Ayako Nakane

Inter‐ and intra‐rater reliability in fibroptic endoscopic evaluation of swallowing

Fibroptic endoscopic evaluation of swallowing (FEES) is a useful way for dentists to evaluate oropharyngeal dysfunction. However, no study has paid attention to inter- and intra-rater reliability of FEES evaluation about oropharyngeal dysfunction. The purpose of this study is to verify whether dentist who trained and experienced for evaluation of dysphagia could diagnose oropharyngeal function with FEES. Nine dentists independently evaluated FEES images of 10 cases four times each. At first, evaluators performed the first evaluation without consulting the evaluative criteria. Subsequently, evaluators independently re-evaluated at 1-week intervals for three consecutive weeks, consulting the evaluative criteria. And then, inter- and intra-rater reliability was calculated. Cohens Kappa was used to assess reliability. The results found that overall inter-rater reliability was 0·35±0·04 (first evaluation), 0·45±0·05 (s), 0·44±0·05 (third) and 0·46±0·04 (fourth). Most of inter-rater reliability related to aspiration was moderate to high, but lower for categories that evaluated timing of swallowing and mastication. In contrast, intra-rater reliability was moderate to high for overall categories, at 0·53±0·04 (first vs. second evaluation), 0·55±0·04 (first vs. third), 0·53±0·04 (first vs. fourth), 0·55±0·03 (second vs. third), 0·60±0·03 (second vs. fourth) and 0·78±0·03 (third vs. fourth). FEES is reliable for experienced dentists to diagnose oropharyngeal function. Moreover, repeated evaluation with the aids of evaluative criteria is useful to improve the reliability of FEES.

Comparative morphology of the osteocyte lacunocanalicular system in various vertebrates

Osteocytes are embedded in the bone matrix, and they communicate with adjacent osteocytes, osteoblasts, and osteoclasts through the osteocyte lacunocanalicular system. Osteocytes are believed to be essential for the maintenance of bone homeostasis because they regulate mechanical sensing and mineral metabolism in mammalian bones; however, osteocyte morphology in other vertebrates has not been well documented. We conducted a comparative study on the morphology of osteocytes and the lacunocanalicular system of the following vertebrates: two teleost fishes [medaka (Oryzias latipes), and zebrafish (Danio rerio)], three amphibians [African clawed frog (Xenopus laevis), black-spotted pond frog (Rana nigromaculata), and Japanese fire-bellied newt (Cynops pyrrhogaster)], two reptiles [four-toed tortoise (Testudo horsfieldii) and green iguana (Iguana iguana)], and two mammals (laboratory mouse C57BL6 and human). The distribution of the osteocyte lacunocanalicular system in all these animals was investigated using the modified silver staining and the fluorescein-conjugated phalloidin staining methods. Bones of medaka had few osteocytes (acellular bone). Bones of zebrafish contained osteocytes (cellular bone) but had a poorly developed osteocyte lacunocanalicular system. Bones of Xenopus laevis, a freshwater species, and of other amphibians, reptiles, and mammals contained numerous osteocytes and a well-developed lacunocanalicular system. The present study indicates that development of the osteocyte lacunocanalicular system differs between teleost fishes and land vertebrates, but this pattern is not directly related to aquatic habitat.

Effects of aging and sarcopenia on tongue pressure and jaw-opening force

Aging and sarcopenia reduce not only body strength, but also the strength of swallowing muscles. We examined how aging and sarcopenia affect tongue pressure and jaw‐opening force.

Retention of bone strength by feeding of milk and dairy products in ovariectomized rats: involvement of changes in serum levels of 1alpha, 25(OH)2D3 and FGF23

