Activation of the blood coagulation system is initiated by the binding of factor VIIa to tissue factor, which is de-encrypted on the injured endothelial cells and many other extravascular cells. A most importantcoagulation protease, thrombin, is a multifunctional protein that has, besides its function in hemostasis and thrombosis, many cellular effects that link the coagulation system with the inflammatory response, such as wound healing, atherosclerosis, angiogenesis, tumor cell growth and metastasis. Recent studies elucidated the receptor proteins for thrombin-mediated cell activation. The receptor was named as protease-activated receptor-1 (PAR-1). The subsequent studies led to the identification of the other PARs : PAR-2, PAR-3 and PAR-4. PAR-1 is activated not only by thrombin butalso by factor Xa, the tissue factor-factor VIIa complex and activated protein C in concert with endothelial protein C receptor. PAR-2 is activated by factor Xa, the tissue factor-factor VIIa complex, or the tissue factor-factor VIIa-factor Xa com-plex. PAR-3 and PAR-4 can also be activated by thrombin. In the PAR activation by the factor VIIa-tissue factor complex, the intracellular domain of the tissue factor itself may play important roles in the expression of specific cellular response in several physiological processes and in the pathogenesis of several diseases.

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The incidence of invasive fungal infections has increased in recent years among children with hematological malignancies. The extensive use of antifungal prophylaxis has resulted in limited success. Candida spp. other than C. albicans are being isolated more frequently, and incidences of aspergillosis, as well as infections due to previously uncommon organisms, are also on the rise. Empirical antifungal therapy has been standard treatment for persistent or relapsing antibiotic resistant fever, but early preemptive therapy based on serological tests and image diagnosis may offer more effective antifungal control. Amphotericin B remains the antifungal agent with the broadest spectrum of action available and thus constitutes the standard treatment for patients with proven or suspected fungal infections despite its potential for nephrotoxity. Several new antifungals have become available, including lipid formations of amphotericic B, which may allow it to be administered with reduced toxicity. However, there is still no consensus on the strategy of antifungal treatment in children with hematological malignancies, because of the paucity of pediatric data. This article provides a brief overreview of the current status of invasive fungal infections and systemic antifungal therapy in children with hematological malignancies.

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We evaluated 22 consecutive unrelated cord blood transplants (UCBT) for hematological malignancies in children at a single institute from 1999 to 2005. Six patients had UCBT as a second hematopoietic stem cell transplantation, and three patients had relapsed after the first UCBT. Median patient age was 9.5 years (range, 8 months-20 years), and median body weight was 36 kg (range, 8-64 kg). Most patients received a myeloablative conditioning regimen consisted of total body irradiation (fourteen patients) or busulfan (seven patients). Cord bloodgraft were 0-2 HLA antigen-mismatched with the recipient and contained a median cryopreserved cell dose of 4.3×10⁷ nucleated cells per kilogram (range, 2.4-11.0×10⁷/kg). Twenty patients achieved neutrophil engraftment (median 22 days). Eight patients developed acute graft-versus-host disease (GVHD) grade III-IV. With median follow-up of 6.5 months, 9/19 patients (47.4%) are alive, and eight patients died of non-relapse causes. Notably, late neutrophil engraftment (more than 22 days) was associated with worse survival rates. Relapse was the major event for patients with late engraftment. Therefore, it is important to establish a suitable conditioning regimen to introduce rapid engraftment and GVHD prophylaxis for achieving high survival rates after UCBT in children.

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A 6-year-old girl, who was diagnosed as acute myeloid leukemia (AML-M2) with t (6;9) (p23;q24) and with expression of the DAK-CAN fusion protein, treated on the CCLSG AML9805 protocol. A complete remission (CR) was achieved after induction and salvage chemotherapy. She underwent allogenic bone marrow transplantation (BMT) from an unrelated donor. The pre-conditioning regimen included busulfan and melphalan. The clinical course was uneventful, and hematological recovery occurred rapidly. She was in CR with negative PCR for DEK-CAN and survived for five years. It may be suggested that achieving DEK-CAN negativity after BMT in the first CR leads to a good prognosis for t (6;9) -AML.

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Aspergillus has become an airborne fungal pathogen and causes invasive pulmonary aspergillosis to immunocompromised patients. Since outbreaks of this pathogen at hospital have been associated with construction of the hospital, immunocompromised patients should be protected from this infection during construction. At our hospital, where many immunocompromised patients are admitted, construction work was undertaken in June 2006. We established a multidisciplinary team that includes infection control staff, hematologists, and supervisers ofthe ward, and employed proactive measures. After discussing infection control measures relevant to construction of our ward, our team recommended constructing of barriers to prevent dust from flying in all directions. To measure floating fungal pathogens, we collected dust in the air. One day after completion of the construction, Aspergillus was detected no more in the air sample. Furthermore, no outbreak of aspergillosis occurred. Our method for prevention of aspergillosis during ward construction is convenient and effective.

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