey was to determine the ‘acceptability’ of Xaluprine®, a new oral liquid formulation of mercaptopurine, when administered chronically to children during the maintenance treatment phase of acute lymphoblastic leukaemia.

Patients and methods

This was a single centre survey of children (aged 3 to 16 years) and their parents at a routine follow-up visit during the maintenance phase of acute lymphoblastic leukaemica treatment. The questionnaire probed for their views on overall acceptability such as taste, smell, incidences of vomiting, ease and willingness to take Xaluprine® on a daily basis, and utilised a 5-point facial hedonic scale (1 = bad, 5 = good) as well as open/closed questions.

Results

Twenty-two children were recruited; 17 (77%) scored taste between 3 and 5 (‘okay’ to ‘good’) and 20 (91%) scored smell between 3 and 5. Only four children (18%) reported an aftertaste. Of the five children (23%) who scored taste as 1 or 2 (‘bad’), three found taking all oral medicines difficult. Six children (27%) reported vomiting, but this was not considered related to Xaluprine®. Seven children (32%) sometimes complained that they did not want to take Xaluprine®; 15 (68%) never complained. In response to the question, ‘How easy is it for you to take Xaluprine®?’ 18 children (82%) reported that it was ‘Easy all the time.’ This was more favourable than other oral liquid medicines that they were taking concurrently.

Conclusion

The results of this survey show that Xaluprine® has good overall acceptability in the paediatric population and suggests that Xaluprine® is an important, alternative, age-appropriate formulation of mercaptopurine.

Nutrition rehabilitation in the intensive care unit

The maintenance of homeostasis after severe injury requires the restoration of the physiological regulation of food intake. A wide array of functional alterations can hinder the intake of adequate amounts of nutrients to support the recovery from critical illness. These alterations encompass changes in the preprandial phase, reflected by a loss of appetite; changes in the prandial phase, yielding swallowing disorders; and changes in the postprandial phase, including impairments of gastric emptying, gut motility, and satiety. This tutorial aims to review these often overlooked features and to suggest recommendations for the nutrition rehabilitation of the critically ill.

A prospective cohort study of the effects of adjuvant breast cancer chemotherapy on taste function, food liking, appetite and associated nutritional outcomes

BACKGROUND

'Taste' changes are commonly reported during chemotherapy. It is unclear to what extent this relates to actual changes in taste function or to changes in appetite and food liking and how these changes affect dietary intake and nutritional status.

PATIENTS AND METHODS

This prospective, repeated measures cohort study recruited participants from three oncology clinics. Women (n = 52) prescribed adjuvant chemotherapy underwent standardised testing of taste perception, appetite and food liking at six time points to measure change from baseline. Associations between taste and hedonic changes and nutritional outcomes were examined.

RESULTS

Taste function was significantly reduced early in chemotherapy cycles (p<0.05) but showed recovery by late in the cycle. Ability to correctly identify salty, sour and umami tastants was reduced. Liking of sweet food decreased early and mid-cycle (p<0.01) but not late cycle. Liking of savory food was not significantly affected. Appetite decreased early in the cycle (p<0.001). Reduced taste function was associated with lowest kilojoule intake (r = 0.31; p = 0.008) as was appetite loss with reduced kilojoule (r = 0.34; p = 0.002) and protein intake (r = 0.36; p = 0.001) early in the third chemotherapy cycle. Decreased appetite early in the third and final chemotherapy cycles was associated with a decline in BMI (p = <0.0005) over the study period. Resolution of taste function, food liking and appetite was observed 8 weeks after chemotherapy completion. There was no association between taste change and dry mouth, oral mucositis or nausea.

CONCLUSION

The results reveal, for the first time, the cyclical yet transient effects of adjuvant chemotherapy on taste function and the link between taste and hedonic changes, dietary intake and nutritional outcomes. The results should be used to inform reliable pre-chemotherapy education.

