Spread of the community-acquired methicillin-resistant Staphylococcus aureus USA300 clone among family members in Japan.

The USA300 clone is a highly-virulent community-acquired methicillin-resistant Staphylococcus aureus, which has been predominant in the United States. In a previous study, we isolated the USA300 clone from an 11-month-old Japanese girl, who lived in Saitama (Japan), and suffered from cellulitis and sepsis, and subsequently osteomyelitis, in 2008. In this study, we searched for the source of such USA300 infection in three related families (the patient's grandfather and grandmother, having a USA300-infected daughter [F2D], and a mother [F3M] who was a sister of F2D's mother). In January, 2008, F3M and her family members visited Hawaii and were treated in a hospital for gastroenteritis (with diarrhea) with an intravenous drip for F3M. After their return to Japan in January, F3M suffered from unusually frequent (more than 10 times) skin soft-tissue infections (SSTIs) until successful chemotherapy in July in Saitama. In the same summer season, SSTI was observed in 7 of 11 family members (63.6%). This dense spread of SSTI was followed by cellulitis and sepsis (USA300-isolated case) in October and subsequent osteomyelitis in December in F2D. After successful chemotherapy for the patient (F2D), no new SSTI cases were observed among the family members, and no USA300 colonization was observed when examined in December, 2009. The data suggest the first spread of the USA300 clone in Japan with related families at the core and that such USA300 spread in the community is likely to have occurred in the summer season in Japan.

Emergence of the community-acquired methicillin-resistant Staphylococcus aureus USA300 clone in a Japanese child, demonstrating multiple divergent strains in Japan.

In 2008 we isolated methicillin-resistant Staphylococcus aureus (MRSA) from an 11-month-old Japanese girl who lived in Saitama, Japan, and suffered from cellulitis of the lower thigh and sepsis. The MRSA (strain NN47) belonged to multilocus sequence type (ST) 8 and exhibited spa363 (t024), agr1, staphylococcal cassette chromosome mec (SCCmec) type IVa, and coagulase type III. It was positive for Panton-Valentine leukocidin (PVL) and the arginine catabolic mobile element (ACME). Pulsed-field gel electrophoresis (PFGE) demonstrated that the MRSA was the USA300 clone, which is the predominant community-acquired MRSA (CA-MRSA) in the US. Strain NN47 was divergent, in terms of the spa type and patterns of PFGE and plasmids, from the USA300-0114 type strain or USA300 strain NN36, previously isolated from a visitor (Indian girl) from the US. Strain NN47 was resistant to erythromycin, in addition to beta-lactam agents (e.g., oxacillin). These data demonstrate the first emergence of the USA300 clone in Japanese children who have never been abroad and have had no contact with foreigners (and therefore, the first USA300 spread in Japan), and also emergence of multiple divergent strains of the USA300 clone in Japan. Because the USA300 clone is highly transmissible and virulent, surveillance of the USA300 clone is needed.

Characterization of the MM.1 human multiple myeloma (MM) cell lines: a model system to elucidate the characteristics, behavior, and signaling of steroid-sensitive and -resistant MM cells.

Multiple myeloma (MM) is a clonal B-lymphocyte malignancy, which is characterized by the accumulation of terminally differentiated antibody-producing cells in the bone marrow. Because current treatments offer only a median survival of 3 years, investigators continue to search for novel therapeutic strategies to combat the disease. Rational drug design is enhanced by understanding MM cell proliferation and key signaling pathways employed. In addition, a model system for preclinical evaluation of novel therapeutics is critical. Our laboratory has developed MM cell lines to study drug action and resistance, cell proliferation, and apoptosis. These cell lines are widely used in MM research. From a single MM patient, three separate cell lines were established that parallel the progression of the disease. These three cell lines, designated MM1.S, MM1.R(E), and MM1.R(L), can be distinguished on the basis of their sensitivity to steroid hormones such as glucocorticoids (GCs). Utilization of these cell lines to study the etiology of MM, effects of chemotherapeutic agents, and development of clinical resistance, will provide us with vital information for the evolution of new and more efficacious therapeutics. The aim of this review is to summarize the morphological, biochemical, and growth characteristics of these cells, and to review the results from investigations of the MM.1 signaling pathways. This information will enhance the study, treatment, and eventual eradication of MM.

Effects of sodium in hydration solution on plasma methotrexate concentrations following high-dose methotrexate in children with acute lymphoblastic leukemia.

PURPOSE: To test whether a higher sodium dose in the hydration solution may facilitate faster methotrexate (MTX) elimination as compared with a lower sodium dose following high-dose MTX (HDMTX) treatment. METHODS: Intravenous solutions with alternate doses of sodium (regimen A 70 mEq/l, regimen B 100 mEq/l) were given to 30 children with acute lymphoblastic leukemia in two courses of HDMTX in a randomized crossover fashion. The plasma MTX concentrations every 24 h from the beginning of MTX administration and the adverse events associated with HDMTX were compared between the two hydration regimens. RESULTS: The plasma MTX concentrations were similar in the two hydration regimens at 24 h (A 50.9+/-7.4 vs B 40.9+/-5.4 microM, means+/- SE, P=0.17), but was significantly lower in regimen B at 48 and 72 h (A 0.65+/-0.17 vs B 0.27+/-0.03 microM, P=0.04; and A 0.14+/-0.03 vs B 0.05+/-0.01 microM, P=0.003). The time during which MTX plasma concentrations exceeded 0.1 microM was significantly longer in regimen A than in regimen B (A 3.83+/-0.18 vs B 3.13+/-0.06 days, P=0.001). The incidences of adverse events were similar between the two regimens ( P=0.78), and severe adverse events were not seen in either regimen. CONCLUSIONS: Hydration with a higher sodium dose facilitated faster MTX elimination following HDMTX. Sodium may have a beneficial effect on MTX-induced nephrotoxicity.

A pediatric case of secondary leukemia associated with t(16;21)(q24;q22) exhibiting the chimeric AML1-MTG16 gene.

A chimeric gene, AML1-MTG16, showing high homology to AML1-MTG8, was recently identified in adult leukemic patients with the abnormal karyotype t(16;21)(q24;q22). We recently saw a child patient of 11 years of age who developed acute myelogenous leukemia with the karyotype t(16;21)(q24;q22), 11 months after autologous peripheral blood stem-cell transplantation (PBSCT) for acute promyelocytic leukemia with karyotype t(15;17)(q22;q11). The reciprocal translocation was localized by fluorescence in situ hybridization (FISH) analysis, reverse transcription polymerase chain reaction (RT-PCR), and Southern blot analysis of bone marrow blood cells and peripheral blood cells. FISH analysis identified a reciprocal translocation between chromosomes 16 and 21. RT-PCR analysis identified expression of the chimeric gene AML1-MTG16. Southern blot analysis revealed a breakpoint occurring at a 1.4 kb Eco RI fragment between exons 3 and 4 of MTG16. The breakpoint is within the same region as that of secondary leukemias, which has been reported previously. This case suggests the possibility that the region of the breakpoint of MTG16 is a characteristic of secondary leukemia.