Search for the Majorana Nature of Neutrinos in the Inverted Mass Ordering Region with KamLAND-Zen.

The KamLAND-Zen experiment has provided stringent constraints on the neutrinoless double-beta (0νßß) decay half-life in ^{136}Xe using a xenon-loaded liquid scintillator. We report an improved search using an upgraded detector with almost double the amount of xenon and an ultralow radioactivity container, corresponding to an exposure of 970 kg yr of ^{136}Xe. These new data provide valuable insight into backgrounds, especially from cosmic muon spallation of xenon, and have required the use of novel background rejection techniques. We obtain a lower limit for the 0νßß decay half-life of T_{1/2}^{0ν}>2.3×10^{26} yr at 90% C.L., corresponding to upper limits on the effective Majorana neutrino mass of 36-156 meV using commonly adopted nuclear matrix element calculations.

Stimulation of connective tissue-type mast cell proliferation by crosslinking of cell-bound IgE.

Crosslinking of cell-bound IgE on mouse connective tissue-type mast cells (CTMC) by multivalent antigen or anti-IgE antibody induced clonal growth of CTMC in methylcellulose culture containing IL-3. Continuous presence of antigen, IgE antibody, and IL-3 in culture was required for extensive proliferation of CTMC. Optimal concentrations of antigen and anti-IgE antibody for proliferation of sensitized CTMC approximately corresponded to those for maximal histamine release from the cells, and it was observed that most dividing cells stimulated by antigen had pericellular degranulation halos in culture. Experiments of both single cell culture and serum free culture provided evidence for a direct effect of antigen stimulation on proliferation of CTMC. Neither accessory cells nor some factors in FCS were required for the clonal growth of CTMC in our culture condition. Compound 48/80, a direct stimulator of CTMC, also triggered histamine release from CTMC but failed to support their proliferation. These results suggest that stimulation of CTMC via IgE receptors not only triggers the release of chemical mediators from the cells but induces clonal growth of CTMC in the presence of IL-3. Our data indicate the possibility that antigen stimulation may play another role in the proliferation of CTMC.

Synergism of BSF-2/interleukin 6 and interleukin 3 on development of multipotential hemopoietic progenitors in serum-free culture.

We investigated the effects of B cell stimulatory factor 2/interleukin 6 (BSF-2/IL-6) on the development of murine hemopoietic progenitors using serum-containing culture and serum-free culture. In serum-containing culture, BSF-2 mainly supported multipotential blast cell colonies from spleen cells of normal and 5-fluorouracil (5-FU)-treated mice. In serum-free culture, no colony growth was seen in the presence of BSF-2. Addition of BSF-2 to the serum-free culture containing IL-3 resulted in a significant increase in the number of colonies formed from multipotential progenitors in spleen cells and bone marrow cells of 5-FU-treated mice, whereas no effects were seen on the number of single or oligolineage colonies formed by the spleen cells of normal mice. These results suggested that BSF-2 and IL-3 act synergistically on the multipotential progenitors but not on the maturer progenitors. When BSF-2 was added to a culture containing low concentrations of IL-3 (1 U/ml, 4 U/ml), which had little effect on colony formation, the number of total colonies formed by the spleen cells and bone marrow cells of 5-FU-treated mice increased significantly. The combination of BSF-2 and 40 U/ml of IL-3 resulted in a significant enlargement of GMM colonies. Thus, BSF-2 appears to enhance the sensitivity of multipotential hemopoietic progenitors to IL-3.

Analysis of interleukin 6 receptor and gp130 expressions and proliferative capability of human CD34+ cells.