The endocannabinoid system and appetite: relevance for food reward

Mounting evidence substantiates the central role of the endocannabinoid system (ECS) in the modulation of both homeostatic and hedonic elements of appetite and food intake. Conversely, feeding status and dietary patterns directly influence activity of the ECS. Following a general introduction on the functioning of the ECS, the present review specifically addresses its role in the modulation of hedonic eating. Humans possess strong motivational systems triggered by rewarding aspects of food. Food reward is comprised of two components: one appetitive (orienting towards food); the other consummatory (hedonic evaluation), also referred to as 'wanting' and 'liking', respectively. Endocannabinoid tone seems to influence both the motivation to feed and the hedonic value of foods, probably by modifying palatability. Human physiology underlying hedonic eating is still not fully understood. A better understanding of the role of the ECS in the rewarding value of specific foods or diets could offer new possibilities to optimise the balance between energy and nutrient intake for different target groups. These groups include the obese and overweight, and potentially individuals suffering from malnutrition. Examples for the latter group are patients with disease-related anorexia, as well as the growing population of frail elderly suffering from persistent loss of food enjoyment and appetite resulting in malnutrition and involuntary weight loss. It has become clear that the psychobiology of food hedonics is extremely complex and the clinical failure of CB1 inverse agonists including rimonabant (Accomplia®) has shown that 'quick wins' in this field are unlikely.

Impaired taste and increased mortality in acutely hospitalized older people

Taste ability is known to be impaired in elderly and even more so in acutely hospitalized elderly people. To our knowledge, no study has investigated the association between taste impairment and mortality. Our aim was to examine this association in acutely hospitalized older people. In a prospective study, 200 acutely hospitalized elderly people ≥70 years of age were included between November 2009 and October 2010 at the Oslo University Hospital, Norway. Exclusion criteria were cognitive impairment, nursing home residency, and terminal diseases. Comorbidity was registered with the Cumulative Illness Rating Scale, in addition to recording of age, gender, smoking, education, and number of medications. Taste ability was assessed quantitatively with the "taste strips method" in 174 patients (mean age: 84 years). Mortality until 1 January 2012 was obtained from hospital records. Fifty-six patients died during the observation period. The relative risk of death in total taste score quartile 4 compared with total taste score quartile 1 was 0.31 (95% confidence interval [95% CI]: 0.14-0.69, P = 0.004), after adjusting for age, gender, smoking, education, and Cumulative Illness Rating Scale. Adjusted 1-year mortality decreased from 30% in total taste score quartile 1 to 9% in total taste score quartile 4. Thus, impaired taste appears to be strongly associated with mortality in acutely hospitalized elderly people.

Aroma and taste perceptions with Alzheimer disease and stroke

Chemosensory disorders of smell or taste in humans have been attributed to various physiological and environmental factors including aging and disease conditions. Aroma and taste greatly condition our food preference, selection and, consumption; the decreased appetite in patients with known neurodegenerative diseases may lead to dietary restrictions that could negatively impact nutritional and health status. The decline in olfactory and gustatory systems in patients with Alzheimer disease and various types of stroke are described.

Zinc deficiency and taste perception in the elderly

Taste, one of the major senses in humans, is the ability to detect the flavor of substances such as food, certain minerals, and poisons. Taste distortions in human beings have been attributed to various physiological and environmental factors including aging and disease conditions. Given the fact that taste is one of the most important factors in food preference, selection, and consumption, the decreased appetite in the elderly, probably due to disease conditions, may lead to dietary restrictions that could negatively impact nutritional and health status. The role of zinc on taste distortion in the elderly population and taste impairment are described. Although several studies demonstrate the associative nature of taste degeneration with age, additional investigations are required to clarify the mechanisms by which taste perception is altered with age.

Taste loss in hospitalized multimorbid elderly subjects

BACKGROUND

Loss of the sense of taste is common among older people. Morbidities and polypharmacy may contribute to the age-related decline in gustatory function. The aims of the present study were to investigate taste perception in elderly hospitalized patients by comparing their taste recognition thresholds with those of healthy, free-living elderly individuals and to identify potential determinants of taste loss.

