嶋田 明

A 12-year-old girl presented with a large abdominal tumor. At surgery, a huge pedunculated extraluminal tumor was found arising from the greater curvature of the stomach and invading the surrounding structures, and there were also a submucosal tumor measuring 5 x 4 x 4 cm and multiple intramural nodules beside the main tumor. These lesions, which were removed with 1.0-cm surgical margins, were immunohistochemically positive for c-kit (CD117) and CD34. A diagnosis of gastrointestinal stromal tumor (GIST) was made. The huge size of the tumor (3.6 kg in weight and 36 x 25 x 25 cm in diameter), the invasion of the surrounding structures, and the increased mitotic figures indicated the GIST had malignant potential. Sequence analysis of the polymerase chain reaction product of RNAs from the tumor cells revealed a novel platelet-derived growth factor receptor alpha (PDGFRA) mutation, which would exhibit biologic consequences similar to those of the c-kit mutation. The patient underwent a 3-month course of imatinib mesylate as adjuvant chemotherapy because of the possible risk for tumor recurrence. She is now doing well without any evidence of recurrence or metastasis 25 months after the surgery. Only 9 cases of GIST have been reported in children, and a review of those cases revealed GISTs in children would be associated with a better prognosis than in adults and that one third of pediatric GISTs presented with intestinal obstruction in the newborn period.

Omenn syndrome (OS) is a rare primary immunodeficiency characterized by the presence of activated/oligoclonal T cells, eosinophilia, and the absence of circulating B cells. OS patients carry leaky mutations of recombination activating genes (RAG1 or RAG2) resulting in partial V(D)J recombination activity, whereas null mutations cause severe combined immunodeficiency with absence of mature T and B cells (T-B- SCID). Here we describe somatic mosaicism due to multiple second-site mutations in a patient with RAG1 deficiency. We found that he is homozygous for a single base deletion in the RAG1 gene, which results in frameshift and likely abrogates the protein function. However, the patient showed typical OS features. Molecular analysis revealed that several second-site mutations, all of which restored the RAG1 reading frame and resulted in missense mutations, were demonstrated in his T cells. These findings suggest that his revertant T-cell mosaicism is responsible for OS phenotype switched from T-B- SCID.

The prognosis for children with Wilms' tumor is reported to be excellent in those who are less than 2 years of age at diagnosis and who have a stage I/favorable-histology tumor with specimen weight less than 550 g. We report on a patient with Wilms' tumor who belonged to this group but who developed pulmonary metastases, and we discuss the diagnostic and therapeutic problems in such patients. The importance of careful evaluation of the renal sinus should be emphasized.

A transient myeloproliferative disorder (TMD) occurs in 10% of the infants with Down syndrome. While most cases resolve within a few months, in 20% of them TMDs are life-threatening or fatal. We encountered 4 patients with TMD, including 1 patient who died of liver failure and disseminated intravascular coagulation. Suspecting involvement of proinflammatory cytokines, we serially assayed them in patients' sera. Cytokines were significantly more abundant in patients than in controls. Interleukins 1 and 2, tumor necrosis factor alpha, interferon gamma, and granulocyte-macrophage colony-stimulating factor were greatly increased, especially in the infant who died. Sustained cytokinemia is likely to participate in TMD pathophysiology, and very high serum concentrations might predict a poor outcome.

The aim of this paper is to clear characteristics of the obsever based robot motion controller, which observer estimates disturbance torque and velocity.<BR>Generally, because of perturbation for moment of inertia, gravity, friction, and low-stiffness by its kinematic structures, robot motion becomes worse. It is well-known that the disturbance observer based controller is robust for not only actually disturbance but unknown perturbation. But we have never full knowledge of that observer, today.<BR>This paper describes the phisical means of the disturbance torque and velocity estimated observer, at first. Next, it shows how the observer which is used as way of attenuation for additional disturbance, gives influence to not-nominal model. And, I will show the influence of observer and phase-shift for chaging moment of inertia. And for low stiffness manipulators, I will clear that the observer having not-optimal poles gives worse result for motion.