We recently demonstrated that stimulation of gp130 by a combination of soluble interleukin 6 receptor (sIL-6R) and IL-6 but not IL-6 alone significantly stimulates the ex vivo expansion of primitive hematopoietic progenitors and the generation of erythroid cells from human CD34+ cells in the presence of stem cell factor (SCF). Here, we show that gp130 is found low positively on most CD34+ cells, whereas IL-6R is expressed on only 30-50% of these cells. Although most of the colonies generated from FACS-sorted CD34+IL-6R+ cells were granulocyte/macrophage (GM) colonies, CD34+IL-6R- cells gave rise to various types of colonies, including erythroid bursts, GM, megakaryocytes, and mixed colonies in methylcellulose culture with a combination of IL-6, sIL-6R, and SCF. Similar results were obtained in culture supplemented with a combination of IL-3, IL-6, SCF, granulocyte colony-stimulating factor, erythropoietin, and thrombopoietin. A limiting dilution analysis of long-term culture-initiating cells (LTC-IC) showed that the CD34+IL-6R- cells contained a larger number of LTC-IC than did the CD34+IL-6R+ cells. In a serum-free suspension of CD34+IL-6R- cells, the addition of sIL-6R to the combination of IL-6 and SCF dramatically increased the total and multipotential progenitors, whereas CD34+IL-6R+ cells failed to do so under the same conditions. These results indicate that most of the erythroid, megakaryocytic, and primitive human hematopoietic progenitors are included in the IL-6R- populations, and the activation of gp130 on these progenitors can be achieved by a complex of IL-6-sIL-6R, but not by IL-6 alone. The present culture system using IL-6, sIL-6R, and SCF may provide a novel approach for ex vivo expansion of human primitive hematopoietic progenitors.

Erythropoietin-independent erythrocyte production: signals through gp130 and c-kit dramatically promote erythropoiesis from human CD34+ cells.

Erythropoietin (EPO) is the primary humoral regulator of erythropoiesis and no other factor has previously been reported to support proliferation and terminal maturation of erythroid cells from hemopoietic stem cells. Here we show that stimulation of glycoprotein (gp130) by a combination of recombinant human soluble interleukin 6 receptor (sIL-6R) and IL-6 but not sIL-6R or IL-6 alone can support proliferation, differentiation, and terminal maturation of erythroid cells in the absence of EPO from purified human CD34+ cells in suspension culture containing stem cell factor (SCF). A number of erythroid bursts and mixed erythroid colonies also developed in methylcellulose culture under the same combination. The addition of anti-gp130 monoclonal antibodies but not anti-EPO antibody to the same culture completely abrogated the generation of erythroid cells. These results clearly demonstrate that mature erythroid cells can be emerged from hemopoietic progenitors without EPO in vitro. Together with the previous reports that human sera contain detectable levels of sIL-6R, IL-6, and SCF, current data suggest that gp130 signaling in association with c-kit activation may play a role in human erythropoiesis in vivo.

Prescription trends for treatment of paediatric gastroenteritis at a Japanese hospital between 1997 and 2007.

OBJECTIVE: We aimed to investigate recent trends in prescriptions for the treatment of paediatric gastroenteritis in Japan over a 10-year period (1997-2007). METHODS: In this retrospective cohort study, we collected data for 2295 prescriptions for 1241 putative cases of paediatric gastroenteritis, which were treated between 1997 and 2007 at Hamamatsu University Hospital, Hamamatsu, Japan. RESULTS: The most frequently prescribed drugs were probiotics (n = 621), followed by anti-emetics (n = 474). In most years between 1997 and 2007, more cases were treated with probiotics than with any other drug type (30.6-63.3% of cases), with the percentage increasing between 2005 and 2007. In contrast, the frequencies of anti-emetic and antipyretic prescriptions remained fairly stable, and prescriptions for antibiotics decreased slightly over the study period. Anti-emetics were commonly used in this hospital. CONCLUSION: Although experimental evidence upon which to base recommendations is lacking, Japanese evidence-based guidelines are critical for improving the quality of treatment of paediatric gastroenteritis.

The Bcr-Abl kinase inhibitor INNO-406 induces autophagy and different modes of cell death execution in Bcr-Abl-positive leukemias.