METHODS

The participants in this observational study were 55 elderly patients hospitalized in the acute geriatric section of the Department of Medical and Surgical Sciences at Padova University and 41 free-living individuals aged older than 65 years, randomly recruited from elderly people attending mild fitness programs at public gymnasiums in Padova. Data were collected on nutrition, health, cognitive, and functional status for all participants. Gustatory capabilities were assessed using aqueous solutions of sucrose, sodium chloride, citric acid, and quinine hydrochloride (representing sweet, salty, sour, and bitter stimuli, respectively), and taste recognition thresholds were measured in both groups.

RESULTS

In comparison with the free-living elderly subjects, those in hospital were significantly less able to recognize the taste of citric acid (P < 0.05). Low citric acid sensitivity was independently associated with advanced age (≥75 years; odds ratio [OR] 3.01, 95% confidence interval [CI] 1.01-9.82), polypharmacy (number of prescribed drugs ≥ 4; OR 2.74, 95% CI 1.01-7.72), and poor nutritional status (as assessed by Mini Nutritional Assessment score < 23.5; OR 5.08, 95% CI 1.76-14.6).

CONCLUSION

Because gustatory impairment may reduce a person's appetite and lead to inadequate dietary intake, compensatory nutritional measures, such as the use of flavor-enhanced foods, should be strongly encouraged, particularly in the hospital setting.

Greater amount of visual information exacerbates force control in older adults during constant isometric contractions

The purpose of this study was to compare control of force and modulation of agonist muscle activity of young and older adults when the amount of visual feedback was varied at two different force levels. Ten young adults (25 years ± 4 years, 5 men and 5 women) and ten older adults (71 years ± 5 years, 4 men and 6 women) were instructed to accurately match a constant target force at 2 and 30% of their maximal isometric force with abduction of the index finger. Each trial lasted 35 s, and the amount of visual feedback was varied by changing the visual angle at 0.05, 0.5, and 1.5°. Each subject performed three trials for each visual angle condition. Force variability was quantified as the standard deviation and coefficient of variation (CV) of force. Modulation of the agonist muscle activity was quantified as the normalized power spectrum density of the EMG signal recorded from two pairs of bipolar electrodes placed on the first dorsal interosseus muscle. The frequency bands of interest were between 5 and 100 Hz. There were significant age-associated differences in force control with changes in the amount of visual feedback. The CV of force did not change with visual angle for young adults, whereas it increased for older adults. Although older adults exhibited similar CV of force to young adults at 0.05° (5.95 ± 0.67 vs. 5.47 ± 0.5), older adults exhibited greater CV of force than young adults at 0.5° (8.49 ± 1.34 vs. 5.05 ± 0.5) and 1.5° (8.23 ± 1.12 vs. 5.49 ± 0.6). In addition, there were age-associated differences in the modulation of the agonist muscle activity. Young adults increased normalized power in the EMG signal from 13 to 60 Hz with an increase in visual angle, whereas older adults did not. These findings suggest that greater amount of visual information may be detrimental to the control of a constant isometric contraction in older adults, and this impairment may be due to their inability to effectively modulate the motor neuron pool of the agonist muscle.

Hospital catering systems and their impact on the sensorial profile of foods provided to older patients in the UK

Impaired sensorial perception is very common in older people and low sensorial quality of foods is associated with decreased appetite and dietary intake. Hospital undernutrition in older patients could be linked to sensorial quality of hospital food if the quality were low or inappropriate for older people. The aim of this study was to examine changes in the sensorial quality of different foods that occur as a result of the food journey (i.e. freezing, regeneration, etc.) in the most common hospital catering systems in the UK. A trained sensory panel assessed sensorial descriptors of certain foods with and without the hospital food journey as it occurs in the in-house and cook/freeze systems. The results showed effects of the food journey on a small number of sensorial descriptors related to flavour, appearance and mouthfeel. The majority of these effects were due to temperature changes, which caused accumulation of condensation. A daily variation in sensorial descriptors was also detected and in some cases it was greater than the effect of the food journey. This study has shown that changes occur in the sensory quality of meals due to hospital food journeys, however these changes were small and are not expected to substantially contribute to acceptability or have a major role in hospital malnutrition.

