Imipenem plus Fosfomycin as Salvage Therapy for Vertebral Osteomyelitis.

We applied combination antibiotic therapy to treat vertebral osteomyelitis and a psoas abscess caused by glycopeptide-intermediate (MIC, 2 µg/ml) and daptomycin-nonsusceptible (>2 µg/ml) methicillin-resistant Staphylococcus aureus The Etest synergy test showed the largest synergistic effects for imipenem/cilastatin and fosfomycin. Whole-gene sequencing showed amino acid changes in SA0802, SA1193 (mprF), and SA1531 (ald). Four weeks of combination treatment using imipenem/cilastatin (1.5 g per day) and fosfomycin (4.0 g per day) resulted in clinical improvement.

Nitration of specific tyrosine residues of cytochrome C is associated with caspase-cascade inactivation.

Peroxynitrite, a potent oxidative stress inducer, inhibits the mitochondrial electron transfer, induces cell death, and is considered to be involved in the pathology of various diseases. However, the intracellular mechanisms involved in the cell death process are not fully understood. Here we demonstrate that the enhanced nitration of specific tyrosine residues of cytochrome c, which are induced by continuous peroxynitrite exposure, attenuates cytochrome c-induced caspase-9 activation in vitro. Interestingly, cytochrome c nitrated with a single high dose of peroxynitrite preserved its potency, while this did not occur when cytochrome c was treated with continuous peroxynitrite exposure. Although both of these experiments resulted in cytochrome c nitration at the tyrosine residues, it was found that nitration at specific residues was enhanced only when cytochrome c was exposed to continuous peroxynitrite. This is the first report to demonstrate that cytochrome c nitration affects the apoptotic pathway by means of enhancement of nitration at specific tyrosine residues. This result implies that the nitration pattern of cytochrome c may affect the efficacy of the mitochondrial pathway in apoptotic cell death.

Induction of radical scavenging ability and suppression of lipid peroxidation in rat liver microsomes following whole-body, low-dose X-irradiation.

PURPOSE: To investigate changes in radical scavenging ability and lipid peroxidation in liver microsomal membranes and cooperative suppression of lipid peroxidation by microsomal and cytosolic radical scavengers, 24 h after whole-body, low-dose X-irradiation of rats. MATERIALS AND METHODS: Male Wistar rats were irradiated with 1-50 cGy of X-rays. Liver microsomal radical scavenging ability was determined using the trapping ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH), a stable free radical. Microsomal alpha-tocopherol (Vit.E) content was determined using an electrochemical detector. Microsomal glutathione peroxidase (GPx) activity was determined as the consuming rate of NADPH. Microsomal lipid peroxidation was determined by the thiobarbituric acid method. RESULTS: Low molecular weight radical scavenging ability of rat liver microsomes increased 24 h after whole-body, low-dose X-irradiation when alpha-tocopherol was included, showing a maximum level at 5-10 cGy. Microsomal GPx activity also increased 24 h after 5 cGy irradiation. The lipid peroxidation level in microsomes decreased, showing a maximal suppression at 5 cGy. High-dose irradiation-induced microsomal lipid peroxidation was strongly suppressed cooperatively by microsomal and cytosolic antioxidants induced by low-dose irradiation. CONCLUSION: Low doses of radiation induce increases in liver microsomal antioxidants, which in turn result in enhanced suppression of microsomal lipid peroxidation cooperatively with cytosolic antioxidants induced by low-dose irradiation.

Radiation adaptive response of glial cells.

There are various types of radiation in space including high energy particles. It is, therefore, becoming to be important to study the low dose and low dose-rate effects in space radiation biology. Radiation adaptive response (RAR) for cell growth and its mechanism were examined using cultured glial cells. The cells from hippocampus of Wistar rats were irradiated with a low dose (0.1 Gy) of X-rays and 3 h after with a high dose (2 Gy). Decrease in the rate of cell growth with 2 Gy was suppressed by the 0.1 Gy preirradiation, when cells were counted 2 days after irradiation. The inhibitors of protein kinase C (PKC) and DNA-dependent protein kinase (DNAPK) or phosphatidylinositol 3-kinase (PI3K) suppressed RAR. The treatment with the activators of PKC instead of 0.1 Gy-preirradiation also caused adaptive response to 2 Gy-irradiation. Moreover, glial cells cultured from severe combined immunodeficiency (scid) mice, which have lost DNAPK activity, and AT-2KY cells, fibroblasts of an ataxia-telangiectasia (AT) patient, showed no RAR. These results indicated that PKC, ATtM, DNAPK and/or PI3K were involved in RAR for growth of cultured glial cells. Proteomics [correction of preteomics] analysis of these cells exposed to low dose irradiation in now underway.