Takafumi Miyata

Clinicopathologic analysis of 6 lymphomatoid gastropathy cases: expanding the disease spectrum to CD4-CD8+ cases.

Lymphomatoid gastropathy, which was first reported in 2010, is a rare NK-cell proliferation of cyCD3+, CD4−, CD5−, CD8−, CD56+ phenotypes with unknown etiology. The diagnosis is challenging, as there is histopathologic similarity to malignant lymphoma. In the 2010 report on 10 cases, all lesions were located in the stomach, and all regressed without any therapy. In the present study, we analyzed 6 cases of lymphomatoid gastropathy by investigating the clinicopathologic, immunohistochemical, and molecular findings. Endoscopic and morphologic appearances of all cases were consistent with previous reports, but 2 cases showed previously unreported unique immunophenotypes of CD4−CD8+. Three of 6 patients underwent lower gastrointestinal examination (1 case underwent double-balloon endoscopic examination), but no patient had lesions in the lower gastrointestinal tract. No obvious difference of histology was found between the cases of CD4-CD8-typical phenotype and ones of CD4−CD8+ phenotype. Both cases had similar clinical behavior as the other 4 cases, implying that the spectrum of the disease is broader than initially thought. Careful clinical and endoscopic follow-up is required for the diagnosis of lymphomatoid gastropathy, and additional case studies and molecular studies are warranted to further investigate the pathophysiology of this peculiar benign mimic of lymphoma.

Nonmonotonic dx2-y2-Wave Superconductivity in Electron-Doped Cuprates Viewed from the Strong-Coupling Side

Applying a variational Monte Carlo method to a two-dimensional t – J model, we study the nonmonotonic d x 2 - y 2 -wave superconductivity observed by Raman scattering and angle-resolved photoelectr...

Elevation of serum interleukins 8, 4, and 1β levels in patients with gastrointestinal low-grade B-cell lymphoma

Proinflammatory cytokines that are produced by helper T cells (Th) regulate immune reactions, facilitate class switching of B cells, and prolong the lifespan of B and T cells. Eradication therapy using antibiotics is sometimes effective against gastrointestinal (GI) malignant lymphoma, suggesting that the tumor development or progression is affected by the inflammatory microenvironment. In the present study, serum samples from 148 patients with various subtypes of malignant lymphoma were tested for 11 proinflammatory Th1/Th2 cytokines. In the comparison by subtype or GI lesions, serum interleukin (IL)-8 (P = 6.7E−05), IL-4 (P = 7.5E−05), and IL-1β (P = 0.0043) levels showed significant differences among subtypes, being particularly elevated in follicular lymphomas (FL) and mucosa-associated lymphoid tissue (MALT) lymphomas. Serum IL-8 levels were elevated in GI-FL and MALT lymphomas, and serum IL-4 and IL-1 β levels were elevated in MALT lymphomas. These findings show that GI low-grade B-cell lymphoma could develop against the background of an inflammatory microenvironment. Thus, these cytokines may be useful as diagnostic markers and could provide new insights into tumor development.

A heuristic search algorithm based on subspaces for PageRank computation

We studied a fast algorithm for the large-scale computation of PageRank. PageRank is what the Google search engine uses to simulate the importance of web pages. It is defined by the eigenvector of a particular stochastic matrix related to the graphs of web pages. The power method is the typical means to compute the eigenvector, while the Krylov subspace method shows faster convergence, which can be regarded as a two-step algorithm. The first step predicts the eigenvector, and the second step corrects the predicted result. More precisely, the power method is first iterated to compute the eigenvector approximately. Secondly, a Krylov subspace spanned by the approximations is searched for a better approximate eigenvector in terms of minimizing a residual. To get a better approximation efficiently, we consider using subspaces not only at the second step but also at the first step. Specifically, a Krylov subspace is first used to compute an approximate eigenvector, by which another subspace is expanded. Secondly, this non-Krylov subspace is searched for a better approximate eigenvector that minimizes its residual over the subspace. This paper describes a heuristic search algorithm iterating the two steps alternately and presents its efficient implementation. Experimental results with huge Google matrices illustrate improvements in performance of the algorithm.

Self-consistent field model simulations for statistics of amorphous polymer chains in crystalline lamellar structures

We calculate statistical properties of amorphous polymer chains between crystalline lamellae by self-consistent field model simulations. In our model, an amorphous subchain is modelled as a polymer chain of which ends are grafted onto the crystal-amorphous interfaces. The crystal-amorphous interfaces are expressed as impenetrable surfaces. We incorporate the interaction between segments to satisfy the incompressible condition for the segment density field. The simulation results show that amorphous polymer chains feel thin potential layers, which are mainly repulsive, near the crystal-amorphous interfaces. The impenetrable and incompressible conditions affect the statistics of polymer chains and the chain statistics becomes qualitatively different from the ideal Gaussian chain statistics without any constraints. We show the effects of the system size and the graft density to statistical quantities. We also show that the tie subchain statistics obey rather simple statistics.

Performance modeling of multishift QR algorithms for the parallel solution of symmetric tridiagonal eigenvalue problems

Multishift QR algorithms are efficient for solving the symmetric tridiagonal eigenvalue problem on a parallel computer. In this paper, we focus on three variants of the multishift QR algorithm, namely, the conventional multishift QR algorithm, the deferred shift QR algorithm and the fully pipelined multishift QR algorithm, and construct performance models for them. Our models are designed for shared-memory parallel machines, and given the basic performance characteristics of the target machine and the problem size, predict the execution time of these algorithms. Experimental results show that our models can predict the relative performance of these algorithms to the accuracy of 10% in many cases. Thus our models are useful for choosing the best algorithm to solve a given problem in a specified computational environment, as well as for finding the best value of the performance parameters.