Immobilization of Collagen on the Surface of a PEEK Implant with Monolayer Nanopores.

Polyetheretherketone (PEEK) is the only polymer material that can replace titanium implants in the field of orthopedics. This is because the mechanical properties of PEEK are similar to those of bone, and PEEK has natural radiolucency, chemical stability, and sterilization resistance. Despite these advantages, PEEK has a disadvantage-that it is bio-inert. Therefore, many studies have attempted to change the bio-inertness of PEEK into bioactivity. Among them, a method of forming pores by acid treatment is attracting attention. In this study, an attempt was made to form pores on the surface of PEEK implant using a mixed acid of sulfuric acid and nitric acid. As a result, it was found that the condition when the PEEK surface is in contact with the acid is very important. That is, it was possible to form single-layered nanopores on the surface by contacting PEEK with a mixed acid under ultrasound. Additionally, by immobilizing type I collagen on the porous PEEK surface through dopamine coating, it was possible to obtain collagen-immobilized porous PEEK (P-PEEK-Col) with high compatibility with osteoblasts. This P-PEEK-Col has high potential for use as a bone substitute that promotes bone formation.

Cytoplasmic HMGB1 and HMGB1-Beclin1 complex are increased in radioresistant oral squamous cell carcinoma.

Cytoplasmic high mobility group box 1 (HMGB1) is an autophagy regulator, and autophagy is important in the radioresistance of various solid cancers. We evaluated the degree of autophagy and cytoplasmic HMGB1 in radioresistant oral squamous cell carcinoma (SCC) by culturing the SCC15 and quasiliquid layer 1 (QLL1) SCC cell lines that originate from cancer of the oral tongue and a metastatic lymph node, respectively, and then delivered radiation to induce radioresistance to cells. We then compared the degree of autophagy between non-irradiated control and radioresistant cancer cells using a western blot assay. We also compared the total and cytoplasmic concentrations of HMGB1 between the non-irradiated control and radioresistant cancer cells by western blot assay, and extracellular concentrations of HMGB1 with an enzyme-linked immunosorbent assay (ELISA). Formation of an HMGB1-Beclin1 complex was evaluated by immunofluorescence and co-immunoprecipitation assays. Autophagy increased in the radioresistant SCC15 cells (compared with non-irradiated control SCC15 cells) but not in the radioresistant QLL1 cells. The total amount of HMGB1 expression within cells did not differ; however, the degree of cytoplasmic HMGB1 expression was higher in radioresistant SCC15 cells than in non-irradiated control SCC15 cells. The HMGB1-Beclin1 complex, which is a main regulator of autophagy, was also increased in radioresistant SCC15 cells compared with non-irradiated control SCC15 cells. Autophagy flux and cytoplasmic HMGB1-Beclin1 increased after the acquisition of radioresistance in oral SCC.

Clinical utility of cervical vestibular-evoked myogenic potentials in predicting residual dizziness after benign paroxysmal positional vertigo.

OBJECTIVES: In the present study, the value of cervical vestibular-evoked myogenic potential (cVEMP) as a predictive factor for residual dizziness after recovery of benign paroxysmal positional vertigo (BPPV) was evaluated. METHODS: The present study included 65 patients who had BPPV and underwent cVEMP testing. Patients were divided into two groups depending on the presence or absence of residual dizziness after recovery of BPPV. Univariate and multivariate analyses were performed to determine the factors associated with residual dizziness using age, gender, affected semicircular canal, affected side, BPPV duration, and cVEMP parameters. RESULTS: In univariate analysis, cVEMP-modified interaural amplitude difference (IAD) ratio and p13 latency showed a relatively significant association (p < 0.20) with residual dizziness. Based on multivariate analysis, increased cVEMP-modified interaural amplitude difference (IAD) ratio at the affected side (≥25%; p = 0.018, OR 6.623) remained as an associated factor. CONCLUSIONS: Increased cVEMP-modified IAD ratio at the affected side is associated with residual dizziness. BPPV patients with increased cVEMP-modified IAD ratio at the affected side are more likely to have residual dizziness after recovery of BPPV. SIGNIFICANCE: cVEMP testing could be used for the prediction of residual dizziness. An increased cVEMP-modified IAD ratio at the affected side may be used as a predictor of residual dizziness.