Long-time correlation in non-Markovian dephasing of an exciton-phonon system in InAs quantum dots.

We have observed a time-correlated frequency fluctuation in non-Markovian dephasing of excitons in InAs quantum dots using a six-wave mixing technique. In this measurement, the arrival times of the excitation pulses were controlled to eliminate the influence of Markovian dephasing and to measure the pure non-Markovian behavior. The experimental result shows that the time correlation of the frequency fluctuation due to exciton-phonon interactions was maintained in the quantum dots for over 10 ps. This long-time correlation is caused by the modification of the phonon coupling distribution.

Non-markovian dynamics of spectral narrowing for excitons in the layered semiconductor GaSe observed using optical four-wave mixing spectroscopy.

We have investigated non-markovian dephasing by using time-resolved and spectrally resolved four-wave mixing measurements in a layered semiconductor GaSe. When the time interval between the first and second excitation pulses is increased, photon echo spectra exhibit narrowing only in a regime of a few picoseconds. In the initial dephasing of these signals, fast damping is observed. The narrowing of the spectrally resolved signal is consistent with the Fourier transformation of the time-resolved signals. Spectral narrowing is crucial evidence of the transition from non-markovian to markovian dynamics. By comparing experimental data with calculation results based on the non-markovian theory, we have found that the correlation time of the exciton-phonon interaction is 1.1 ps.

Allogeneic hematopoietic stem cell transplant following chemotherapy containing l-asparaginase as a promising treatment for patients with relapsed or refractory extranodal natural killer/T cell lymphoma, nasal type.

The prognosis of advanced extranodal NK/T cell lymphoma (ENKTL) is poor. Allogeneic hematopoietic stem cell transplant (allo-HSCT) has been suggested to be a promising treatment for this disease, but its utility has yet to be established. Here we retrospectively analyzed five cases of ENKTL treated with allo-HSCT in our institute. After induction chemotherapy, disease status at allo-HSCT was second CR in three patients and refractory in two patients. All patients received a myeloablative conditioning regimen, and GVHD prophylaxis consisted of tacrolimus or cyclosporine with short-term methotrexate. Only one patient who received conventional induction chemotherapy developed severe complications, which needed long-term treatment, while others who received chemotherapy containing l-asparaginase did not have severe complications. There were no cases of treatment-related mortality, and all patients survived without disease for a median follow-up period of 1911 days. These results suggested that allo-HSCT following l-asparaginase-containing induction chemotherapy might improve the outcome of advanced ENKTL.

Optically enhanced emission of localized excitons in InxGa1-xN films by coupling to plasmons in a gold nanoparticle.

We report on strong site-selective enhancement of the emission of localized excitons in an InxGa1-xN film, induced by resonant coupling to a single plasmon confined in a gold nanoparticle. The particle was attached to an atomic-force-microscope probe and placed at the near-field distance of the surface. The observation is explained by the enhancement of the spontaneous emission recombination rate of the excitons due to the local increase in the photonic mode density near the metal particle. The interpretation is consistent with the intensity increase and lifetime shortening of the emission observed in the same film with deposited Au clusters. We show that the nanoscale roughness of the film is an important prerequisite of the efficient plasmonic enhancement.

Acquired hemophilia A with sigmoid colon cancer: successful treatment with rituximab followed by sigmoidectomy.

Acquired hemophilia A is a rare and potentially fatal condition of coagulopathy caused by autoantibodies against clotting factor VIII (factor VIII inhibitor). We report a case of a 63-year-old woman, who presented with a sudden onset of severe hemorrhagic tendency with exclusively prolonged activated partial thromboplastin time (APTT). She was diagnosed with acquired hemophilia A due to a decrease in factor VIII activity and a high titer of factor VIII inhibitor. Hemorrhage was well controlled by recombinant activated factor VII. Although the level of factor VIII inhibitor did not decline with prednisolone and cyclophosphamide, it became undetectable with rituximab. In parallel with controlling hemorrhage, malignancy, which may cause acquired hemophilia A, was searched for and sigmoid colon cancer was found. After the eradication of factor VIII inhibitor, surgical resection was performed uneventfully. Thereafter, acquired hemophilia A has been in complete remission without any additional therapy. The present case suggests the efficacy of rituximab for refractory acquired hemophilia A and the importance of the identification of underlying diseases that can cause acquired hemophilia A.

Light propagation from a fluorescent particle embedded in a photonic cluster of micrometer-sized dielectric spheres.

In self-assembled multilayer arrays of micrometer-sized spheres that include small amounts of fluorescent particles, unique six-dot-triangular and seven-dot-hexagonal patterns have been known to appear in the fluorescence microscopic images. Although it has been suggested that these two types of patterns correspond to local domain structures, i.e., face centered cubic (fcc) or hexagonal closed packed (hcp), no conclusive evidence has been provided to support this claim. In this study, we systematically investigated the relationship between the propagation patterns and the arrangement of the particles. Through a cross-check between an experiment using well-defined clusters fabricated by a micromanipulation technique and a rigorous calculation based on the expansion of vector spherical harmonics, we confirmed that the six-dot-triangular and seven-dot-hexagonal patterns correspond to the fcc and hcp domains, respectively. Further, we also found that the propagation patterns depend on the size of the clusters. As a result of a quantitative discussion on the light propagation in clusters with various sizes, it was clarified that a sufficient domain size is necessary for the appearance of clear triangular or hexagonal patterns.

Interlaboratory comparison of quantitative RT-PCR based detection for minimal residual disease in leukemias: a standardization approach in Japan.

