Embryonic development of multilineage hematopoiesis requires the precisely regulated expression of lineage-specific transcription factors, including AML-1 (encoded by Runx1; also known as CBFA-2 or PEBP-2alphaB). In vitro studies and findings in human diseases, including leukemias, myelodysplastic syndromes and familial platelet disorder with predisposition to acute myeloid leukemia (AML), suggest that AML-1 has a pivotal role in adult hematopoiesis. However, this role has not been fully uncovered in vivo because of the embryonic lethality of Runx1 knockout in mice. Here we assess the requirement of AML-1/Runx1 in adult hematopoiesis using an inducible gene-targeting method. In the absence of AML-1, hematopoietic progenitors were fully maintained with normal myeloid cell development. However, AML-1-deficient bone marrow showed inhibition of megakaryocytic maturation, increased hematopoietic progenitor cells and defective T- and B-lymphocyte development. AML-1 is thus required for maturation of megakaryocytes and differentiation of T and B cells, but not for maintenance of hematopoietic stem cells (HSCs) in adult hematopoiesis.

The Notch genes play a key role in cellular differentiation. The significance of Notch1 during thymocyte development is well characterized, but the function of Notch2 is poorly understood. Here we demonstrate that Notch2 but no other Notch family member is preferentially expressed in mature B cells and that conditionally targeted deletion of Notch2 results in the defect of marginal zone B (MZB) cells and their presumed precursors, CD1d(hi) fraction of type 2 transitional B cells. Among Notch target genes, the expression level of Deltex1 is prominent in MZB cells and strictly dependent on that of Notch2, suggesting that Deltex1 may play a role in MZB cell differentiation.

Evi-1 has been recognized as one of the dominant oncogenes associated with murine and human myeloid leukemia. Here, we show that hematopoietic stem cells (HSCs) in Evi-1-deficient embryos are severely reduced in number with defective proliferative and repopulating capacity. Selective ablation of Evi-1 in Tie2(+) cells mimics Evi-1 deficiency, suggesting that Evi-1 function is required in Tie2(+) hematopoietic stem/progenitors. Conditional deletion of Evi-1 in the adult hematopoietic system revealed that Evi-1-deficient bone marrow HSCs cannot maintain hematopoiesis and lose their repopulating ability. In contrast, Evi-1 is dispensable for blood cell lineage commitment. Evi-1(+/-) mice exhibit the intermediate phenotype for HSC activity, suggesting a gene dosage requirement for Evi-1. We further demonstrate that disruption of Evi-1 in transformed leukemic cells leads to significant loss of their proliferative activity both in vitro and in vivo. Thus, Evi-1 is a common and critical regulator essential for proliferation of embryonic/adult HSCs and transformed leukemic cells.

Loss of heterozygosity (LOH), either with or without accompanying copy-number loss, is a cardinal feature of cancer genomes that is tightly linked to cancer development. However, detection of LOH is frequently hampered by the presence of normal cell components within tumor specimens and the limitation in availability of constitutive DNA. Here, we describe a simple but highly sensitive method for genomewide detection of allelic composition, based on the Affymetrix single-nucleotide-polymorphism genotyping microarray platform, without dependence on the availability of constitutive DNA. By sensing subtle distortions in allele-specific signals caused by allelic imbalance with the use of anonymous controls, sensitive detection of LOH is enabled with accurate determination of allele-specific copy numbers, even in the presence of up to 70%-80% normal cell contamination. The performance of the new algorithm, called "AsCNAR" (allele-specific copy-number analysis using anonymous references), was demonstrated by detecting the copy-number neutral LOH, or uniparental disomy (UPD), in a large number of acute leukemia samples. We next applied this technique to detection of UPD involving the 9p arm in myeloproliferative disorders (MPDs), which is tightly associated with a homozygous JAK2 mutation. It revealed an unexpectedly high frequency of 9p UPD that otherwise would have been undetected and also disclosed the existence of multiple subpopulations having distinct 9p UPD within the same MPD specimen. In conclusion, AsCNAR should substantially improve our ability to dissect the complexity of cancer genomes and should contribute to our understanding of the genetic basis of human cancers.

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Epstein-Barr virus (EBV)-DNA was prospectively analyzed in plasma and mononuclear cells (MNCs) from peripheral blood in patients with extranodal natural killer (NK)/T-cell lymphoma, nasal type, to evaluate the clinical significance for diagnosis, monitoring the tumor burden, and prognostication. Thirty-three patients were enrolled, and 32 were evaluable. Pretreatment plasma and MNC EBV-DNA was detectable in 14 (range, 50-71 000 copies/mL) and 6 patients (range, 20-780 copies/g DNA), respectively, and both were well correlated (r ‫؍‬ 0.8741, P < .0001). Detectable plasma EBV-DNA was associated with higher clinical stage (P ‫؍‬ .02), presence of B symptoms (P ‫؍‬ .02), worse performance status (P ‫؍‬ .02), and higher serum soluble IL-2 receptor level (P < .0001). Twentytwo patients attained complete response. Plasma EBV-DNA level was significantly higher in nonresponders than in responders (mean, 16 472 vs 2 645 copies/mL; P ‫؍‬ .02). Multivariate analysis showed clinical stage (hazard ratio, 9.0; 95% confidence interval, 1.8%-45.0%) and pretreatment plasma EBV-DNA (hazard ratio, 10.6; 95% confidence interval, 1.3%-87.0%) were significant prognostic factors. Threeyear overall survival of plasma EBV-DNA positive and negative patients was 42.9% and 94.4%, respectively (P ‫؍‬ .0009). Plasma was a preferable sample for this purpose in NK/T-cell lymphoma, nasal type, and EBV-DNA level was a good indicator for response and overall survival. (Blood. 2011;118(23):6018-6022)

The lymphocyte-specific Cas family protein Cas-L (Crk-associated substrate lymphocyte type) has been implicated to function in lymphocyte movement, mediated mainly by integrin signaling. However, its physiological role is poorly understood. In this study we analyzed the function of Cas-L in lymphocytes using gene-targeted mice. The mutant mice showed a deficit of marginal zone B (MZB) cells and a decrease of cell number in secondary lymphoid organs. An insufficient chemotactic response and perturbed cell adhesion were observed in Cas-L-deficient lymphocytes, suggesting that the aberrant localization was responsible for the deficit of MZB cells. Moreover, we found that lymphocyte trafficking was altered in Cas-L-deficient mice, which gave a potential reason for contraction of secondary lymphoid tissues. Thus, Cas-L affects homeostasis of MZB cells and peripheral lymphoid organs, which is considered to be relevant to impaired lymphocyte migration and adhesion.

Augmented reality (AR) has the potential to create compelling learning experiences. However, there are few research works exploring the design and evaluation of AR for educational settings. In our research, we treat AR as a type of multimedia that is situated in authentic environments and apply multimedia learning theory as a framework for developing our educational applications. We share our experiences in developing a handheld AR system and one specific use case, namely, situated vocabulary learning. Results of our evaluations show that we are able to create AR applications with good system usability. More importantly, our preliminary evaluations show that AR may lead to better retention of words and improve student attention and satisfaction.