Bcr-Abl tyrosine kinase (TK) inhibitors are promising therapeutic agents for Bcr-Abl-positive (Bcr-Abl(+)) leukemias. Although they are known to promote caspase-mediated apoptosis, it remains unclear whether caspase-independent cell death-inducing mechanisms are also triggered. Here we demonstrated that INNO-406, a second-generation Bcr-Abl TK inhibitor, induces programmed cell death (PCD) in chronic myelogenous leukemia (CML) cell lines through both caspase-mediated and caspase-independent pathways. The latter pathways include caspase-independent apoptosis (CIA) and necrosis-like cell death (CIND), and the cell lines varied regarding which mechanism was elicited upon INNO-406 treatment. We also observed that the propensity toward CIA or CIND in cells was strongly associated with cellular dependency on apoptosome-mediated caspase activity. Cells that undergo CIND have a high apoptosome activity potential whereas cells that undergo CIA tend to have a lower potential. Moreover, we found that INNO-406 promotes autophagy. When autophagy was inhibited with chloroquine or gene knockdown of beclin1 by shRNA, INNO-406-induced cell death was enhanced, which indicates that the autophagic response of the tumor cells is protective. These findings suggest new insights into the biology and therapy of Bcr-Abl(+) leukemias.

NOD/Shi-scid IL2rgamma(null) (NOG) mice more appropriate for humanized mouse models.

"Humanized mice," in which various kinds of human cells and tissues can be engrafted and retain the same functions as in humans, are extremely useful because human diseases can be studied directly. Using the newly combined immunodeficient NOD-scid IL2rgamma(null) mice and Rag2(null) IL2rgamma(null) humanized mice, it has became possible to expand applications because various hematopoietic cells can be differentiated by human hematopoietic stem cell transplantation, and the human immune system can be reconstituted to some degree. This work has attracted attention worldwide, but the development and use of immunodeficient mice in Japan are not very well known or understood. This review describes the history and characteristics of the NOD/Shi-scid IL2rgamma(null) (NOG) and BALB/cA-Rag2(null) IL2rgamma(null) mice that were established in Japan, including our unpublished data from researchers who are currently using these mice. In addition, we also describe the potential development of new immunodeficient mice that can be used as humanized mice in the future.

Outcome of risk-based therapy for infant acute lymphoblastic leukemia with or without an MLL gene rearrangement, with emphasis on late effects: a final report of two consecutive studies, MLL96 and MLL98, of the Japan Infant Leukemia Study Group.

We evaluated the efficacy of a treatment strategy in which infants with acute lymphoblastic leukemia (ALL) were stratified by their MLL gene status and then assigned to different risk-based therapies. A total of 102 patients were registered on two consecutive multicenter trials, designated MLL96 and MLL98, between 1995 and 2001. Those with a rearranged MLL gene (MLL-R, n=80) were assigned to receive intensive chemotherapy followed by hematopoietic stem cell transplantation (HSCT), while those with germline MLL (MLL-G, n=22) were treated with chemotherapy alone. The 5-year event-free survival (EFS) rate for all 102 infants was 50.9% (95% confidence interval, 41.0-60.8%). The most prominent late effect was growth impairment, observed in 58.9% of all evaluable patients in the MLL-R group. This plan of risk-based therapy appears to have improved the overall prognosis for infants with ALL, compared with previously reported results. However, over half the events in patients with MLL rearrangement occurred before the instigation of HSCT, and that HSCT-related toxic events comprised 36.3% (8/22) of post-transplantation events, suggesting that further stratification within the MLL-R group and the development of more effective early-phase intensification chemotherapy will be needed before the full potential of this strategy is realized.

Hemopoietic colony-forming cells in umbilical cord blood with extensive capability to generate mono- and multipotential hemopoietic progenitors.

