Age and Sex-Related Differences in the Tongue Pressure Generated during Maximum Isometric and Swallowing Tasks by Healthy Chinese Adults

Age-related sex differences in tongue strength and muscle morphometry in a rat model

OBJECTIVE

To investigate potential effects of sex on voluntary tongue strength, evoked twitch and tetanic tension, speed of contraction, and muscle fiber cross-sectional area in the muscles of the rat tongue. Additionally, we aimed to determine whether estrous cycle stage impacts any of the dependent variables as a pilot investigation into the use of female rats in a model of tongue exercise and aging.

DESIGN

Fischer 344-Brown Norway male and female rats in two age groups (16 middle-aged, 16 young-adult) were trained to use a tongue force operandum. Tongue muscle contraction, myosin heavy chain (MyHC) composition, and cross section area of the genioglossus and styloglossus muscles were examined. Vaginal lavage determined estrous cycle stage of the female rats daily.

RESULTS

The female group had significantly lower evoked twitch and tetanic tension, longer contraction times, and a smaller proportion of MyHC type IIa and MyHC type IIx in the styloglossus muscle. There was no significant sex effect in maximal voluntary tongue force (MVTF) despite a significant weight difference between the male and female groups. There were no significant age or sex effects in the genioglossus. Estrous cycle stage did not have a significant effect on any of the dependent variables.

CONCLUSIONS

Sex and age both have a significant effect on tongue muscle structure and physiology. While the female group showed reduced contraction speed and maximal twitch and tetanic tension relative to the male group, differences in muscle morphology appeared to vary by muscle.

Evaluation of Esophageal Dysphagia in Elderly Patients

PURPOSE OF REVIEW

While guidelines exist for the evaluation and management of esophageal dysphagia in the general population, dysphagia disproportionately affects the elderly. In this article, we reviewed the literature on evaluating esophageal dysphagia in elderly patients and proposed a diagnostic algorithm based on this evidence.

RECENT FINDINGS

In older patients, dysphagia is often well compensated for by altered eating habits and physiologic changes, underreported by patients, and missed by healthcare providers. Once identified, dysphagia should be differentiated into oropharyngeal and esophageal dysphagia to guide diagnostic workup. For esophageal dysphagia, this review proposes starting with endoscopy with biopsies, given its relative safety even in older patients and potential for interventional therapy. If endoscopy shows a structural or mechanical cause, then further cross-sectional imaging should be considered to assess for extrinsic compression, and same session endoscopic dilation should be considered for strictures. If biopsies and endoscopy are normal, then esophageal dysmotility is more likely, and high-resolution manometry and additional workup should be performed following the updated Chicago Classification. Even after diagnosis of the root cause, complications including malnutrition and aspiration pneumonia should also be assessed and monitored, as they both result from and can further contribute to dysphagia. The successful evaluation of esophageal dysphagia in elderly patients requires a thorough, standardized approach to collecting a history, selection of appropriate diagnostic workup, and assessment of risk of potential complications, including malnutrition and aspiration.

Frictional behaviour of plant proteins in soft contacts: unveiling nanoscale mechanisms

Despite the significance of nanotribology in the design of functional biomaterials, little is known about nanoscale friction in the presence of protein-coated soft contact surfaces. Here, we report a detailed investigation of frictional behaviour of sustainable plant proteins at the nanoscale for the first time, using deformable bio-relevant surfaces that achieve biologically relevant contact pressures. A combination of atomic force microscopy, quartz crystal microbalance with dissipation monitoring, and friction force microscopy with soft polydimethylsiloxane (PDMS, 150 kPa) surfaces was employed to elucidate the frictional properties of model plant proteins, i.e. lupine, pea, and potato proteins at the nanoscale while systematically varying the pH and ionic strength. Interactions of these plant proteins with purified mucins were also probed. We provide the much-needed direct experimental evidence that the main factor dictating the frictional properties of plant proteins is their affinity towards the surface, followed by the degree of protein film hydration. Proteins with high surface affinity, such as pea and potato protein, have better lubricating performance than lupine at the nanoscale. Other minor factors that drive lubrication are surface interactions between sliding bodies, especially at low load, whilst jamming of the contact area caused by larger protein aggregates increases friction. Novel findings reveal that interactions between plant proteins and mucins lead to superior lubricating properties, by combining high surface affinity from the plant proteins and high hydration by mucins. We anticipate that fundamental understanding gained from this work will set the stage for the design of a plethora of sustainable biomaterials and food with optimum nanolubrication performance.

Population-based reference values for tongue pressure in Japanese older adults: A pooled analysis of over 5,000 participants

PURPOSE

To establish age- and sex-specific population reference values for tongue pressure (TP) in community-dwelling Japanese older adults.

METHODS

For this analysis, we pooled four population-based studies on community-dwelling adults aged ≥65 years that measured TP using a JMS tongue pressure measuring device. We calculated the means and deciles of TP per 5-year age group for each sex. We also estimated age trends in TP for men and women.

RESULTS

In total, 5,083 individuals (2,150 men and 2,933 women, with a mean [standard deviation] age of 75.2 [6.5] years) were included in the present analysis. In male participants, the mean (standard deviation) TPs for ages 65-69, 70-74, 75-79, 80-84, and ≥85 years were 34.0 (8.4), 32.2 (8.1), 30.8 (8.3), 28.4 (8.9), and 24.4 (8.2) kPa, respectively. In female participants, the corresponding values were 31.5 (7.1), 30.5 (7.5), 29.6 (7.3), 28.4 (8.0), and 26.4 (7.6) kPa, respectively. For both sexes, there were significant declining trends in TP with advanced age. In addition, the interaction between age and sex had a significant effect on TP (regression coefficient [95% confidence interval] = -0.18 [-0.25 to -0.11] when age was modeled as a continuous variable and sex was modeled as a categorical variable [coded as 0=women, 1=men]).

CONCLUSIONS

This study determined age- and sex-specific reference values for TP, presented as means and deciles, in community-dwelling Japanese older adults aged ≥65 years. This study also demonstrated sex differences in age-related declines in TP.

Bioenergetic Evaluation of Muscle Fatigue in Murine Tongue

Muscle fatigue is the diminution of force required for a particular action over time. Fatigue may be particularly pronounced in aging muscles, including those used for swallowing actions. Because risk for swallowing impairment (dysphagia) increases with aging, the contribution of muscle fatigue to age-related dysphagia is an emerging area of interest. The use of animal models, such as mice and rats (murine models) allows experimental paradigms for studying the relationship between muscle fatigue and swallowing function with a high degree of biological precision that is not possible in human studies. The goal of this article is to review basic experimental approaches to the study of murine tongue muscle fatigue related to dysphagia. Traditionally, murine muscle fatigue has been studied in limb muscles through direct muscle stimulation and behavioral exercise paradigms. As such, physiological and bioenergetic markers of muscle fatigue that have been validated in limb muscles may be applicable in studies of cranial muscle fatigue with appropriate modifications to account for differences in muscle architecture, innervation ratio, and skeletal support. Murine exercise paradigms may be used to elicit acute fatigue in tongue muscles, thereby enabling study of putative muscular adaptations. Using these approaches, hypotheses can be developed and tested in mice and rats to allow for future focused studies in human subjects geared toward developing and optimizing treatments for age-related dysphagia.