Effect of surface stiffness in initial adhesion of oral microorganisms under various environmental conditions.

Biofilms are three-dimensional structures formed as a result of microorganism's adhesion on a biotic or abiotic surface. Once a biofilm is established, it is onerous to eradicate it or kill the pathogens therein. Thus, targeting the microbial adhesion process, the initial stage of biofilm formation, is a reasonable approach to avoid challenges associated with subsequently formed biofilms. While many properties of interacting material that play significant roles in initial bacterial adhesion have been widely studied, the effect of surface stiffness on bacterial adhesion was relatively underexplored. In this study, we aimed to investigate the effect of surface stiffness on the adhesion of microbial species found in the oral cavity by employing representative oral bacteria, Streptococcus mutans and Streptococcus oralis, and the fungus, Candida albicans. We compared the adhesion behavior of these species alone or in combination toward various surface stiffness (0.06 - 3.01 MPa) by assessing the adhered and planktonic cell numbers at an early (4 h) adhesion stage under various carbon sources and the presence of conditioning film. Our data revealed that in general, a higher amount of microbial cells adhered to softer PDMS surfaces than stiffer ones, which indicates that surface stiffness plays a role in the adhesion of tested species (either single or co-cultured). This pattern was more obvious under sucrose conditions than glucose + fructose conditions. Interestingly, in monospecies, saliva coating did not alter the effect of surface stiffness on S. mutans adhesion while it diminished S. oralis and C. albicans adhesion. However, in the multispecies model, saliva coating rendered the percentage of all adhered microbes to varied PDMS not distinct. The data provide new insights into the role of surface stiffness on microbial mechanosensing and their initial adhesion behavior which may set a scientific foundation for future anti-adhesion strategies.

Insights into the Role of Circadian Rhythms in Bone Metabolism: A Promising Intervention Target?

Numerous physiological processes of mammals, including bone metabolism, are regulated by the circadian clock system, which consists of a central regulator, the suprachiasmatic nucleus (SCN), and the peripheral oscillators of the BMAL1/CLOCK-PERs/CRYs system. Various bone turnover markers and bone metabolism-regulating hormones such as melatonin and parathyroid hormone (PTH) display diurnal rhythmicity. According to previous research, disruption of the circadian clock due to shift work, sleep restriction, or clock gene knockout is associated with osteoporosis or other abnormal bone metabolism, showing the importance of the circadian clock system for maintaining homeostasis of bone metabolism. Moreover, common causes of osteoporosis, including postmenopausal status and aging, are associated with changes in the circadian clock. In our previous research, we found that agonism of the circadian regulators REV-ERBs inhibits osteoclast differentiation and ameliorates ovariectomy-induced bone loss in mice, suggesting that clock genes may be promising intervention targets for abnormal bone metabolism. Moreover, osteoporosis interventions at different time points can provide varying degrees of bone protection, showing the importance of accounting for circadian rhythms for optimal curative effects in clinical treatment of osteoporosis. In this review, we summarize current knowledge about circadian rhythms and bone metabolism.

Randomized trial assessing the impact of a musculoskeletal intervention for pain before participating in a weight management program.

PURPOSE: Obesity increases the risk of developing physical disability and pain. Persons with a body mass index (BMI) of 30 kg/m or more have an increased risk for osteoarthritis compared with those with a BMI between 25 and 29 kg/m. The purpose of this study was to examine the effect of treatment directed at reducing musculoskeletal pain on weight loss in obese subjects prior to participation in a 6-month weight management (WM) program. METHODS: Subjects (BMI > or = 30 kg/m; n = 54, female = 41, male = 13) with musculoskeletal pain, as assessed by a visual analog scale score of more than 5, were randomized to a physician musculoskeletal evaluation with treatment and physical therapy prior to participation in a 6-month WM program (intervention) or direct entry into the WM program (control) between November 10, 2003, and January 20, 2005. RESULTS: Seventy-six percent of subjects completed the study (intervention, n = 18 [67%]; control, n = 23 [85%], P = .10). The intervention group demonstrated a significant decrease in visual analog scale score after musculoskeletal therapy (2.3 +/- 1.8, P < .0001). Despite a reduction in pain levels in the intervention group compared with the control group at the start of the WM program, there were no significant differences between the groups in percentage weight loss (P = .80), body fat composition (P = .20), or BMI (P = .06), all significantly improved in both groups. CONCLUSIONS: Musculoskeletal and physical therapy intervention directed at decreasing musculoskeletal pain in obese individuals prior to participation in a WM program reduces reported musculoskeletal pain for those participants completing the program but does not significantly improve weight loss over 6 months, compared with individuals with comparable musculoskeletal pain who enter directly into a WM program.