The current study compared the effects of milk, yogurt or whey on the bone strength, body composition and serum biomarkers. Forty 12-week-old female Sprague-Dawley rats were ovariectomized (OVX), and another nine rats received a sham operation (Sham-Cont). After a 1-week recovery period, the OVX rats were divided into four dietary groups: OVX-control group (OVX-Cont), 17% skimmed milk powder diet group (OVX-Milk), 17% powdered fermented milk diet group (OVX-Yogurt) and 12% whey powder and 6% whey protein extract diet group (OVX-Whey) (n=10 in each group). The protein, nitrogen, fat, calcium and phosphorus contents of the experimental diets were adjusted to be similar to the control diet (AIN-93M). Eighty-four days after the beginning of the experimental diet, the total bone mineral density and bone mineral contents of lumbar vertebrae were significantly higher in the OVX-Milk and OVX-Whey groups than in the OVX-Cont group. Furthermore, the level of 1alpha, 25-dihydroxyvitamin D3 [1alpha, 25(OH)2D3] was significantly lower, while the serum level of FGF23 was significantly higher in the OVX-Milk, OVX-Yogurt and OVX-Whey groups than in the OVX-Cont group. These findings suggest that milk and the dairy products could improve bone metabolism in a postmenopausal animal model at least partly through changing the balance between 1alpha, 25(OH)2D3 and FGF23.

Dynamics of Swallowing Tablets during the Recovery Period following Surgery for Tongue Cancer

1.1. Objective: Medicinal tablets are sometimes difficult to swallow, even for healthy individuals. Accordingly, it is likely more difficult for patients to swallow tablets after oral surgery for tongue tumors. In this study, we aimed to investigate the dynamics of swallowing tablets in the recovery period following surgery for tongue tumors. 1.2. Methods: Two experiments were conducted (Experiment 1 and Experiment 2). In Experiment 1, 20 tongue cancer patients swallowed simulated tablets and underwent videofluoroscopic (VF) examination of swallowing before and after surgery. The ability or inability to pass the tablet to the esophagus and the number of swallowing attempts required to ingest the tablet were evaluated. In Experiment 2, 48 similar subjects swallowed thickened barium and simulated tablets and underwent VF examination of swallowing after surgery. The ability or inability to pass the tablet to the esophagus, the number of swallows required to ingest the tablet, the tablet position after the initial and the final swallowing reflexes, and the oral transit time and pharyngeal transit time for swallowing the thickened barium solution and simulated tablets were evaluated. 1.3. Results: After subtotal glossectomy, more subjects were unable to pass the tablet to the esophagus after surgery rather than before surgery. However, after surgery, patients needed more numbers of swallowing reflex attempts in order to successfully swallow tablets. Also, the tablets remained not only in the mouth, but also in the epiglottic vallecula and pyriform sinus. In the patients who could pass the tablet, the oral transit time of the thickened barium solution was shorter than in the patients who could not. 1.4. Conclusion: In cases of subtotal glossectomy, tablet intake should be avoided, particularly in the recovery phase, and VF or endoscopic evaluation of swallowing should be performed when tablets are prescribed. After tongue cancer surgery, patients should be recommended to make multiple swallowing attempts when swallowing tablets.

Relationship between jaw opening force and hyoid bone dynamics in healthy elderly subjects

Purpose This study aimed to examine the relationship between jaw opening force and hyoid bone dynamics and resting position in elderly individuals based on gender. Subjects and methods Subjects were 36 healthy elderly individuals aged ≥65 years without dysphagia (16 men and 20 women; mean age 75.5 years, range 65–88 years). Videofluorographic images during the swallowing of 10 mL of 40% (w/v) barium sulfate were obtained and the degrees of anterior, superior, and hypotenuse displacements of the hyoid bone and maximum/resting hyoid position were evaluated. Jaw opening force was measured three times using a jaw opening force sthenometer; the mean of these three measurements was used for analysis. Results In men, there was a positive correlation between jaw opening force and resting hyoid position and negative correlations among all the degrees of anterior, superior, and hypotenuse displacements of the hyoid bone. In women, there was no statistically significant correlation between jaw opening force and any of the measurement items. There was no statistically significant correlation between jaw opening force and maximum hyoid position in either men or women. Conclusion Our findings suggest that low jaw opening force leads to low resting hyoid position only in elderly men, and a lower hyoid position in healthy elderly men results in a larger total amount of hyoid displacement during swallowing. Moreover, a maximum hyoid position in healthy individuals of either gender does not differ depending on their jaw opening force.