We report identification of a unique class of human hemopoietic colony-forming cells with extensive ability to generate progenitors for secondary colonies. Mononuclear cells isolated from human umbilical cord blood formed colonies consisting of 40-500 blast cells after 25 d of incubation in methylcellulose culture in the presence of erythropoietin and medium conditioned by phytohemagglutinin-stimulated leukocytes. Replating of these blast cell colonies revealed that 100% of the primary colonies had the ability to generate secondary colonies, including multipotential colonies. These colonies could be distinguished from other hemopoietic colonies in situ by the complete absence of signs of terminal differentiation. Replating of granulocyte-erythrocyte-macrophage-megakaryocyte (GEMM) colonies, consisting of an average of 2 x 10(4) cells, revealed less capacity for secondary colony formation. This human blast cell colony assay may provide a method for quantitation of more primitive hemopoietic stem cells than progenitors for GEMM colonies (CFU-GEMM) in man.

Erythroid progenitors differentiate and mature in response to endogenous erythropoietin.

We reported previously that stimulation of glycoprotein 130 (gp130) by a combination of human IL-6 and soluble IL-6 receptor (sIL-6R) could support proliferation, differentiation, and terminal maturation of erythroid cells in the absence of erythropoietin (EPO) from human CD34(+) cells in culture with stem cell factor (SCF). This observation suggested that differentiation of hematopoietic stem/progenitor cells to erythroid cells progressed according to an intrinsic program and that EPO receptor (EPOR) could be replaced by other cytokine receptors. In other words, EPOR appeared to be dispensable for erythropoiesis. Here we examined the role of EPOR in erythropoiesis stimulated by SCF, sIL-6R, and IL-6. Surprisingly, reduction of EPOR expression using antisense oligodeoxynucleotides suppressed erythropoiesis stimulated not only by SCF and EPO, but also by SCF, sIL-6R, and IL-6. EPO mRNA was detected in erythroid cells but not myeloid cells cultured in the presence of SCF, sIL-6R, and IL-6. Furthermore, high concentrations of anti-EPO-neutralizing antibody abrogated erythropoiesis in cultures without exogenous EPO. Based on these results, we suggest that erythroid progenitors themselves secrete EPO and that they have the potential to differentiate and mature in response to this endogenous EPO.

Expansion of human NOD/SCID-repopulating cells by stem cell factor, Flk2/Flt3 ligand, thrombopoietin, IL-6, and soluble IL-6 receptor.

Here, we demonstrate a significant ex vivo expansion of human hematopoietic stem cells capable of repopulating in NOD/SCID mice. Using a combination of stem cell factor (SCF), Flk2/Flt3 ligand (FL), thrombopoietin (TPO), and a complex of IL-6 and soluble IL-6 receptor (IL-6/sIL-6R), we cultured cord blood CD34(+) cells for 7 days and transplanted these cells into NOD/SCID mice. Bone marrow engraftment was judged successful when recipient animals contained measurable numbers of human CD45(+) cells 10-12 weeks after transplantation. When cells were cultured with SCF+FL+TPO+IL-6/sIL-6R, 13 of 16 recipients were successfully engrafted, and CD45(+) cells represented 11.5% of bone marrow cells in engrafted recipients. Cells cultured with a subset of these factors were less efficiently engrafted, both as measured by frequency of successful transplantations and prevalence of CD45(+) cells. In animals receiving cells cultured with all 4 factors, human CD45(+) cells represented various lineages, including a large number of CD34(+) cells. The proportion of CD45(+) cells in recipient marrow was 10 times higher in animals receiving these cultured cells than in those receiving comparable numbers of fresh CD34(+) cells, and the expansion rate was estimated at 4.2-fold by a limiting dilution method. Addition of IL-3 to the cytokine combination abrogated the repopulating ability of the expanded cells. The present study may provide a novel culture method for the expansion of human transplantable hematopoietic stem cells suitable for clinical applications.

Suppression of STAT5 functions in liver, mammary glands, and T cells in cytokine-inducible SH2-containing protein 1 transgenic mice.