Real-time quantitative polymerase chain reaction (RQ-PCR) has been accepted as integral part of the management of patients with hematologic malignancies. Whereas standardization efforts of RQ-PCR, initiated by Europe Against Cancer (EAC) group, have been gradually widespread in the world, Japanese laboratories use their individual protocol for RQ-PCR analysis. Therefore, we assessed the variability of quantitative results obtained from 4 different laboratories in Japan, including 3 companies and Tohoku University Hospital, using identical peripheral blood or bone marrow samples of patients in chronic myeloid leukemia (CML; n = 11) and acute myeloid leukemia (AML; n = 2). RQ-PCR was designed to quantify the copy numbers of disease-specific fusion chimeras; BCR-ABL (CML) and AML1-ETO (AML). In 5 out of 13 samples, the quantitative results from 4 laboratories varied more than 10 times (up to 712 times). Thus, we next sought to determine factors affecting the variability of RQ-PCR results across laboratories, by sending back RNA and cDNA samples from each company to Tohoku University, and they were further proceed to yield quantitative data. The main difference between companies and Tohoku University was probably due to the difference of blood separation method (Blood lysis or Ficoll-Hypaque). On the other hand, the variability among 4 laboratories was the most noticeable in the PCR step, mainly attributable to the difference of primer/probe sequence among laboratories. In conclusion, our analyses indicate the importance to limit both preanalytical (sample processing) and analytical (RQ-PCR) interlaboratory variability for RQ-PCR protocol, and the need of further efforts on standardization program in Japan.

Aggressive B-cell lymphoma with dual surface immunoglobulin light-chain expression.

Dual surface immunoglobulin light-chain expression in B-cell malignant neoplasm is a rare event, and has been predominantly reported in chronic lymphocytic leukemia. Herein, we report a case of aggressive B-cell lymphoma with kappa/lambda-dual surface immunoglobulin light-chain expression of a 69-year-old woman. The lymphoma cells were positive for CD5, CD19, CD20, HLA-DR, Ig kappa and Ig lambda. Southern blot analysis confirmed rearranged bands for both light chains with a monoclonal heavy chain rearrangement. She was treated with a combination of rituximab and CHOP regimen, but died of the progressive disease. To our knowledge, this is the first case of aggressive B-cell lymphoma showing dual kappa/lambda expression; the possible mechanisms of abnormal light chain expression are discussed.

Successful treatment of advanced extranodal NK/T cell lymphoma with unrelated cord blood transplantation.

Nasal natural killer (NK)/T cell lymphoma is a rare entity of non-Hodgkin's lymphoma which mostly occurs in East Asian countries. The advanced disease above clinical stage III is often refractory to the radiation and chemotherapies, remission is transient even if achieved, and median survival is about 12 months. Thus the prognosis of advanced NK/T cell lymphoma is generally poor, however, the promising results of allogeneic hematopoietic stem cell transplantation for advanced NK/T cell lymphoma have been recently reported. In most of these cases, stem cell sources were human leukocyte antigen (HLA) matched donors and alternative sources were seldom used. We report here a case of a 36-year-old woman who was diagnosed as having an extranodal NK/T cell lymphoma, nasal type. The patient achieved a complete remission after 2 cycles of chemotherapy including Carboplatin, Etoposide, Ifosfamide, and Dexamethasone, but 3-months later relapsed during the search for HLA-matched unrelated donors. She received unrelated cord blood transplantation (CBT) in the second remission achieved by a regimen containing L-asparaginase. The conditioning regimen was 12 Gy of total body irradiation, high-dose cytarabin and cyclophosphamide. FK506 and methotrexate were used for graft-versus-host disease (GVHD) prophylaxis. GVHD involving the intestine and the oral mucosa was observed, but improved without additional immunosuppressive therapies. The patient remains in remission 33 months after CBT. Cord blood thus could be an appropriate stem cell source for patients with advanced NK/T lymphoma who have no HLA matched donors.

Expression analyses and transcriptional regulation of mouse nucleolar spindle-associated protein gene in erythroid cells: essential role of NF-Y.

Nucleolar spindle-associated protein (NuSAP), a recently characterised microtubule-associated protein, appears to participate in cell cycle regulation. It has been demonstrated that NuSAP is expressed preferentially in the erythroid lineage in haematopoietic cells. To characterise its role in erythropoiesis, we examined the expression profile of the NuSAP gene. In fractionated murine erythroblasts, NuSAP mRNA was remarkably more abundant in the subset corresponding to immature erythroblasts (TER119(+)CD71(high)) than mature erythroblasts (TER119(+)CD71(low)), and it was significantly increased in TER119(+) cells from in vivo phlebotomised mice compared with control mice. Furthermore, during erythroid maturation of mouse erythroleukaemia (MEL) cells by dimethylsulfoxide, NuSAP mRNA was increased at 24-72 h. These results suggested that the NuSAP gene might contribute to the expansion of immature erythroblast pool. The regulatory mechanism of NuSAP gene was investigated using MEL cells. Sequence analysis revealed that NuSAP promoter has four CCAAT boxes, an Sp1 element, a GATA-like element, a CACCC element, a Myb element and lacks a TATA box. Promoter analyses demonstrated that duplicated CCAAT boxes located at -81/-85 and -30/-34 were essential for promoter activity. Furthermore, the promoter was trans-activated by NF-YA through these elements. These results suggest that NuSAP might play an important role in erythroid proliferation under the control of NF-Y.