Role of a non-ionic surfactant in direct electron transfer-type bioelectrocatalysis by fructose dehydrogenase

A heterotrimeric membrane-bound fructose dehydrogenase (FDH) from Gluconobacter japonicus NBRC3260 contains FAD in subunit I and three heme C moieties in subunit II as the redox centers, and is one of the direct electron transfer (DET)-type redox enzymes. FDH-catalyzed current density of fructose oxidation at hydrophilic mercaptoethanol (MEtOH)-modified Au electrode is much larger than that at hydrophobic mercaptoethane (MEtn)-modified Au electrode. Addition of a non-ionic surfactant Triton® X-100 (1%) completely quenches the catalytic current at the MEtn-modified Au electrode, while only small competitive effect is observed at the MEtOH-modified Au electrode. Quartz crystal microbalance measurements support the adsorption of FDH and Triton® X-100 on both of the modified electrodes. We propose a model to explain the phenomenon as follows. The surfactant forms a monolayer on the hydrophobic MEtn-modified electrode with strong hydrophobic interaction, and FDH adsorbs on the surface of the surfactant monolayer. The monolayer inhibits the electron transfer from FDH to the electrode. On the other hand, the surfactant forms a bilayer on the hydrophilic MEtOH-modified electrode. The interaction between the surfactant bilayer and the hydrophilic electrode is relatively weak so that FDH replaces the surfactant and is embedded in the bilayer to communicate electrochemically with the hydrophilic electrode

Antibacterial iodine-supported titanium implants

金沢大学医薬保健研究域医学系Deep infection remains a serious complication in orthopedic implant surgery. In order to reduce the incidence of implant-associated infections, several biomaterial surface treatments have been proposed. This study focused on evaluating the antibacterial activity of iodine-supported titanium (Ti-I 2) and its impact on post-implant infection, as well as determining the potential suitability of Ti-I2 as a biomaterial. External fixation pins were used in this experiment as trial implants because of the ease of making the septic models. The antibacterial activity of the metal was measured using a modification of the Japanese Industrial Standards method. Activity was evaluated by exposing the implants to Staphylococcus aureus or Escherichia coli and comparing reaction of pathogens to Ti-I2 vs. stainless steel and titanium controls. Ti-I2 clearly inhibited bacterial colonization more than the control metals. In addition, cytocompatibility was assessed by counting the number of colonies that formed on the metals. The three metals showed the same amount of fibroblast colony formation. Japanese white rabbits were used as an in vivo model. Three pins were inserted into both femora of six rabbits for histological analysis. Pin sites were inspected and graded for infection and inflammation. Fewer signs of infection and inflammatory changes were observed in conjunction with the Ti-I2 pins. Furthermore, osteoconductivity of the implant was evaluated with osteoid formation surface of the pin. Consecutive bone formation was observed around the Ti-I2 and titanium pins, while little osteoid formation was found around the stainless steel pins. These findings suggest that Ti-I2 has antimicrobial activity and exhibits cytocompatibility. Therefore, Ti-I2 substantially reduces the incidence of implant infection and shows particular promise as a biomaterial. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Histological examination of frozen autograft treated by liquid nitrogen removed after implantation

金沢大学医薬保健研究域医学系Background: Several oncological sterilization methods involving autoclaving, irradiation, or pasteurization have been developed for limb reconstruction of large bone defects following tumor excision. Studies involving histological examinations of these autografts have all found that osteogenesis occurs slowly. We have used frozen autografts treated by liquid nitrogen for limb reconstruction and have achieved excellent results for bone union. To determine if frozen autografts exhibit early bone remodeling, we investigated the repair processes of the frozen bones. Methods: We analyzed frozen autografts treated by liquid nitrogen, retrieved at a mean of 19.1 months (2-75 months) after implantation because of complications or local tumor recurrence. The specimens were obtained from six patients with a mean age of 36.2 years (8-68 years). The six grafts comprised three osteoarticular grafts, two intercalary grafts, and one joint graft. We histologically reviewed the autograft-containing sections for tumor cell necrosis, evidence of cortical repair, the cortical junction, and joint cartilage. Results: Tumor cells were completely eradicated from the frozen bone in all cases. In a specimen retrieved 5 months after implantation, a small area of the bone showed active osteocytes and osteoblasts. In three cases retrieved more than 1 year after implantation, osteocytes and osteoblasts were observed in broad portions of the frozen bones, indicating the onset of osteogenesis in the frozen bone at an early stage. The cortical host-graft junction showed incorporation along with continuity of bone trabeculae. In addition, we were able to fi nd normal chondrocytes on the articular surface. Conclusions: The frozen bone specimens in this study thus showed evidence of newly formed bone and earlier osteogenesis than has been previously reported. Our results suggest that frozen autografts may be considered one of the most useful recycled materials for biological reconstruction. © 2009 The Japanese Orthopaedic Association

