Injectable chitosan/xyloglucan composite hydrogel with mechanical adaptivity and endogenous bioactivity for skin repair.

Delayed or chronic wound healing is one of severe clinical issues. Developing scaffold materials capable of supporting cells and inducing tissue regeneration remains a challenge. Here, a polysaccharide-based hydrogel is constructed for promoting full-thickness skin wound healing in mouse model. The engineering hydrogel consists of a dynamic crosslinking network formed by the Schiff base reaction between aldehyde-containing xyloglucan and methacrylated chitosan. Its reversible gel-sol-gel transition upon shearing force is highly beneficial to completely cover and fill irregular wound shape. The second covalent cross-linking network achieved by photo-initiated polymerization offers a feasible way to tune the mechanical property of hydrogel after injection, with an ideal mechanical adaptivity for clinical application. Remarkably, both in vitro and in vivo evaluations demonstrate that the hydrogel with endogenously bioactive galactoside units can promote cell spheroid formation and accelerate wound healing by expediting re-epithelialization, collagen deposition, angiogenesis as well as the formation of hair follicles.

Architecting Lignin/Poly(vinyl alcohol) Hydrogel with Carbon Nanotubes for Photothermal Antibacterial Therapy.

With the development of antimicrobial resistance, rapid and effective killing of bacteria is required for infected wound healing after skin trauma. Herein, we reported a one-pot reaction strategy to prepare a composite hydrogel with antibacterial activity through high-efficiency photothermal therapy. We take poly(vinyl alcohol) as the matrix, and lignin-derived from biomass was introduced into the hydrogel to increase the tensile strength of the prepared hydrogel to 108.58 kPa, and the elongation at break reaches 200.8%. The electrostatic interaction between lignin and chitosan enhanced the reactivity of lignin. Carbon nanotubes endow the hydrogel with photothermal antibacterial activity that can kill more than 97% of either Escherichia coli or Staphylococcus aureus within 5 min, avoiding the problem of bacterial resistance. Experimental evaluation on mice showed that the hydrogel could effectively promote wound healing of full-thickness skin defects. The hydrogels with good mechanical properties, antioxidant activity, and excellent photothermal antibacterial ability show good potential to repair the damaged tissue and are expected to be used in the clinical transformation of wound dressing.

Effect of pedicle-screw rod fixation on oblique lumbar interbody fusion in patients with osteoporosis: a retrospective cohort study.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: To investigate the radiological and clinical outcomes of patients with or without pedicle-screw rod fixation (PSRF) in OLIF surgery. METHODS: Between June 2017 and December 2019, 66 consecutive patients who underwent OLIF surgery at two centers were divided into stand-alone and combined groups according to whether or not PSRF was used. Imaging and clinical data were collected preoperatively, postoperatively, 3 and 6 months postoperatively, and at the last follow-up. Related coefficient and multiple linear regression analysis was used to detect the influencing factors of cage subsidence (CS). RESULTS: There was a lower baseline BMD in the combined group (p = 0.005). The combined group showed superior VAS score at 3 months postoperatively, although there was no difference in long-term VAS and ODI scores between the two groups. The foraminal height (FH) of the two groups was comparable at preoperatively, postoperatively, and 3 months postoperatively, but the combined group showed better maintenance of FH at 6 months postoperatively (p = 0.049) and last follow-up (p = 0.019). The total CS (tCS) of the combined group was lower than that of the stand-alone group during the whole follow-up period (all p ≤ 0.001). Multiple linear regression suggested that lower BMD was the risk factor for main CS, and PSRF could significantly reduce the BMD threshold for severe CS (-4.77 vs -1.38). CONCLUSIONS: OLIF combined with PSRF can effectively avoid foraminal height loss and prevent severe CS, which may be more suitable for patients with osteoporosis or osteopenia and improve clinical outcomes.

Phylogenetic analysis of 56-kDa type-specific antigen gene of Orientia tsutsugamushi isolates in Taiwan.

Scrub typhus is a rickettsial disease transmitted to humans through the bite of chigger mites infected with Orientia tsutsugamushi, and is an endemic disease in Taiwan. To elucidate the molecular epidemiology of O. tsutsugamushi, the complete open reading frame of the 56-kDa type-specific antigen gene sequence of strains isolated from scrub typhus patients were determined and analyzed. A total of 116 isolates of O. tsutsugamushi were successfully isolated from patients infected in diverse geographic origins including Taiwan and three offshore islets, Kinmen, Matsu, and Penghu between May 2006 and December 2007. Sequence analysis revealed that 22 distinct sequence types could be identified that were broadly distributed in different clusters of the phylogenetic tree. Most of the isolates belong to Karp, Kawasaki, and Kuroki genotypes and are closely related to strains from Thailand, Japan, and Korea, whereas unique isolates different from other countries were also found in Taiwan. Distinct seasonal distributions were found in different sequence types. Some sequence types caused disease in the cold season, whereas others caused disease in the warm season.

Nanoscale roughness contact in a slider-disk interface.

The nanoscale roughness contact between molecularly smooth surfaces of a slider-disk interface in a hard disk drive is analyzed, and the lubricant behavior at very high shear rate is presented. A new contact model is developed to study the nanoscale roughness contact behavior by classifying various forms of contact into slider-lubricant contact, slider-disk elastic contact and plastic contact. The contact pressure and the contact probabilities of the three types of contact are investigated. The new contact model is employed to explain and provide insight to an interesting experimental result found in a thermal protrusion slider. The protrusion budget for head surfing in the lubricant, which is the ideal state for contact recording, is also discussed.