Characteristics of plasma window with various channel diameters for accelerator applications

Plasma window is a feasible device as an atmosphere-vacuum interface, which can withstand energetic particle beams. It is, however, essential to enlarge the diameter to several tens of millimeters for actual beam passing in the accelerator applications. The pressure separation performance and discharge voltage V current I characteristics should be investigated in detail to design the plasma window for each purpose. Therefore, a cascade arc discharge device with a diameter of up to 20 mm was developed, and its characteristics as a function of diameter were examined. As a result, with an increase in the channel diameter, the discharge pressure that was achieved decreased, whose values were smaller compared with the values by the prediction formula, assuming the viscous gas flow with a constant plasma temperature. It showed that the bulk plasma temperature for the larger discharge channel was low because of the low-current density over the channel. Furthermore, the transition of the V-I slope was observed with an increase in the diameter.

Clear cell adenocarcinoma arising from umbilical endometriosis

Umbilical endometriosis is a very rare condition, and as far as we are aware, there have been no reported cases of its malignant transformation. Here, we report a case of clear cell adenocarcinoma arising from umbilical endometriosis in a 60-year-old woman who underwent hysterectomy for a uterine myoma at the age of 38, and who denied cyclic bleeding at the site of an umbilical cutaneous nodule correlating with menses until the age of 48. An umbilical tumor (3 cm diameter) was identified by magnetic resonance imaging and an abnormal accumulation was found only at the umbilical lesion by positron emission tomography examination. We observed endometriosis adjacent to the clear cell adenocarcinoma and transformation to carcinoma from endometriosis at the umbilical lesion histopathologically. Clear cell adenocarcinoma of the umbilicus was thought to have arisen from endometriosis; it expressed HER-2 protein and showed strong mesothelial characteristics immunohistochemically.

Cytotoxicity and characteristics of mitomycin C

In order to evaluate the cytotoxicity of mitomycin C (MMC), the effects of MMC on cell viability, cell cycle and cell surface structure were studied using Chang's cultured human conjunctival cells. A 4- or 2-min exposure to MMC at concentrations ranging from 0.002 to 0.04% decreased the cell viability. The cell number was remarkably reduced by exposure to MMC over 0.004%. MMC at a concentration higher than 0.001% arrested the DNA synthetic phase of the cell cycle. MMC even at a high concentration (0.04%) did not cause any direct alteration to the cell surface.

Usefulness of Scheimpflug photography to follow up Wilson's disease

A 24-year old female with ocular changes (Kayser-Fleischer ring and sunflower cataract) indicating Wilson's disease was followed up from 9 years of age with anterior eye segment image documentation by Scheimpflug photography. A low copper diet and systemic D-penicillamine were administered after the initial diagnosis of Wilson's disease. During a 15-year follow-up period, the yellowish/brown-colored granular opacification on the anterior lens capsule and/or in the capsule has mostly disappeared and instead, the same type of opacification has emerged on the posterior lens capsule, showing rather progressive changes compared with the initial findings. These changes which had developed in the lens during the past 15 years were difficult to detect by slit lamp examination alone, but they were clearly revealed by Scheimpflug slit images. To our knowledge this is the first case report on ocular changes disclosed through the application of a newly developed anterior eye segment examination. Ergo, Scheimpflug photography is valuable for follow-up studies of ocular complications seen in patients with Wilson's disease.

[Uncommon renal tumor in children]

We experienced six rare cases of solid renal tumor, which include two benign (CMN, MLCN) and four malignant tumors (CCSK 2, MRTK2). CMN is the most common benign solid tumor in the neonate. MLCN has typical US or CT findings manifested by multilocular cysts and thick wall septa. CCSK and MRTK are rare malignant neoplasms, which present characteristic clinical findings such as bone metastasis or intracranial metastasis. It is important for the radiologist to understand those characteristic clinical presentation of these tumors, because differential diagnosis is often impossible just on the basis of imaging.