Correction of a Severe Poliomyelitic Equinocavovarus Foot Using an Adjustable External Fixation Frame

One-stage surgical correction of severe equinocavovarus deformity can result in complications ranging from skin necrosis to tibial nerve palsy. Fewer complications have been reported when severe deformities were treated by gradual correction using external frames such as the Ilizarov external fixator or the Taylor Spatial FrameTM. We describe a case of a 64-year-old female patient with severe poliomyelitic equinocavovarus whose deformity required her to ambulate using the dorsum of her right foot as a weightbearing surface. We treated the deformity with gradual correction using a Taylor Spatial FrameTM, followed by ankle arthrodesis. At the most recent postoperative evaluation, 20 months after the initial surgery, the patient was pain free and ambulating on the sole of her right foot. © 2014 American College of Foot and Ankle Surgeons

Caffeine-potentiated chemotherapy for clear cell sarcoma: a report of five cases

Background: Clear cell sarcoma is a rare malignant tumor of soft tissue which is most commonly encountered in the extremities, especially in the foot and ankle. This tumor is slow-growing and looks like a benign tumor; it is therefore often treated inadequately and its high rate of recurrence and metastases results in a poor prognosis. Caffeine has been used as a chemotherapy potentiator that inhibits DNA damage repair and enhances the cytocidal effects of anti-cancer drugs. This study reports the effect of caffeine-potentiated chemotherapy for clear cell sarcoma in five patients. Methods: Caffeine-potentiated chemotherapy was administered to five patients with clear cell sarcoma. Three to five courses of intra-arterial chemotherapy using cisplatin, doxorubicin and caffeine were administered preoperatively, at 3-week intervals. Conservatively, wide margin surgery was performed following the preoperative chemotherapy. Intravenous cisplatin and doxorubicin with caffeine were administered three to six times to the patients who responded to the preoperative chemotherapy. This study evaluated the response to chemotherapy, recurrence, metastasis and the overall prognosis in these five patients. Results: Four of the eligible patients responded to preoperative chemotherapy. Local recurrence occurred in only one of the five patients. Distant metastasis newly developed in one patient. All five patients survive. Conclusion: Caffeine-potentiated chemotherapy can be effective treatment for clear cell sarcoma not only as initial therapy, but also as salvage therapy. © 2011 Japan Society of Clinical Oncology

Prevention of pin tract infection with titanium-copper alloys

金沢大学医薬保健研究域医学系The most frequent complication in external fixation is pin tract infection. To reduce the incidence of implant-associated infection, many published reports have looked at preventing bacterial adhesion by treating the pin surface. This study aimed to evaluate the antibacterial activity of a Titanium-Copper (Ti-Cu) alloy on implant infection, and to determine the potential use of the Ti-Cu alloy as a biomaterial. Two forms of Ti-Cu alloys were synthesized: one with 1% Cu and the other with 5% Cu. For analyzing infectious behavior, the implants were exposed to Staphylococcus aureus and Escherichia coli. The reaction of pathogens to the Ti-Cu alloys was compared with their reaction to stainless steel and pure titanium as controls. Both Ti-Cu alloys evidently inhibited colonization by both bacteria. Conversely, cytocompatibility studies were performed using fibroblasts and colony formation on the metals was assessed by counting the number of colonies. Ti-1% Cu alloy showed no difference in the number of colonies compared with the control. External fixator pins made of Ti-Cu alloys were evaluated in a rabbit model. The tissue-implant interactions were analyzed for the presence of infection, inflammatory changes and osteoid-formation. Ti-1% Cu alloy significantly inhibited inflammation and infection, and had excellent osteoid-formation. Copper blood levels were measured before surgery and at 14 days postoperatively. Preoperative and postoperative blood copper values were not statistically different. Overall, it was concluded that Ti-Cu alloys have antimicrobial activity and substantially reduce the incidence of pin tract infection. Ti-1% Cu alloy shows particular promise as a biomaterial. © 2009 Wiley Periodicals, Inc

