Effects of treadmill exercise on the LiCl-induced conditioned taste aversion in rats.

Studies have shown that exercise can enhance learning and memory. Conditioned taste aversion (CTA) is an avoidance behavior induced by associative memory of the taste sensation for something pleasant or neutral with a negative visceral reaction caused by the coincident action of a toxic substance that is tasteless or administered systemically. We sought to measure the effects of treadmill exercise on CTA in rats by investigating the effects of exercise on acquisition, extinction and spontaneous recovery of CTA. We made two groups of rats: an exercise group that ran on a treadmill, and a control group that did not have structured exercise periods. To condition rats to disfavor a sweet taste, consumption of a 0.1% saccharin solution in place of drinking water was paired with 0.15M LiCl (2% body weight, i.p.) to induce visceral discomfort. We measured changes of saccharin consumption during acquisition and extinction of CTA. The exercise and no-exercise groups both acquired CTA to similar levels and showed maximum extinction of CTA around 6 days after acquisition. This result indicates that exercise affects neither acquisition nor extinction of CTA. However, in testing for preservation of CTA after much longer extinction periods that included exercise or not during the intervening period, exercising animals showed a significantly lower saccharin intake, irrespective of having exercised or not during the conditioning phase of the trial. This result suggests that exercise may help to preserve aversive memory (taste aversion in this example) as evidence by the significant spontaneous recovery of aversion in exercising animals.

Relationship between masticatory ability and physical performance in community-dwelling edentulous older adults wearing complete dentures.

OBJECTIVE: This study aimed to elucidate the association between masticatory ability and physical performance in community-dwelling edentulous older adults wearing complete dentures. BACKGROUND: Physical performance parameters are significant predictors of decreased activities of daily living. Previous studies have shown the relationships between oral conditions and these parameters. Here, we focused on complete denture wearers. METHODS: Two hundred and ten edentulous adults aged ≥65 years and wearing complete dentures were enrolled. The following oral conditions were examined: masticatory ability measured by colour-changing chewing gum, number of foods considered chewable, pain when using dentures and denture base fit. Handgrip strength (HG) and one-leg standing time with eyes open (OLST) were used to evaluate muscle strength and static balance. Spearman's rank correlation coefficients were calculated to examine the correlations between oral conditions and physical performance. Forward stepwise linear regression models were applied with each physical performance parameters as the dependent variable and oral conditions as the independent variable. RESULTS: The women did not show significant correlations between oral conditions and the physical performance. In men, significant and positive correlations were found between the number of chewable foods and HG, and between the colour scores and OLST. The significant correlation between the colour scores and OLST was still noted in the stepwise liner regression analysis after adjusting for demographic, social and medical conditions, and other oral conditions. CONCLUSION: In Japanese elderly edentulous men wearing complete dentures, masticatory ability evaluated as the mixing ability may be associated with static balance.

Analysis of moment structures for assessing relationships among perceived chewing ability, dentition status, muscle strength, and balance in community-dwelling older adults.

OBJECTIVE: The aim of this study was to assess relationships among perceived chewing ability, dentition status, muscle strength and balance in community-dwelling older adults using analysis of moment structures (Amos). BACKGROUND: Physical performance parameters such as muscle strength and balance can predict the future onset of disabilities in activities of daily living among older adults. In this context, elucidation of the relationships among oral conditions and physical performance parameters is necessary. MATERIALS AND METHODS: Data on occlusal contact patterns of natural teeth (OPNT), self-assessed masticatory ability (mastication), body mass index (BMI), handgrip strength (HG) and one-leg standing time with eyes open (OLST) were collected from 501 independently living adults aged 65-74 years. The relationships among these parameters were analysed using Spearman's rank correlation coefficients and Amos. RESULTS: Subjects of both genders showed significant correlations among OPNT, mastication, HG and OLST, evaluated using Spearman's rank correlation coefficients. For each Amos model, the goodness-of-fit statistic indicated a good level of fit. In both men and women, OPNT was significantly related to mastication, and mastication was related to HG but not to OLST. OPNT was related to neither HG nor OLST in women and was related to OLST but not HG in men. CONCLUSION: The findings observed in this study present a possible importance of dental status and perceived chewing ability for the onset of disability by influencing physical performance in community-dwelling older adults.

Relationship between subjective assessment of oral health and medical expenses in community-dwelling elderly persons.

