RANKL+ senescent cells under mechanical stress: a therapeutic target for orthodontic root resorption using senolytics / 国际口腔科学杂志·英文版

In dentistry, orthodontic root resorption is a long-lasting issue with no effective treatment strategy, and its mechanisms, especially those related to senescent cells, remain largely unknown. Here, we used an orthodontic intrusion tooth movement model with an L-loop in rats to demonstrate that mechanical stress-induced senescent cells aggravate apical root resorption, which was prevented by administering senolytics (a dasatinib and quercetin cocktail). Our results indicated that cementoblasts and periodontal ligament cells underwent cellular senescence (p21+ or p16+) and strongly expressed receptor activator of nuclear factor-kappa B (RANKL) from day three, subsequently inducing tartrate-resistant acid phosphatase (TRAP)-positive odontoclasts and provoking apical root resorption. More p21+ senescent cells expressed RANKL than p16+ senescent cells. We observed only minor changes in the number of RANKL+ non-senescent cells, whereas RANKL+ senescent cells markedly increased from day seven. Intriguingly, we also found cathepsin K+p21+p16+ cells in the root resorption fossa, suggesting senescent odontoclasts. Oral administration of dasatinib and quercetin markedly reduced these senescent cells and TRAP+ cells, eventually alleviating root resorption. Altogether, these results unveil those aberrant stimuli in orthodontic intrusive tooth movement induced RANKL+ early senescent cells, which have a pivotal role in odontoclastogenesis and subsequent root resorption. These findings offer a new therapeutic target to prevent root resorption during orthodontic tooth movement.

Effects of regular green tea intake on body fat and arterial stiffness in young adults: A randomized intervention study / 体力科学

Green tea catechins are well known to be one of polyphenols, and its regular ingestion induces body fat reduction in obese individuals. Cocoa polyphenols of high-cocoa chocolate can also improve arterial stiffness. However, it is unclear whether green tea catechins improve body fat and arterial stiffness even in healthy young adults. Therefore, this study aimed to examine the effects of regular green tea intake on body fat and arterial stiffness in young adults. This randomized, controlled, parallel-group intervention study included 53 Japanese college students (mean age, 21.1 ± 0.1; men, n = 40; women, n = 13). They were randomly divided into three groups: control group (n = 14), intervention I group (n = 19), and intervention II group (n = 20). The participants ingested 500 ml/day of commercially available natural water (0 mg of catechin/day) or green tea (intervention I group, 200 mg of catechin/day; intervention II group, 400 mg of catechin/day) for 4 weeks. After 4 weeks of intervention period, no significant changes in body weight, body mass index, pulse wave velocity, and cardio-ankle vascular index were observed in all groups. However, body fat and carbon dioxide output significantly reduced only in the intervention II group. With the level of catechin concentrations increasing, significant decreasing trends were found in body fat changes and respiratory exchange ratio changes. Therefore, these findings suggest that four weeks of regular green tea intake would reduce body fat, but not arterial stiffness, in young adults.

The effects of Pokémon GO playing on daily steps: A retrospective observational study in Japanese male college students / 体力科学

This retrospective observational study aimed to examine the effects of playing Pokémon GO on daily steps of male college students. Twenty-five Japanese male college students (20 ± 1 years) were assigned to Control group (C, n = 11) or Pokémon GO group (P, n = 14) based on their playing Pokémon GO or not. Daily step levels were obtained from the health care app of Apple iPhone from September 2016 to October 2016. In P group, the data for the 4 weeks to determine baseline values and for the 4 weeks of playing Pokémon GO were analyzed. The steps data of C group were also analyzed in the same period of the total 8 weeks. There were no significant differences in steps at baseline level between both groups. In addition, no significant time-course changes in steps were observed in C group. In contrast, steps in P group significantly increased from baseline 8,368 ± 544 steps/day to week 1 10,028 ± 617 steps/day (P < 0.01). The changes in steps from baseline to week 1 were significantly greater in P group than in C group (1,671 ± 345 vs. -81 ± 582, P < 0.01). However, the increased steps returned to baseline level by week 2, and the values did not increase again. Therefore, our findings indicate that playing Pokémon GO increases daily steps only during one week in Japanese male college students.

