Development of a tannic acid- and silicate ion-functionalized PVA-starch composite hydrogel for in situ skeletal muscle repairing.

The repair capacity of skeletal muscle is severely diminished in massive skeletal muscle injuries accompanied by inflammation, resulting in muscle function loss and scar tissue formation. In the current work, we developed a tannic acid (TA)- and silicate ion-functionalized tissue adhesive poly(vinyl alcohol) (PVA)-starch composite hydrogel, referred to as PSTS (PVA-starch-TA-SiO32-). It was formed based on the hydrogen bonding of TA to organic polymers, as well as silicate-TA ligand interaction. PSTS could be gelatinized in minutes at room temperature with crosslinked network formation, making it applicable for injection. Further investigations revealed that PSTS had skeletal muscle-comparable conductivity and modulus to act as a temporary platform for muscle repairing. Moreover, PSTS could release TA and silicate ions in situ to inhibit bacterial growth, induce vascularization, and reduce oxidation, paving the way to the possibility of creating a favorable microenvironment for skeletal muscle regeneration and tissue fibrosis control. The in vivo model confirmed that PSTS could enhance muscle fiber regeneration and myotube formation, as well as reduce infection and inflammation risk. These findings thereby implied the great potential of PSTS in the treatment of formidable skeletal muscle injuries.

Effects of vitamin D and/or calcium intervention on sleep quality in individuals with prediabetes: a post hoc analysis of a randomized controlled trial.

PURPOSE: The aim of this study was to evaluate the effects of vitamin D and/or calcium supplementation on sleep quality in individuals with prediabetes. METHODS: A 24-week randomized controlled trial (RCT) was conducted in a 212 Chinese population with prediabetes. Participants were randomly assigned to four groups: vitamin D + calcium group (1600 IU/day + 500 mg/day, n = 53), vitamin D group (1600 IU/day, n = 54), calcium group (500 mg/day, n = 51), and control group (placebo, n = 54). The Pittsburgh Sleep Quality Index (PSQI) was used as the primary outcome to assess sleep quality. Questionnaires and fasting blood samples were collected at baseline and post-intervention for demographic assessment and correlation index analysis. RESULTS: After a 24-week intervention, a significant difference was observed in serum 25(OH)D concentration among the four groups (P < 0.05), and the total PSQI score in vitamin D + calcium group was lower compared to the preintervention levels. Subgroup analyses revealed improved sleep quality with calcium supplementation (P < 0.05) for specific groups, including women, individuals with a low baseline 25(OH)D level (< 30 ng/mL), and individuals in menopause. Moreover, correlation analysis revealed a negative correlation between the extent of change in sleep efficiency scores before and after the calcium intervention and the degree of change in insulin efficiency scores (r = - 0.264, P = 0.007), as well as the magnitude of change in islet beta cell function (r = - 0.304, P = 0.002). CONCLUSIONS: The combined intervention of vitamin D and calcium, as well as calcium interventions alone, exhibits substantial potential for improving sleep quality in individuals with prediabetes. CLINICAL TRIAL REGISTRATION: The trial was registered in August 2019 as ChiCTR190002487.

Local stress analysis of blunt V-notches using the digital gradient sensing method.

In this study, the digital gradient sensing (DGS) method is extended to determine the local stress fields at the blunt V-notch tip. Completely analytical expressions for angular deflections of light beams in the vicinity of the blunt V-notch tip are deduced based on Filippi's stress equation. Under plane stress conditions, the patterns of angular deflection related to two orthogonal stress gradients are theoretically plotted, and the effects of notch angle and notch radius are synthetically investigated, respectively. New procedures for the evaluation of local stress components and generalized notch stress intensity factor (NSIF) are presented using the experimental patterns of angular deflection contours. The NSIF values at the blunt V-notch tip in polymer materials with different geometric parameters under three-point-bend loading conditions are extracted from the DGS measurements. A good agreement is observed between the experimental data and the finite element simulations, which can verify the effectiveness and accuracy of the proposed DGS method.