• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.8 no.2
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• pp.213-221
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• 2005

Purpose: Hemophagocytic syndrome (HPS) is characterized by persistent high fever, hepatosplenomegaly, cytopenias, hypertriglyceridemia, and/or hypofibrinogenemia. Hepatic manifestations including overt hepatic failure and fulminant hepatitis are common in HPS. Liver transplantation (LT) should be considered in a case of fulminant hepatitis by other than HPS, but LT is contraindicated and complete cure is possible by chemotherapy in HPS. Therefore, we conducted this study to define the characteristics of HPS presenting as severe acute hepatitis. Methods: Among the total of 23 patients diagnosed as HPS by bone marrow examination between 1994 and 2005 in Asan Medical Center, 11 cases presented as severe acute hepatitis were enrolled in this study. We analyzed the clinical features, laboratory findings and outcome retrospectively. Results: Seven (64%) of the 11 children with HPS and hepatitis were referred to pediatric gastroenterologist at first. The mean age of onset was 50 months. There was no case with family history of primary HPS. Epstein-Barr virus was positive in 4, and herpes Simplex virus was positive simultaneously in 1 case. As the presenting symptoms and signs, fever was present in 10, hepatosplenomagaly was noted in all and jaundice in 10. Anemia was observed in 10, thrombocytopenia in 10, leukopenia in 8, hypertriglyceridemia in 9, hypofibrinogenemia in 8 and hyperferritinemia in 7 cases, respectively. Nine children received chemotherapy including etopside. The overall mortality rate was 72% (8/11). Conclusion: HPS, which needs chemotherapy, should be considered as a cause of severe acute hepatitis especially when accompanied with prolonged high fever and cytopenias.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.162-174
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• 1997

Background : Metabolic cooperation via gap junctional intercellular communication (GJIC) is an important mechanism of the bystander effect in gene therapy using the Herpes Simplex Virus thymidine kinase/ganciclovir (HSVtk) "prodrug" system. Since retinoids have been reported to increase GJIC by induction of connexin 43 expression, we hyporthesized that treatment of tumor cells with retinoic acid could augment the bystander effect of the HSVtk/GCV system and result in improved tumor cell killing by enhancing GJIC. Methods : We transferred HSVtk gene to SKHep-J cell line that does not express connexin43, and also transferred the gene to human and murine mesothelioma cell lines that express connexin43. We verified that retinoic acid enhanced GJIC utilizing a functional double-dye transfer study and evaluated the effects of retinoic acid on the growth rate of tumor cells. We then tested the effects of retinoic acid on bystander-mediated cell killing. Results : Addition of all-trans retinoic acid (RA) increased GJIC in cell lines expressing connexin 43 and was asspciated with more efficient in vitro bystander killing in cells transduced with HSVtk via adenoviral and retroviral vectors. In contrast, there was no increase in the efficiency of the bystander effect after exposure to RA in a cell line which had no delectable connexin 43. Conclusion : These results provide evidence that retinoids can augment the efficiency of cell killing with the HSVtk/GCV system by enhancing bystander effect and may thus be a promising new approach to improve responses in gene therapy utilizing the HSVtk system to treat tumors.

• Tuberculosis and Respiratory Diseases
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• v.46 no.2
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• pp.229-240
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• 1999

Background: The impact of the immune response on cancer gene therapy using viral vectors to deliver a "suicide gene" is currently unclear. A vigrous immune response targeted at viral proteins or transgene may enhance the efficacy of tumor destruction and even augment responses to tumor antigens. These responses may involve the release of cytokines and stimulation of tumor specific cytotoxic T-lymphocytes that enhance therapeutic efficacy. On the other hand, a vigorous rapid cellular immune response may destroy cells expressing the therapeutic gene and attenuate the response to therapy. Furthermore, development of neutralizing antibody responses may prevent readministration of virus, a potentially significant limitation. Evaluating the significance of these limitations in animal models and developing solutions are therefore of obvious importance. Methods: After retroviral transduction of mouse mesothelioma cell line(AB12) with Herpes Simplex Virus thymidine kinase (HSVtk) gene in vitro, subcutaneous flank tumors were established. To study the effect of intact immune system on efficacy of tumor erradication, the ability of the HSVtk/ganciclovir system to inhibit tumor growth was compared among normal Balb/c mice, immunodeficient Balb/c-nude and SCID mice, and Balb/c mice immunosuppressed with cyclosporin. Results: Ganciclovir treatment resulted in greater inhibition of tumor growth in Balb/c mice compared with immunodeficient Balb/c-nude mice and SCID mice(in immunodeficient mice, there were no growth inhibition by ganciclovir treatment). Ganciclovir treatment resulted in greater inhibition of tumor growth in noncyclosporin (CSA) treated Balb/c mice compared with CSA treated Balb/c mice. On day 8, mean ganciclovir-treated tumor volume were 65% of control tumor volume in Balb/c mice versus 77% control tumor volume in CSA-treated Balb/c mice. This effect was still evident during therapy (day 11 and 13). On day 13, non-CSA treated tumor volume was 35% of control tumor volume versus 60% of control tumor volume in CSA treated Balb/c mice. Duration of expression of HSVtk was not affected by the immunosuppression with CSA. Conclusion: These results indicate that the immune responses against retrovirally transduced cells enhance the efficacy of the HSVtk/ganciclovir system. These findings have important implications for clinical trials using currently available retrovirus vectors as well as for future vector design.