OBJECTIVES: The increasing medical expenses of elderly persons in Japan's rapidly ageing society have become a major concern. It is therefore important to elucidate the factors associated with such escalation. Here, we focused on the relationship between subjective self-assessment of oral health, as an index of general health, and medical expenses (excluding dental repair) under the hypothesis that oral health contributes to general medical expenses. Several studies have shown that oral health status is correlated with general health status among elderly persons. We speculated that oral health status might show a relation with medical costs among elderly persons. However, few studies have investigated this relationship to date. MATERIALS AND METHODS: Participants were 259 elderly subjects (range: 65-84 years; 120 men, 139 women) residing independently. Subjective assessment of oral health was evaluated by their responses ('Good', 'Not good' and 'Not at all good') on a survey questionnaire. The correlation between subjective assessment of oral health and medical expenditure was analysed using Spearman's rank method, the Mann-Whitney U-test and the Kruskal-Wallis test. Medical expenses were used as the dependent variable in multinomial logistic regression analysis with background and intraoral factors as independent variables. RESULTS: A slight yet statistically significant correlation was observed between subjective assessment of oral health and outpatient treatment fees. CONCLUSION: The findings revealed that subjective assessment of oral health is significantly and independently related to the medical expenses of community-dwelling elderly persons after adjusting for social background, living environment and physical factors.

Relationships between oral conditions and physical performance in a rural elderly population in Japan.

OBJECTIVES: To show relationships between oral conditions and physical performance in the elderly living independently. METHODS: A total of 821 persons participated. Data on background factors and self-assessed masticatory ability were collected by means of questionnaires. An intraoral examination was performed to examine the pattern of occluding pairs of natural teeth. Handgrip strength and one-leg standing time with eyes open were measured. Step-wise linear regression models were conducted with muscle strength or one-leg standing time as the dependent variables; the pattern of occluding pairs and self-assessed masticatory ability as the principal independent variables. RESULTS: The self-assessed masticatory ability was retained in the final model of the step-wise regression for the handgrip strength, and significant relationships were established in the participants aged 65-74, but the pattern of occluding pairs was not retained. The pattern of occluding pairs, and the self-assessed masticatory ability were retained in the final models for the one-leg standing time, and significant relationships were shown here. CONCLUSION: The self-assessed masticatory ability may be significantly related to muscle strength and static balance function, and the pattern of occluding pairs may be significantly related to the static balance function, particularly in the elderly aged 65-74.

Expression of cys-cys chemokine ligand 21 on human gingival lymphatic vessels.

The cys-cys (C-C) chemokine ligand 21 is a member of the C-C chemokines that constitute a group of heparin-binding cytokines with a pattern of four or six conserved cysteines. The CCL21 is known to be expressed in secondary lymphoid tissues, however it has rarely been reported for the expression on peripheral lymphatic vessels in somatic tissue. Here we investigated the expression of CCL21 on lymphatic vessels identified by anti-desmoplakin in uninflamed and inflamed human gingiva. In uninflamed tissue the expression of CCL21 was detected on lymphatic vessels in gingiva. In uninflamed gingiva the expression of CCL21 was detected on all lymphatic capillaries of the mucosal connective tissue papillae. There were two types of collecting lymphatic vessels in the lamina propria mucosae expressing CCL21 strongly or very weakly. In inflamed gingiva no expression of CCL21 was detected on lymphatic vessels. In all tissue sections no blood vessels expressing CCL21 were observed. These results may suggest that the expression of CCL21 is predominantly induced in the peripheral lymphatic endothelium of the uninflamed mucosal microcirculation, and that under inflamed conditions a reduction of CCL21 occurs in lymphatic endothelium.

Expression of Toll-like receptors 2 and 4 on human intestinal lymphatic vessels.

The Toll-like receptor (TLR) is a part of the innate immune system sensing pathogen-associated molecular patterns (PAMPs). Recently, TLRs 2 and 4 have been demonstrated for the ligand engagements, which result in the induction of cytokines. Here we investigated the expression of TLRs 2 and 4 on lymphatic vessels producing cys-cys chemokine ligand 21 (CCL21) in the human small intestine. The specificity of antibodies to TLRs was tested on a human monocyte leukemia cell line, umbilical vein endothelial cells (HUVEC), and periodontal ligament fibroblasts (PDLF) with the examination for the TLR gene expression by the reverse transcription-polymerase chain reaction (RT-PCR), and lymphatic vessels were identified by antibodies for platelet-endothelial cell adhesion molecule-1 (PECAM-1) and desmoplakin. The expression of CCL21 was not clearly detected on collecting lymphatic vessels in the submucosa while it was generally observed on the central lacteals of villi and lymphatic capillaries in the lamina propria mucosae. The reaction of antibodies to TLRs 2 and 4 was also not clearly detected on collecting lymphatic vessels in the submucosa and central lacteals of villi, but generally observed on lymphatic capillaries expressing CCL21 in the lamina propria mucosae of tissue where the expression of CCL21 and TLRs was not clearly observed in blood vessels. These may suggest that the expression of CCL21, and TLRs 2 and 4 is predominantly induced in the peripheral lymphatic endothelium of the small intestinal microcirculation. The lymphatic endothelium may contribute to allow dendritic cells to home into secondary lymphoid tissue through the expression of TLRs, the ligand engagements of which result in the induction of chemokines.