Lighting up Skeletal Biology by Fluorescent Imaging

Abstract Skeletal development and bone homeostasis are dynamic but coordinated cellular process that involves proliferation, migration and differentiation. Molecular biology and genome science promoted this realm of biomedical science by elucidating cell lineages and essential molecules and their interactions. Fluorescence live imaging has made it possible to quantitatively analyze multi-cellular processes in 4 dimensions, thus providing coherent understanding of distinct levels of description from molecular levels to the tissue, organ and organism. Application of this approach has given further insight into and comprehension of the dynamic process of, not a mere description of the molecular hierarchy, skeletal biology. In this review paper, how fluorescent imaging has shed new light on the skeletal biology will be discussed. We introduce several current topics in the application of fluorescent imaging on skeletal patterning, morphometry of bone cells and cellular behavior in bone marrow.

Hox Genes, a Molecular Constraint for the Development and Evolution of the Vertebrate Body Plan

A set of Hox genes expressed during the embryonic process presents a crucial system to set up the body plan in animal phyla. Current systematic approaches, such as bio-imaging, epigenetic regulation and phylogenetic genome comparison, illuminated new comprehensive insights into Hox genes as an evolutionary constraint of the vertebrate body plan, which provides a novel counter-view to give further insights into the evolution and development of the craniofacial and dental systems as non-Hox systems.

High-speed jaw-opening exercise in training suprahyoid fast-twitch muscle fibers

Purpose This study was aimed to examine the effectiveness of a high-speed jaw-opening exercise, which targets the contraction of fast-twitch muscle fibers, in improving swallowing function. Subjects and methods Twenty-one subjects (mean age 74.0±5.7 years) with dysphagia-related symptoms, such as coughing or choking during eating, performed the exercise. None of the included subjects had neurological symptoms or history of surgery that could cause significant dysphagia. All subjects took regular meals, and maintained independent activities of daily life. The exercise schedule consisted of 3 sets of 20 repetitions each of rapid and maximum jaw-opening movement with a 10-second interval between sets. The exercise was performed twice daily for 4 weeks. Results Following the intervention, there was a significant increase in the vertical position of the hyoid bone at rest. Furthermore, during swallowing, the elevation of the hyoid bone and the velocity of its movement and esophageal sphincter opening increased significantly while the duration of the hyoid elevation and the pharyngeal transit time reduced significantly. Conclusions Our results demonstrated that high-speed jaw-opening exercise resulted in increased elevation velocity of the hyoid bone during swallowing, indicating its role in effectively strengthening the fast-twitch muscle fibers of suprahyoid muscles. Furthermore, since the rest position of the hyoid bone appeared to have improved, this exercise may be especially useful in elderly individuals with a lower position of the hyoid bone at rest and those with decreased elevation of the hyoid bone during swallowing, which are known to be associated with an increased risk of aspiration.

Age-related declines in the swallowing muscle strength of men and women aged 20–89 years: A cross-sectional study on tongue pressure and jaw-opening force in 980 subjects

Swallowing muscle strength weakens with aging. Although numerous studies have investigated tongue pressure (TP) changes with age, studies on jaw-opening force (JOF), an indicator of suprahyoid muscle strength, are lacking. We investigated differences between age-related declines in TP and JOF in a cross-sectional study of 980 healthy and independent participants (379 men, 601 women) without dysphagia. Hand grip strength (HGS), TP, and JOF were compared among decade-based age groups in multiple comparison analyses with post-hoc tests and effect size calculated. Participants were divided into adult (20 s-50 s) and elderly groups (60 s-80 s); within each group, Pearson correlations between age and muscle strength indices were evaluated. TP started to significantly decline in the 60 s and 50 s for men and women (p < .01, medium effect size and p < .05, small effect size, respectively); HGS also declined at these ages (men: p < .01, women: p < .01, medium effect size). JOF started to significantly decline in men in their 80 s (p < .01, large effect size), but remained unchanged in women. In the elderly group, all measurements declined with age more sharply in men (HGS: r = -0.56, TP: r = -0.63, JOF: r = -0.13) than in women (HGS: r = -0.38, TP: r = -0.49, JOF: r = -0.003). TP declined more steeply than did JOF. Thus, the age related-decline in TP was similar to that of the HGS, but not the JOF. The results reveal that different patterns exist in the age-related decline in swallowing muscle strength, and suggest that maintenance of JOF might contribute to safe swallowing in healthy elderly individuals.