High-grade undifferentiated pleomorphic sarcoma of pelvis treated with curettage and bone graft after complete remission following caffeine-potentiated chemotherapy

金沢大学医薬保健研究域医学

Innovative antimicrobial coating of titanium implants with iodine

Background: Postoperative infection associated with implants remains a serious complication in orthopedic surgery. Several biomaterial surface treatments have been proposed as a means of reducing the incidence of implantassociated infections. In this study, a clinical trial was performed using an iodine-supported titanium that suppresses the microbial activities. Methods: A total of 222 patients with postoperative infection or compromised status were treated using iodinesupported titanium implants. The mean age of the patients was 49.4 years (range 5-85 years). One hundred twentyseven patients were male and 95 were female. In 158 patients, iodine-supported implants were used to prevent infection, such as compromised hosts and conditions, and in 64 patients to treat active infection. White blood cell (WBCs) and C-reactive protein (CRP) levels were measured pre- and postoperatively in all patients. To confirm whether iodine from the implant affected physiological functions, thyroid hormone levels in the blood were examined. Both examinations were conducted sequentially for a year. Radiological evaluations were performed regularly after the operation. The chronological changes of the iodine amount were evaluated using half pins removed after completion of external fixation. Results: The mean follow-up period was 18.4 months (range 3-44 months). Acute infection developed in three tumor cases among the 158 patients on preventive therapy. All three recovered without removal of the implants. Infection was cured in all 64 patients with infection. Median WBC levels were in the normal range, and median CRP levels returned to <0.5 within 4 weeks after surgery. Abnormalities of thyroid gland function were not detected. None of the patients experienced loosening of the implants. There were two patients with mechanical implant failure, which was treated by re-implantation. Excellent bone ingrowth and ongrowth were found around all hip and tumor prostheses. One year later, the amount of iodine on external fixation pins remained about 20-30 %. Conclusions: Iodine-supported titanium implants can be very effective for preventing and treating infections after orthopedic surgery. Cytotoxicity and adverse effects were not detected

Over 10-year follow-up of functional outcome in patients with bone tumors reconstructed using distraction osteogenesis

Background: The aim of this study was to investigate the long-term functional capabilities of patients who underwent bone distraction for the treatment of bone defects caused by bone tumor excision. Methods: Bone distraction was indicated for patients with stage IIB malignant bone tumors when chemotherapy was judged to be effective and an epiphysis could be preserved or for patients with low-grade or aggressive benign bone tumors. Twenty-two patients who underwent reconstruction with bone distraction and were followed up for at least 10 years were retrospectively investigated. Patients included 8 males and 14 females, with a mean age of 25.3 years. Tumor types included seven osteosarcomas, two osteofibrous dysplasias, one Ewing\u27s sarcoma, five low-grade osteosarcomas, two adamantinomas, and five giant cell tumors. Chemotherapy was performed during bone distraction in 8 cases. Bone transport was used in 17 cases, while shortening distraction was used in 5 cases. Results: The mean distraction length was 8.1 cm, and the mean external fixation period was 301 days. The average Musculoskeletal Tumor Society score (used to measure functional outcome) was 91.5 % at mean follow-up of 202 months. Fourteen patients were able to play sports without any difficulty. Conclusions: Epiphyseal preservation and reconstruction by bone distraction require both time and effort, but can provide excellent long-term outcomes, resulting in a stable reconstruction that functionally restores the natural limb. © 2012 The Japanese Orthopaedic Association

Caffeine activates tumor suppressor PTEN in sarcoma cells

金沢大学医薬保健研究域医学系The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a negative regulator of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. Akt activation exerts a strong anti-apoptotic effect and inhibits key pro-apoptotic proteins. We investigated the effect of caffeine in the prevention of tumor cell proliferation and induction of cell death. We found that caffeine induced increased intracellular cAMP levels, PTEN activation and Akt inactivation, which together prevented proliferation of human osteosarcoma cells (MG63) and fibrosarcoma cells (HT1080). PTEN knockdown by siRNA reduced the effects of caffeine on Akt inactivation in osteosarcoma cells. These results indicate that the tumor suppressor PTEN signaling pathway contributes to the growth-inhibitory effect of caffeine on sarcoma cells. Our data suggest that caffeine and other drugs that act on this pathway could have promising therapeutic effects in the treatment of sarcoma patients