Increased hydrostatic pressure induces nuclear translocation of DAF-16/FOXO in C. elegans.

Mechanical stimulation is well known to be important for maintaining tissue and organ homeostasis. Here, we found that hydrostatic pressure induced nuclear translocation of a forkhead box O (FOXO) transcription factor DAF-16, in C. elegans within minutes, whereas the removal of this pressure resulted in immediate export of DAF-16 to the cytoplasm. We also monitored DAF-16-dependent transcriptional changes by exposure to 1 MPa pressure for 5 min, and found significant changes in collagen and other genes in a DAF-16 dependent manner. Lifespan was markedly prolonged with exposure to cyclic pressure treatment (1 MPa once a day for 5 min from L1 larvae until death). Furthermore, age-dependent decline in locomotor activity was suppressed by the treatment. In contrast, the nuclear translocation of the yes-associated protein YAP-1 was not induced under the same pressure conditions. Thus, moderate hydrostatic pressure improves ageing progression through activation of DAF-16/FOXO in C. elegans.

Relationship between head position and the muscle hardness of the masseter and trapezius muscles: a pilot study.

The purpose of this study was to examine the hardness of the masseter and trapezius muscles at various head positions and to explore the relationship of these two muscles to each other in terms of their respective levels of muscle hardness at different head positions. Twenty-two asymptomatic male subjects participated in this study. Using a hand-held hardness meter, muscle hardness was first measured in a relaxed position as a baseline. The subjects were then asked to assume five deviated head positions, and the muscle hardness was measured again. The data obtained at each deviated head position were compared to those at baseline. In addition, the subjects were asked to maintain a five minute sustained anterior flexion of the head, and muscle hardness was also measured and compared to the baseline. As a result, there was a significant increase in muscle hardness at the point of the whole trapezius with 30-degree anterior flexion, while there was a significant decrease at the point of the right masseter. A significant increase in hardness was seen in the upper trapezius muscle in conjunction with right side bending and in the right upper trapezius muscle on left side bending. Also, a significant decrease in hardness was observed in the right masseter with right side bending. With reference to the axial rotation, there was a significant increase in hardness in the upper right trapezius muscle upon right axial rotation. Moreover, there was a significant increase in the muscle hardness in the whole trapezius after the five minute anteriorly sustained head task. This study provides evidence that deviated head positions lead to an increase in hardness of the trapezius muscle. The data also revealed the simultaneous occurrence of the elevation of muscle hardness in the upper trapezius muscle and the decrease in muscle hardness in the masseter muscle associated with right side bending and anterior flexion.

Effect of short-term use of a centric occlusion stabilization oral appliance on sensory and pain perception thresholds in the cervically innervated area: a pilot study.

This preliminary study was done to determine the effect of short-term use of a centric occlusion stabilization oral appliance with regard to noxious and sensory perception in the upper extremities. The subjects consisted of 22 asymptomatic females, and the experiments were performed on two separate days within the same week, with the days randomly assigned as either appliance-wearing or nonappliance-wearing days. For each experimental day, cool sensation, warm sensation, cold-induced pain and heat-induced pain were measured using a computer-based quantitative testing device, and these thresholds were compared between the experimental days with or without the oral appliance. We found that during the experimental day wearing an oral appliance, subjects had significantly higher thresholds for warm sensation and heat-induced pain. There was no statistical difference between the testing days in cool sensation or cold-induced pain thresholds. These findings indicate that short-term wearing of a centric occlusion stabilization oral appliance may inhibit some noxious and sensory inputs from cervically innervated structures, which are primarily served by unmyelinated C fibers, and that oral appliances may be appropriate for the treatment of painful cervical disorders.

Changes in sensory and pain perception thresholds after linear polarized near-infrared light radiation in the trigeminal region.

Linearly polarized light in the near-infrared portion of the spectrum has recently been associated with a variety of musculoskeletal disorders including temporomandibular disorders. The purpose of this study was to determine whether short-term linearly polarized near-infrared light radiation in the trigeminal region affects sensory and pain perception thresholds in the trigeminally mediated region and in the cervically mediated region of normal subjects. Thirty-five normal female volunteers participated in this study. Each subject received an 8-minute course of irradiation in the right cheek, and sensory/nociceptive perception thresholds were compared before and immediately after the irradiation in the right cheek and the right forearm. As a result, this study demonstrated a significant elevation of the heat-induced pain threshold in both regions and a tendency for the warm sensation threshold to elevate in the cervical region. In addition, a significant increase in vibratory sensitivity was observed in the trigeminal region. In conclusion, our results provided additional evidence that the warming sensation has a negative feedback influence on heat pain intensity in humans, and provides a theoretical basis for the application of linear polarized near-infrared light radiation to the trigeminal region.

Muscle hardness characteristics of the masseter muscle after repetitive muscle activation: comparison to the biceps brachii muscle.

The purpose of this study was to compare hardness characteristics of the masseter muscle to those of the biceps brachii muscle during repetitive muscle movements. Seventeen asymptomatic female subjects participated in this study. Each subject, on separate days, undertook a 5-minute unilateral chewing gum task on the right side and a 5-minute flexion-extension exercise on the right hand with a 2kg dumbbell. Using a handheld hardness meter, muscle hardness was measured in the right masseter and in the biceps brachii muscle at eight time points (before the task, immediately after the task, and at 1, 3, 5, 10, 30, and 60 minutes after the task), and the data obtained before and after the task on each muscle were compared. Comparisons of the normalized data were also performed between the two muscles at each time point. As a result, a significant increase in muscle hardness was seen at 1 minute after the task in the biceps brachii muscle (p=0.0093). In contrast, the masseter muscle showed a tendency to lower hardness, with the lowest point of hardness occurring at 10 minutes after the task (p = 0.0160). Between the two muscles, there was a difference in the normalized data immediately after the task, and at 1, 5, and 10 minutes after the task (0.01