Various cytokines utilize Janus kinase (JAK) and the STAT (signal transducers and activators of transcription) family of transcription factors to carry out their biological functions. Among STATs, two highly related proteins, STAT5a and STAT5b, are activated by various cytokines, including prolactin, growth hormone, erythropoietin, interleukin 2 (IL-2), and IL-3. We have cloned a STAT5-dependent immediate-early cytokine-responsive gene, CIS1 (encoding cytokine-inducible SH2-containing protein 1). In this study, we created CIS1 transgenic mice under the control of a beta-actin promoter. The transgenic mice developed normally; however, their body weight was lower than that of the wild-type mice, suggesting a defect in growth hormone signaling. Female transgenic mice failed to lactate after parturition because of a failure in terminal differentiation of the mammary glands, suggesting a defect in prolactin signaling. The IL-2-dependent upregulation of the IL-2 receptor alpha chain and proliferation were partially suppressed in the T cells of transgenic mice. These phenotypes remarkably resembled those found in STAT5a and/or STAT5b knockout mice. Indeed, STAT5 tyrosine phosphorylation was suppressed in mammary glands and the liver. Furthermore, the IL-2-induced activation of STAT5 was markedly inhibited in T cells in transgenic mice, while leukemia inhibitory factor-induced STAT3 phosphorylation was not affected. We also found that the numbers of gamma delta T cells, as well as those of natural killer (NK) cells and NKT cells, were dramatically decreased and that Th1/Th2 differentiation was altered in transgenic mice. These data suggest that CIS1 functions as a specific negative regulator of STAT5 in vivo and plays an important regulatory role in the liver, mammary glands, and T cells.

Chimeric cytokine receptor can transduce expansion signals in interleukin 6 receptor alpha (IL-6Ralpha)-, IL-11Ralpha-, and gp130-low to -negative primitive hematopoietic progenitors.

We generated transgenic mice expressing chimeric receptors, which comprise extracellular domains of the human granulocyte-macrophage colony-stimulating factor (hGM-CSF) receptor and transmembrane and cytoplasmic domains of the mouse leukemia inhibitory factor receptor. In suspension cultures of lineage-negative (Lin(-)), 5-fluorouracil-resistant bone marrow cells of the transgenic mice, a combination of hGM-CSF and stem cell factor (SCF) induced exponential expansions of mixed colony-forming unit. The combination of hGM-CSF and SCF was effective on enriched, Lin(-)Sca-1(+)c-kit(+) progenitors and increased either mixed colony-forming unit or cobblestone area-forming cells. In case of stimulation with hGM-CSF and SCF, interleukin-6 (IL-6) and SCF, or IL-11 and SCF, the most efficient expansion was achieved with hGM-CSF and SCF. When Lin(-)Sca-1(+)c-kit(+)CD34(-) further enriched progenitors were clone sorted and individually incubated in the presence of SCF, hGM-CSF stimulated a larger number of cells than did IL-6, IL-6 and soluble IL-6 receptor (IL-6R), or IL-11. These data suggest the presence of IL-6Ralpha-, IL-11Ralpha-, and gp130-low to -negative primitive hematopoietic progenitors. Such primitive progenitors are equipped with signal transduction molecules and can expand when these chimeric receptors are genetically introduced into the cells and stimulated with hGM-CSF in the presence of SCF.

