Structural and biochemical analysis of penicillin-binding protein 2 from Campylobacter jejuni.

Penicillin-binding protein 2 (PBP2) plays a key role in the formation of peptidoglycans in bacterial cell walls by crosslinking glycan chains through transpeptidase activity. PBP2 is also found in Campylobacter jejuni, a pathogenic bacterium that causes food-borne enteritis in humans. To elucidate the essential structural features of C. jejuni PBP2 (cjPBP2) that mediate its biological function, we determined the crystal structure of cjPBP2 and assessed its protein stability under various conditions. cjPBP2 adopts an elongated two-domain structure, consisting of a transpeptidase domain and a pedestal domain, and contains typical active site residues necessary for transpeptidase activity, as observed in other PBP2 proteins. Moreover, cjPBP2 responds to ß-lactam antibiotics, including ampicillin, cefaclor, and cefmetazole, suggesting that ß-lactam antibiotics inactivate cjPBP2. In contrast to typical PBP2 proteins, cjPBP2 is a rare example of a Zn2+-binding PBP2 protein, as the terminal structure of its transpeptidase domain accommodates a Zn2+ ion via three cysteine residues and one histidine residue. Zn2+ binding helps improve the protein stability of cjPBP2, providing opportunities to develop new C. jejuni-specific antibacterial drugs that counteract the Zn2+-binding ability of cjPBP2.

Enhanced tendon restoration effects of anti-inflammatory, lactoferrin-immobilized, heparin-polymeric nanoparticles in an Achilles tendinitis rat model.

Gradual wear and tear can cause a local inflammatory response in tendons. The trauma and inflammatory reaction eventually impair the biomechanical properties of the tendon. In this study, we prepared lactoferrin-immobilized, heparin-anchored, poly(lactic-co-glycolic acid) nanoparticles (LF/Hep-PLGA NPs) and evaluated their in vitro anti-inflammatory effects on interleukin-1ß (IL-1ß)-treated tenocytes and in vivo tendon healing effects in a rat model of Achilles tendinitis. Long-term LF-deliverable NPs (LF/Hep-PLGA NPs) remarkably decreased mRNA levels of pro-inflammatory factors [cyclooxygenase-2 (COX-2), IL-1ß, matrix metalloproteinase-3 (MMP-3), MMP-13, IL-6, and tumor necrosis factor-α (TNF-α)] and increased mRNA levels of anti-inflammatory cytokines (IL-4 and IL-10) in both IL-1ß-treated tenocytes and the Achilles tendons of a collagenase-induced Achilles tendinitis rat model. Interestingly, anti-inflammatory LF/Hep-PLGA NPs greatly enhanced collagen content, mRNA levels of tenogenic markers [collagen type I (COL1A1), decorin (DCN), tenascin-C (TNC)], and biomechanical properties such as tendon stiffness and tensile strength. These results suggest that anti-inflammatory LF/Hep-PLGA NPs are effective at restoring tendons in Achilles tendinitis.

High-Performance Photocatalytic Cementitious Materials Containing Synthetic Fibers and Shrinkage-Reducing Admixture.

This study aims to examine the mechanical, shrinkage and chemical properties of photocatalytic cementitious materials containing synthetic fibers and a shrinkage-reducing admixture (SRA). Two types of titanium dioxide (TiO2) powders and white Portland cement were considered along with ordinary Portland cement (OPC) as a control. Two types of synthetic fibers, i.e., glass and polyethylene (PE), and an SRA with contents varying from 0% to 3% were also considered. Using the TiO2 powders and the white Portland cement was effective in reducing the nitrogen oxides (NOx) concentration in cement composites. The use of PE fibers was more effective than glass fibers in terms of the mechanical properties, i.e., the compressive strength and tensile performance. With the addition of TiO2 powders and SRA or the replacement of OPC with white cement, the mechanical properties of the cement mortar generally deteriorated. The total shrinkage of the mortar could be reduced by incorporating the fibers at volume fractions greater than 1%, and the glass fiber was more effective than the PE fiber in this regard. The TiO2 powders had no significant impact on the shrinkage reduction of the cement mortar, whereas the SRA and the white Portland cement effectively reduced shrinkage. The addition of 3% SRA decreased the total shrinkage by 43%, while the replacement of the OPC with white cement resulted in a 20% reduction in the shrinkage.

Modified Broström Procedure Using Distal Fibular Periosteal Flap Augmentation vs Anatomic Reconstruction Using a Free Tendon Allograft in Patients Who Are Not Candidates for Standard Repair.

BACKGROUND: The modified Broström procedure (MBP) is widely accepted as the primary operative treatment for chronic lateral ankle instability (CLAI). However, the MBP does not produce good clinical results in all patients, and anatomic reconstruction using a free tendon graft may be considered in those patients. The purpose of this study was to evaluate the efficacy of the MBP using distal fibular periosteal flap augmentation for CLAI in patients who were not candidates for standard repair. METHODS: Thirty-eight patients (39 ankles) who underwent surgery for CLAI were retrospectively analyzed. The patients were divided into 2 groups: an anatomic lateral ligament reconstruction group (reconstruction group) consisting of 17 ankles and an MBP group using distal fibular periosteal flap augmentation (augmentation group) consisting of 22 ankles. Preoperative and postoperative clinical evaluations were performed using the visual analog scale (VAS), American Orthopaedic Foot & Ankle Society (AOFAS), and Karlsson-Peterson (Karlsson) scores. RESULTS: The mean VAS, AOFAS, and Karlsson scores significantly improved from 4.0 to 1.8, 54.7 to 92.9, and 46.4 to 92.7, respectively, in the reconstruction group ( P < .001, P < .001, P < .001), and from 4.1 to 1.5, 60.1 to 94.9, and 52.6 to 94.1, respectively, in the augmentation group ( P < .001, P < .001, P < .001). There were no significant differences in the mean postoperative AOFAS and Karlsson scores between the groups ( P = .214, P = .299). CONCLUSION: The MBP using distal fibular periosteal flap augmentation was also an effective option for CLAI in cases of generalized ligament laxity, severe attenuation of the soft tissue, previous failed surgery, high demand activity, and obesity. LEVEL OF EVIDENCE: Level III, comparative series.

