Spontaneous reduction of iron(III)porphyrin to iron(II)porphyrin-CO complex in mouse circulation.

Iron(II/III)porphyrin/cyclodextrin inclusion complexes serve as hemoprotein models in vivo. Here we showed the iron(III)porphyrin complex to be spontaneously reduced to its iron(II) state in mouse circulation. The reduced complex bound endogenous CO from carboxyhemoglobin, which was followed by urinary excretion. The natural reduction system was found to be effective for synthetic heme-model compounds.

An intramedullary free vascularized fibular graft combined with pasteurized autologous bone graft in leg reconstruction for patients with osteosarcoma.

The use of pasteurized autologous bone graft has been an innovation in limb-salvage surgery; however, its principal disadvantage is fracture, infection, pseudoarthrosis, and bone resorption. We present two cases in which an intramedullary free vascularized fibular graft combined with pasteurized autologous bone graft was performed for immediate femur or tibia reconstruction following osteosarcoma resection. The rationale of this method is to combine the mechanical strength of a pasteurized bone with the biological activity of a vascularized bone. The pasteurized bone graft provides bone stock and early stability and the addition of the vascularized bone graft substantially facilitates host-pasteurized bone union. This combination procedure may be a recommended option for reconstruction of the lower leg, preserving knee joint function for patients with osteosarcoma.

Atypical Mycobacterium infections of the upper extremity.

BACKGROUND: We encountered five patients with atypical Mycobacterium infections in the upper extremity, and examined their outcomes. PATIENTS AND METHODS: Two patients were male and three were female. The average patient age was 67 (range, 63-75) years. A wide synovectomy was performed to diagnose all cases followed by a therapeutic regimen of Rifampicin, Isoniazid, and Ethambutol. RESULTS: The causative atypical organism was Mycobacterium marinum in three cases and Mycobacterium intracellulare in two cases. In one patient, inflammation recurred or did not disappear, and, therefore, three debridements were necessary. The average duration of antimicrobial therapy was 12 (range, 5-24) months. The average follow-up period was 26 (range, 5-66) months, and resolution had been achieved in all cases at the time of follow-up evaluation. CONCLUSION: Surgical debridement and appropriate mycobacterial culture or PCR method are critical to enable diagnosis and appropriate management.

Use of vascularized pedicle iliac bone graft combined with transtrochanteric rotational osteotomy in the treatment of avascular necrosis of the femoral head.

INTRODUCTION: A vascularized pedicle iliac bone graft combined with transtrochanteric anterior rotational osteotomy was performed in patients with extensive necrosis in whom the necrotic area occupied more than two-thirds of the weight-bearing zone of the femoral head. The purpose of this procedure is to supply vascularity and mechanical strength to the avascular femoral head. MATERIALS AND METHODS: Seventeen hips in 14 patients (8 male, 6 female) whose average age at surgery was 37.9 (range 21-51) years underwent this procedure between June 1992 and December 2002. These hips (stage 2 in 3 hips, stage 3A in 13 hips, and stage 3B in 1 hip) were examined for changes according to the Japanese Orthopedic Association (JOA ) score and the presence or absence of progression of the clinical stage at least 1 year after surgery. RESULTS: The mean JOA score improved from 67.8 points preoperatively to 78.1 points by 18-133 (mean 50.7) months postoperatively. There was no disease progression to a more advanced stage in 12 of 17 hips (71%) postoperatively. CONCLUSION: A vascularized pedicle iliac bone graft combined with transtrochanteric anterior rotational osteotomy to treat avascular necrosis of the femoral head is considered promising for joint preservation.

Mechanism of apoptotic resistance of human osteosarcoma cell line, HS-Os-1, against irradiation.

In our previous study, we examined reactive oxygen species (ROS) formation in T lymphocytes following 5 Gy of irradiation. Using a CCD camera system, we monitored fluorescence in T lymphocytes loaded with the succinimidyl ester of Dichlorodihydrofluorescein diacetate (H2DCFDA), which is non-fluorescent until oxidized by ROS. We found that ROS formation occurred immediately after irradiation, continued for several hours, and resulted in oxidative DNA damage. Therefore, the origin of the hyper-radiosensitivity of T lymphocytes seemed to be the high production of ROS in the mitochondrial DNA following irradiation. In this study, we examined radiation-induced ROS formation, oxidative DNA damage, early apoptotic changes, and mitochondrial membrane dysfunction in the human osteosarcoma cell line HS-Os-1, which was established from an osteoblastic tumor that arose in the left humerus of an 11-year-old girl and was already morphologically characterized in vitro and in vivo. We found that ROS formation and oxidative DNA damage were actually scarcely seen after irradiation of up to 30 Gy in these cells; that mitochondrial membrane potential was preserved; and that apoptotic changes were not demonstrated despite the relatively high-dose irradiation of 30 Gy. Therefore, the origin of the close similarity of radiosensitivity between adult articular chondrocytes and the human osteosarcoma cell line HS-Os-1, is considered to involve the low degree of ROS formation following irradiation; the similarity possibly results from the strong scavenging ability of these two kinds of cells for free radicals including hydroxyl radicals.

Mechanism of hydrogen peroxide-induced apoptosis of the human osteosarcoma cell line HS-Os-1.

In our previous study, we examined radiation-induced ROS formation, oxidative DNA damage, early apoptotic changes, and mitochondrial membrane dysfunction in the human osteosarcoma cell line HS-Os-1, which was established from an osteoblastic tumor that arose in the left humerus of an 11-year-old girl and was already morphologically characterized in vitro and in vivo. We found that ROS formation and oxidative DNA damage were scarcely seen after irradiation of up to 30 Gy in these cells; that mitochondrial membrane potential was preserved; and that apoptotic changes were not demonstrated despite the relatively high-dose irradiation of 30 Gy. Based on these results, the radioresistance of the human osteosarcoma cell line HS-Os-1, was considered to arise, at least in part, from the low level of ROS formation following irradiation, which in turn may have resulted from the strong scavenging ability of the cells for free radicals, including hydroxyl radicals. Therefore, in this study, we examined the effect of exogenous hydrogen peroxide, which causes a potent oxidative stress and has been demonstrated to be a potent apoptosis-inducer in many kinds of cells. We found that addition of 1 or 10 mM hydrogen peroxide induced ROS formation, oxidative DNA damage, dysfunction of the mitochondrial membrane potential, and early apoptotic changes in the human osteosarcoma cell line HS-Os-1. We therefore concluded that intracellular ROS formation is involved in the hydrogen peroxide-induced apoptosis of HS-Os-1 cells.