Neuroinflammation resulting from covert brain invasion by common viruses - a potential role in local and global neurodegeneration

Neurodegenerative diseases are a horrendous burden for their victims, their families, and society as a whole. For half a century scientists have pursued the hypothesis that these diseases involve a chronic viral infection in the brain. However, efforts to consistently detect a specific virus in brains of patients with such diseases as Alzheimer's or multiple sclerosis have generally failed. Neuropathologists have become increasingly aware that most patients with neurodegenerative diseases demonstrate marked deterioration of the brain olfactory bulb in addition to brain targets that define the specific disease. In fact, the loss of the sense of smell may precede overt neurological symptoms by many years. This realization that the olfactory bulb is a common target in neurodegenerative diseases suggests the possibility that microbes and/or toxins in inhaled air may play a role in their pathogenesis. With regard to inhaled viruses, neuropathologists have focused on those viruses that infect and kill neurons. However, a recent study shows that a respiratory virus with no neurotropic properties can rapidly invade the mouse olfactory bulb from the nasal cavity. Available data suggest that this strain of influenza is passively transported to the bulb via the olfactory nerves (mechanism unknown), and is taken up by glial cells in the outer layers of the bulb. The infected glial cells appear to be activated by the virus, secrete proinflammatory cytokines, and block further spread of virus within the brain. At the time that influenza symptoms become apparent (15 h post-infection), but not prior to symptom onset (10 h post-infection), proinflammatory cytokine-expressing neurons are increased in olfactory cortical pathways and hypothalamus as well as in the olfactory bulb. The mice go on to die of pneumonitis with severe acute phase and respiratory disease symptoms but no classical neurological symptoms. While much remains to be learned about this intranasal influenza-brain invasion model, it suggests the hypothesis that common viruses encountered in our daily life may initiate neuroinflammation via olfactory neural networks. The numerous viruses that we inhale during a lifetime might cause the death of only a few neurons per infection, but this minor damage would accumulate over time and contribute to age-related brain shrinkage and/or neurodegenerative diseases. Elderly individuals with a strong innate inflammatory system, or ongoing systemic inflammation (or both), might be most susceptible to these outcomes. The evidence for the hypothesis that common respiratory viruses may contribute to neurodegenerative processes is developed in the accompanying article.

The elderly as a sensitive population in environmental exposures: making the case

The US population is aging. CDC has estimated that 20% of all Americans will be 65 or older by the year 2030. As a part of the aging process, the body gradually deteriorates and physiologic and metabolic limitations arise. Changes that occur in organ anatomy and function present challenges for dealing with environmental stressors of all kinds, ranging from temperature regulation to drug metabolism and excretion. The elderly are not just older adults, but rather are individuals with unique challenges and different medical needs than younger adults. The ability of the body to respond to physiological challenge presented by environmental chemicals is dependent upon the health of the organ systems that eliminate those substances from the body. Any compromise in the function of those organ systems may result in a decrease in the body's ability to protect itself from the adverse effects of xenobiotics. To investigate this issue, we performed an organ system-by-organ system review of the effects of human aging and the implications for such aging on susceptibility to drugs and xenobiotics. Birnbaum (1991) reported almost 20 years ago that it was clear that the pharmacokinetic behavior of environmental chemicals is, in many cases, altered during aging. Yet, to date, there is a paucity of data regarding recorded effects of environmental chemicals on elderly individuals. As a result, we have to rely on what is known about the effects of aging and the existing data regarding the metabolism, excretion, and adverse effects of prescription medications in that population to determine whether the elderly might be at greater risk when exposed to environmental substances. With increasing life expectancy, more and more people will confront the problems associated with advancing years. Moreover, although proper diet and exercise may lessen the immediate severity of some aspects of aging, the process will continue to gradually degrade the ability to cope with a variety of injuries and diseases. Thus, the adverse effects of long-term, low-level exposure to environmental substances will have a longer time to be manifested in a physiologically weakened elderly population. When such exposures are coupled with concurrent exposure to prescription medications, the effects could be devastating. Public health officials must be knowledgeable about the sensitivity of the growing elderly population, and ensure that the use of health guidance values (HGVs) for environmental contaminants and other substances give consideration to this physiologically compromised segment of the population.

