Jaw muscle activity patterns in women with chronic TMD myalgia during standardized clenching and chewing tasks.

Objective: To examine jaw muscle activity of women with chronic temporomandibular myalgia (mTMD). It was hypothesized that mTMD patients had a different masticatory muscle activity, increased work during isometric clenching, and a reduced chewing frequency as compared to TMD-free subjects.Methods: The electromyographic (EMG) activity of temporalis anterior (TA) and masseter (MM) of 27 women with mTMD and 18 TMD-free women was recorded during clenching tasks and while chewing. EMG indices comparing the activity of paired jaw muscles were computed.Results: Women with TMD myalgia had greater muscular work than controls (p = 0.025). The activity of TA and MM were similar between right and left sides in both groups. mTMD patients had a greater activity of MM than TA (p = 0.028). No between-groups differences were found in chewing rate.Conclusion: Women with mTMD showed an abnormal recruitment of the jaw-closing muscles during functional tasks, which may predispose to further tissue injury.

"Pressure pain threshold over masticatory muscles and temporomandibular joint in patients with juvenile idiopathic arthritis".

BACKGROUND: Juvenile idiopathic arthritis (JIA) is an autoimmune, chronic, inflammatory joint disease, affecting children and adolescents. Patients with JIA may have pain and fatigue in muscles. There are not studies evaluating the pressure pain thresholds (PPTs) of both masticatory muscles and temporomandibular joint (TMJ) in patients with JIA. OBJECTIVE: This study aimed to investigate PPTs of masticatory muscles and TMJ in subjects with JIA. METHODS: Fifty-one JIA patients and fifty-two healthy subjects were recruited. JIA group was assessed for with a standardised clinical examination for temporomandibular disorders. In all subjects, the PPT was evaluated in the following sites: anterior temporalis (AT) and masseter (MM) muscles, TMJ and thenar (TH) eminence. Comparisons between groups were assessed with unpaired t test and ANOVA (P < .05). RESULTS: Pressure pain thresholds were significantly lower among JIA patients compared with controls (P < .001) for all analysed sites. The presence of TMJ pain at palpation was significantly associated with a lower PPT at TMJ (P = .031). CONCLUSIONS: Patients with JIA have generally lowered pain threshold to mechanical stimulus, which suggests an effect of JIA on nocicepton-modulating processes.

Evaluation of masticatory muscle activity in patients with unilateral posterior crossbite before and after rapid maxillary expansion.

Objectives: The relationship between unilateral posterior crossbite (UPCB) and the possible asymmetric activation of the jaw muscles in children is still under debate. This study aimed at evaluating the jaw muscle activity of children with UPCB before and after rapid maxillary expansion (RME) by means of surface electromyography and a standardized sampling protocol. Subjects and methods: Twenty-nine children with UPCB (UPCB-group, mean age 9.6 ± 1.6 years) and 40 UPCB-free controls (Control-group, 10.5 ± 1.1) were recruited. The activity of the left and right anterior temporalis (AT) and superficial masseter muscles (MM) was recorded during maximum voluntary clenching and a chewing task (T0). In the UPCB-group, data were collected, also, after the correction of the UPCB with RME (T1) and 6 months later (T2), without any further treatment. Electromyographic indices comparing the activity of paired muscle were computed via software to estimate the extent of asymmetric AT and MM activity. Paired and unpaired t-test or Wilcoxon-signed rank and Mann-Whitney U test, ANOVA or Friedman test and chi-squared test were used in the statistical analysis. Results: Both groups presented with asymmetric activity of the muscles, which did not differ between groups (T0, all P > 0.05). The treatment determined a decrease in muscular activity (T1, P = 0.040), and a more asymmetric pattern of muscle activation during chewing (T1, P = 0.040), which returned similar to baseline values at T2 (all P > 0.05). Conclusions: UPCB does not contribute to an asymmetric activation of AT and MM during functional tasks. The treatment of UPCB by RME did not determine a more symmetric activity of the assessed muscles.

Low Erythrocyte Levels of Proteasome and Acyl-Peptide Hydrolase (APEH) Activities in Alzheimer's Disease: A Sign of Defective Proteostasis?

Alzheimer's disease (AD) is a progressive, multifactorial neurodegenerative disorder that is the main cause of dementia. To date, there are no definitive diagnostic tests that can predict or assess onset and progression of the disease. Blood biomarkers for AD are being sought for many years but their identification remains a challenging task. In this study, we investigated the potential relationship between AD and levels of acyl-peptide hydrolase (APEH) and proteasome in erythrocyte samples of 52 participants (26 AD and 26 cognitively healthy controls). A statistically significant decrease in proteasome and exopeptidase/endopeptidase APEH activities was found in AD samples compared to those of healthy controls. Moreover, in contrast to what was observed for proteasome transcripts, APEH activities reduction in AD patients was unrelated to its gene expression levels, suggesting the occurrence of posttranslational modifications or the expression of endogenous inhibitors that might impair enzyme activity. These preliminary data further support a relationship between the APEH-proteasome system and AD molecular players, providing the first evidence of its potential use as a novel blood-based indicator for the routine detection of AD.