An examination of a new walking method to fulfill the Physical Activity Reference in a shorter time / 体力科学

This study aimed to examine a new walking method to fulfill the Physical Activity Reference for Health Promotion in Japan in a shorter time, which can be performed as a non-exercise activity (NEA) such as walking during commuting. Eleven healthy subjects performed normal walking (NW) and knee-up walking (KU) for eight minutes without load (0%) and with loads of 5, 10, and 20% of body mass in a backpack carried on the back (NW-0, 5, 10, and 20; KU-0, 5, 10, and 20) on a treadmill at a speed of 5 km/h at 0% tilt. Oxygen uptake, blood lactate levels, and ratings of perceived exertion (RPE) were measured in the last two minutes of each walking stage. Metabolic equivalents (METs) were also calculated from the resultant oxygen uptake. METs in NW-20 and all weight conditions of KUs were significantly greater (P < 0.01) than those in NW-0 (3.8 ± 0.1 METs). RPE in both KU-10 and KU-20 was above 15 (i.e., indicating Hard). Blood lactate levels in the KU-20 (4.5 ± 0.7 mmol/L) were above the Onset of Blood Lactate Accumulation. On the other hand, NW-20, KU-0, and KU-5 were physical activity level of moderate- to vigorous- intensity that could be performed as a NEA. These data suggest that our new walking methods such as NW-20, KU-0, and KU-5 can satisfy the Physical Activity Reference in a shorter time rather than normal walking, and could be continuously performed in daily life.

Effects of a lifestyle intervention by the concurrent use of an activity monitor and Twitter on physical activity -A randomized intervention study- / 体力科学

This study aimed to clarify the effects of a lifestyle intervention by the concurrent use of an activity monitor and Twitter on daily physical activity. Twenty-one healthy males and females (37 ± 13 yrs) were randomly assigned to Normal intervention group (N group, n = 10) or Twitter intervention group (T group, n = 11). In both groups, the intervention period was 6 weeks. Participants in N group wore an activity monitor (Lifecorder EX). Meanwhile, participants in T group were asked to tweet about their daily steps or physical activity in addition to wearing an activity monitor, and also an observer read through the tweet from each participant and commented about physical activity. There were no significant differences in daily physical activity (<i>i.e</i>., steps and amount of physical activity (PA)) at week 1 between both groups. In addition, no significant time-course changes in steps and amount of PA were observed in N group. In contrast, steps in T group were gradually increased from week 1 8,542 ± 3,158 steps/day to week 6 12,700 ± 3,935 steps/day (P < 0.01). Amount of PA in T group was also gradually increased from week 1 2.5 ± 1.2 METs·hour/day to week 6 4.6 ± 2.3 METs·hour/day (P < 0.01). Therefore, these findings indicate that the lifestyle intervention by the concurrent use of an activity monitor and Twitter could effectively induce an increase in daily physical activity compared with the intervention using only an activity monitor.

Effects of a lifestyle intervention using an activity monitor with game functions on physical activity-A randomized crossover study- / 体力科学

This study aimed at clarifying the effects of a lifestyle intervention using an activity monitor with game functions on daily physical activity. A 12-week randomized crossover study was conducted in 23 healthy volunteers (31 ± 11 yrs). The subjects were randomly assigned to Group A (a 6-week game intervention and then a 6-week normal intervention) and Group B (a 6-week normal intervention and then a 6-week game intervention). In the game intervention period (G), the subjects wore two different activity monitors, namely a normal activity monitor (Lifecorder EX) and an activity monitor with game functions (Yuuhokei). On the other hand, in the normal intervention period (N), the subjects wore only a normal activity monitor. Daily steps were significantly higher in the G than in the N (G: 10417 ± 2358 vs. N: 8744 ± 2180 steps/day, P < 0.001). Amount of physical activity (<i>i.e.</i>, daily total METs · hour = Ex/day) at the intensity of 3 METs or more was significantly higher in the G than in the N (G: 3.1 ± 0.9 vs. N: 2.4 ± 0.8 Ex/day, P < 0.001). Our results indicate that the lifestyle intervention using an activity monitor with game functions would more effectively increase daily physical activity such as steps and physical activity amount, than a normal intervention using an activity monitor. These findings therefore have important implications for reaching more easily the goals (<i>i.e.</i>, 23 Ex/week or 10,000 steps/day) and the use of an activity monitor with game functions in the field of exercise or physical activity instructions.