Sour ageusia in two individuals implicates ion channels of the ASIC and PKD families in human sour taste perception at the anterior tongue

BACKGROUND

The perception of sour taste in humans is incompletely understood at the receptor cell level. We report here on two patients with an acquired sour ageusia. Each patient was unresponsive to sour stimuli, but both showed normal responses to bitter, sweet, and salty stimuli.

METHODS AND FINDINGS

Lingual fungiform papillae, containing taste cells, were obtained by biopsy from the two patients, and from three sour-normal individuals, and analyzed by RT-PCR. The following transcripts were undetectable in the patients, even after 50 cycles of amplification, but readily detectable in the sour-normal subjects: acid sensing ion channels (ASICs) 1a, 1beta, 2a, 2b, and 3; and polycystic kidney disease (PKD) channels PKD1L3 and PKD2L1. Patients and sour-normals expressed the taste-related phospholipase C-beta2, the delta-subunit of epithelial sodium channel (ENaC) and the bitter receptor T2R14, as well as beta-actin. Genomic analysis of one patient, using buccal tissue, did not show absence of the genes for ASIC1a and PKD2L1. Immunohistochemistry of fungiform papillae from sour-normal subjects revealed labeling of taste bud cells by antibodies to ASICs 1a and 1beta, PKD2L1, phospholipase C-beta2, and delta-ENaC. An antibody to PKD1L3 labeled tissue outside taste bud cells.

CONCLUSIONS

These data suggest a role for ASICs and PKDs in human sour perception. This is the first report of sour ageusia in humans, and the very existence of such individuals ("natural knockouts") suggests a cell lineage for sour that is independent of the other taste modalities.

Effects of aging on the human taste system

Losses in taste perception as well as distortions of gustatory function occur with greater frequency in older individuals, and these changes are exacerbated by certain medical conditions, pharmacologic interventions, radiation, and exposure to toxic chemicals. Medications, especially drug-drug interactions, are the most significant yet underappreciated contributors to taste disorders in the elderly. Taste disorders frequently occur when the fraction of an orally administered drug dose that reaches the systemic circulation is markedly increased due to inhibition (by a coadministered drug) of the efflux transporter P-glycoprotein and/or inhibition of the cytochrome P450 metabolism system, which normally limit systemic availability of drugs. The supratherapeutic plasma drug concentrations that result from drug-drug interactions can induce a taste from the blood side of taste cells (intravascular taste), alter taste cell biochemistry, and/or modify other aspects of the taste pathways.

Assessing alterations in taste and their impact on cancer care

PURPOSE OF REVIEW

As the discipline of supportive and palliative cancer care grows, there is increasing acknowledgement of taste and smell alterations (TSAs) as barriers to nutrient intake and detriments to the food-related quality of life and well being of the population. The focus of this brief review is to summarize the recent advances regarding the cause and nature of TSAs and patients' perceptions of TSAs and to identify promising approaches for the alleviation of TSAs.

RECENT FINDINGS

Individual variations in the nature of TSAs exist and chemosensory changes have been established as an important quality of life issue associated with prognosis. The development and partial recovery of radiation therapy induced TSAs have been observed in longitudinal studies. Flavor enhancement has been found to improve patient-reported taste and smell capabilities. Patient-reported tools and qualitative methodologies have provided insight into the impact of TSAs on food-related quality of life and have been used with clinical measures to relate patient's perception to objective outcomes.

SUMMARY

A variety of approaches to the assessment of TSAs continue to generate a description of the development, duration and recovery of distorted chemosensory perception in cancer patients. Attention to individual variation in the nature and severity of TSAs as well as nutritional support and focus on flavorful foods can enhance patients' well being and food-related quality of life.