Revision Surgery for Recurrent Pain after Excision of the Accessory Navicular and Relocation of the Tibialis Posterior Tendon.

BACKGROUND: The results of operative treatments for symptomatic accessory navicular are debatable. In some cases, recurrent pain may develop after the Kidner procedure. The purpose of this study is to review the reasons for recurrent pain after the Kidner procedure and to suggest possible options for revision surgery. METHODS: We reviewed the clinical and radiological outcomes in 9 patients who underwent revision surgery for recurrent pain after the Kidner procedure. During the revision surgery, the tibialis posterior tendon was reattached to the navicular either by advancing the tendon in 4 patients or by lengthening the tendon in another 4 patients. In the other 1 patient, the flexor digitorum longus tendon was transferred. Surgeries for the accompanying deformities were performed simultaneously in all patients. The results were evaluated using the American Orthopaedic Foot and Ankle Society ankle-hindfoot score and a visual analog scale. The mean follow-up was 2.3 years (range, 1 to 5 years). RESULTS: The mean American Orthopedic Foot and Ankle Society ankle-hindfoot score improved from 71.25 to 81.50 in the advancement group, and 71.75 to 90.00 in the lengthening group. The mean visual analog scale improved from 7.75 to 4.25 in the advancement group and from 7.50 to 1.75 in the lengthening group. CONCLUSIONS: Recurrent pain after the Kidner procedure was associated with pes planovalgus or hindfoot valgus deformity. In revision surgery, correction of the associated deformities and reattachment of the tibialis posterior tendon after lengthening may need to be considered.

Talofibular Bony Impingement in the Ankle.

BACKGROUND: Talofibular bony impingement has not previously been reported, since it is difficult to detect on plain radiograph, similar to the spur on the anterior border of the medial malleolus and anterior portion of the medial talar facet. We hypothesized that talofibular bony impingement can cause limited dorsiflexion of the ankle. The aim of this study was to evaluate talofibular bony impingement as a distinct form of impingement that limits dorsiflexion of the ankle. METHODS: This study included 20 consecutive patients (21 ankles) with talofibular impingement and 19 consecutive patients (19 ankles) with lateral ankle instability without talofibular impingement. Presence or absence of talofibular impingement was confirmed under direct intraoperative visualization. Dorsiflexion before and after excision of the impinging spurs was measured. Findings on plain radiographs and computed tomography were compared between the groups. Pre- and postoperative clinical assessments were done with Foot Function Index, visual analog scale for pain, and American Orthopaedic Foot & Ankle Society ankle-hindfoot score at a mean follow-up of 1.4 years. RESULTS: After removal of the bony impingement, the range of dorsiflexion increased by a mean 7.9 degrees (range, 2.5 to 11.0 degrees) in the impingement group. The mean distance between the fibula and lateral process of the talus on weight- bearing anteroposterior radiograph of the ankle was 1.2 mm (range, 0 to 4.5) in the impingement group and 3.2 mm (range, 1 to 4.5) in the control group. On axial computed tomography image, bony protrusion of the lateral process of the talus was frequently present in the impingement group, and the mean amount of protrusion was more than that of the control group. Clinical findings improved overall. CONCLUSIONS: Talofibular impingement was a cause of limited dorsiflexion, and the diagnosis was confirmed intraoperatively. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

The effectiveness of minimally invasive total knee arthroplasty to preserve quadriceps strength: a randomized controlled trial.

We performed a single-center, randomized, double-blind study to compare muscle strength in patients who had undergone primary total knee arthroplasty (TKA), performed using either a minimally invasive or a conventional surgical technique. We evaluated 30 knees in healthy age-matched subjects, 22 knees after conventional TKA (conventional group), and 23 knees after minimally invasive surgery TKA (MIS group). The Hospital for Special Surgery (HSS) score, Oxford knee score (OKS), and isokinetic (60º/s) muscle strength were evaluated the day before surgery and 3, 6, and 12 months after surgery. HSS and OKS improved significantly over time during follow-up (p<0.001), but there was no significant difference between the groups (p>0.05). The extensor peak torque (EPT) and flexor peak torque (FPT) improved significantly over time (p<0.001) and EPT was greater in the MIS group than in the conventional group during the follow-up period (p<0.05). There was no difference in FPT and the hamstring-to-quadriceps ratio between the groups. Although MIS patients had a significant deficit in extensor strength following TKA, compared with healthy controls, this approach offers a significant improvement in extensor muscle strength over conventional surgery. These results suggest that the MIS approach results in better outcomes with regard to maintaining extensor strength than the conventional surgical approach.