A human GM-CSF receptor expressed in transgenic mice stimulates proliferation and differentiation of hemopoietic progenitors to all lineages in response to human GM-CSF.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) mainly stimulates proliferation and maturation of myeloid progenitor cells. Although the signal transduction pathways triggered by GM-CSF receptor (GMR) have been extensively characterized, the roles of GMR signals in differentiation have remained to be elucidated. To examine the relationship between receptor expression and differentiation of hemopoietic cells, we used transgenic mice (Tg-mice) that constitutively express human (h) GMR at almost all stages of hemopoietic cell development. Proliferation and differentiation of hemopoietic progenitors in bone marrow cells from these Tg-mice were analyzed by methylcellulose colony formation assay. High affinity GMR interacts with GM-CSF in a species-specific manner, therefore one can analyze the effects of hGMR signals on differentiation of mouse hemopoietic progenitors using hGM-CSF. Although mouse (m) GM-CSF yielded only GM colonies, hGM-CSF supported various types of colonies including GM, eosinophil, mast cell, erythrocyte, megakaryocyte, blast cell, and mixed hemopoietic colonies. Thus, the effects of hGM-CSF on colony formation more closely resembled mIL-3 than those of mGM-CSF. In addition, hGM-CSF generated a much larger number of blast cell colonies and mixed cell colonies than did mIL-3. hGM-CSF also generated erythrocyte colonies in the absence of erythropoietin. Therefore, GM-CSF apparently has the capacity to promote growth of cells of almost all hemopoietic cell lineages, if functional hGMR is present.

SN-1, a novel leukemic cell line with t(11;16)(q23;p13): myeloid characteristics and resistance to retinoids and vitamin D3.

The MLL gene is fused with the cAMP-responsive element binding protein-binding protein (CBP) gene in t(11;16)(q23;p13), which has been reported to be associated with therapy-related acute leukemia. We established a novel myeloid cell line, SN-1, from a patient with T-cell acute lymphoblastic leukemia with t(11;16)(q23;p13) having in-frame MLL-CBP fusion transcripts. The majority of the SN-1 cells were positive for myeloperoxidase when examined using an electron microscope and expressed CD13, CD33, CD56, and HLA-DR antigens, but not CD7, CD10, CD19, CD34, or CD41 antigens, suggesting that these cells are of myeloid origin. SN-1 cells underwent functional and morphological differentiation when treated with actinomycin D or sodium butyrate, but not with all-trans-retinoic acid (ATRA) or 1alpha,25-dihydroxyvitamin D3 (VD3). Exposure of SN-1 cells to ATRA hardly affected cell growth and differentiation, whereas the growth of HL-60 and NB4 cells treated with ATRA was effectively inhibited, and differentiation into mature granulocytes was induced. SN-1 cells were relatively insensitive to VD3 with respect to inhibiting the cell growth and inducing the ability to reduce nitroblue tetrazolium, lysozyme activity, and morphological differentiation, although the expression of CD11b was slightly induced by VD3. These results suggest that the cell line was impaired in the signal transduction systems of ATRA and VD3. This cell line should be useful for the study of the role of CBP as a transcriptional regulator in leukemia differentiation and for the functional analysis of the MLL-CBP fusion gene, which will provide new insights into leukemogenesis caused by 11q23 translocations.

CD146 is a novel marker for highly tumorigenic cells and a potential therapeutic target in malignant rhabdoid tumor.

Malignant rhabdoid tumor (MRT) is a rare, highly aggressive pediatric malignancy that primarily develops during infancy and early childhood. Despite the existing standard of intensive multimodal therapy, the prognosis of patients with MRT is dismal; therefore, a greater understanding of the biology of this disease is required to establish novel therapies. In this study, we identified a highly tumorigenic sub-population in MRT, based on the expression of CD146 (also known as melanoma cell adhesion molecule), a cell adhesion molecule expressed by neural crest cells and various derivatives. CD146+ cells isolated from four MRT cell lines by cell sorting exhibited enhanced self-renewal and invasive potential in vitro. In a xenograft model using immunodeficient NOD/Shi-scid IL-2Rγ-null mice, purified CD146+ cells obtained from MRT cell lines or a primary tumor exhibited the exclusive ability to form tumors in vivo. Blocking of CD146-related mechanisms, either by short hairpin RNA knockdown or treatment with a polyclonal antibody against CD146, effectively suppressed tumor growth of MRT cells both in vitro and in vivo via induction of apoptosis by inactivating Akt. Furthermore, CD146 positivity in immunohistological analysis of 11 MRT patient samples was associated with poor patient outcomes. These results suggest that CD146 defines a distinct sub-population in MRT with high tumorigenic capacity and that this marker represents a promising therapeutic target.

Cloning and expression of human B cell-specific transcription factor BACH2 mapped to chromosome 6q15.

The transcription factor Bach2, a member of the BTB-basic region leucine zipper (bZip) factor family, binds to a 12-O-tetradecanoylphorbol-13-acetate (TPA)-responsive element and the related Maf-recognition element (MARE) by forming homodimers or heterodimers with Maf-related transcription factors. Bach2 regulates transcription by binding to these elements. To understand the function in hematopoiesis, we isolated a cDNA clone for human Bach2 (BACH2) encoding a protein of 841 amino acid residues with a deduced amino acid sequence having 89.5% identity to mouse homolog. Among human hematopoietic cell lines, BACH2 is expressed abundantly only in some B-lymphocytic cell lines. RT-PCR analysis of hematopoietic cells revealed that BACH2 mRNA is expressed in primary B-cells. Enforced expression of BACH2 in a human Burkitt cell line, RAJI that does not express endogenous BACH2, resulted in marked reduction of clonogenic activity, indicating that BACH2 possesses an inhibitory effect on cell proliferation. By fluorescent in situ hybridization, the BACH2 gene was localized to chromosome 6q15. Because deletion of the long arm of chromosome 6 (6q) is one of the commonest chromosomal alterations in human B-cell lymphoma, we examined for the loss of heterozygosity (LOH) of the BACH2 gene in human B-cell non-Hodgkin's lymphomas (NHL). Among 25 informative cases, five (20%) showed LOH. These results indicate that BACH2 plays important roles in regulation of B cell development.

Extensive brain hemorrhage and embryonic lethality in a mouse null mutant of CREB-binding protein.

CREB-binding protein (CBP) is a transcriptional co-activator which is required by many transcription factors. Rubinstein-Taybi syndrome (RTS), which is an autosomal dominant syndrome characterized by abnormal pattern formation, is associated with mutations in the human CBP gene. Various abnormalities occur at high frequency in the skeletal system of heterozygous Cbp-deficient mice, but some features of RTS such as cardiac anomalies do not, suggesting that some symptoms of RTS are caused by a dominant-negative mechanism. Here we report the characterization of homozygous Cbp-deficient mice. Homozygous mutants died around E10.5-E12.5, apparently as a result of massive hemorrhage caused by defective blood vessel formation in the central nervous system, and exhibited apparent developmental retardation as well as delays in both primitive and definitive hematopoiesis. Cbp-deficient embryos exhibited defective neural tube closure which was similar to those observed in twist-deficient embryos. However, a decrease in the level of twist expression was not observed in Cbp-deficient embryos. Anomalous heart formation, a feature of RTS patients and mice mutated in the CBP-related molecule, p300, was not observed in Cbp-deficient embryos. Since both Cbp and p300 are ubiquitously expressed in embryonic tissues including the developing heart, these results suggest that cardiac anomalies observed in RTS patients may be caused by a dominant negative effect of mutant CBP.

Therapy-related myelodysplastic syndrome in childhood: a retrospective study of 36 patients in Japan.

We report here a retrospective analysis of 36 children with therapy-related myelodysplastic syndrome (t-MDS) diagnosed between 1990 and 1999 in Japan. Their median age was 7.7 years and the median latency period for the development of t-MDS was 38.5 months. The primary tumors were hematologic in 15 of the cases and nonhematologic in 21. Chromosomal abnormalities were detected in 32/34(94%) patients: abnormalities of chromosomes 5and/or 7 in 41% and notably, 11q23 abnormalities in 31%. The prognosis of children with t-MDS was very poor as compared to children with primary MDS (5 year survival: 16% versus 54%, p<0.0001).