Seung-Kyu Park | PubMed Health

PubMed2002

Preparation of microspheres by an emulsification-complexation method.

Microspheres were prepared by complexation of a cationic polymer, polyquaternium-24, and an anionic surfactant, sodium lauryl sulfate (SLS). The cationic polymer solution was emulsified in dimethylsiloxane to give water in silicone emulsion (W/Si), and it was used as a template for the formation of microspheres. The emulsion was dispersed into the SLS solution. In this process, two kinds of droplets, silicone dropletes and microspheres composed of the cationic polymer and SLS, were formed, evidenced by X-ray energy dispersive spectra. The mean diameter of the microspheres was reduced from 105.7 to 64.8 mum as the stirring rate for W/Si preparation increased from 300 to 1000 rpm. It is believed that water droplets in W/Si emulsion, when exposed to SLS solution, could be solidified by the complexation of the cationic polymer and the anionic surfactant.

Dimethylpolysiloxanes↗

PubMed2002

Atypical teratoid/rhabdoid tumor of the central nervous system: clinico-pathological study.

Atypical teratoid/rhabdoid tumor (AT/RT) is a new entity among malignant pediatric brain tumors. This study was performed to investigate the clinicopathologic and cytogenetic features of the tumor. Five cases from a series of the brain tumors were studied. Clinical features of the patients were assessed with age, sex, location of the tumors, treatments and survival periods. Histopathologic features were analyzed by routine HE stain and immunohistochemical stains for epithelial membrane antigen, cytokeratin, vimentin, smooth muscle actin, desmin, GFAP, S-100 protein, neurofilament protein, synaptophysin and alpha-feto protein. Cytogenetic studies for karyotype analysis and fluorescent in situ hybridization were available in three cases. Mean age of patients was 5.6 years, and maximal survival periods were less than 13 months despite surgical and radiation therapy. The tumors were located in infratentorial and supratentorial areas. Histopathologically, the tumors were chiefly composed of rhabdoid cells, modified rhabdoid cells and undifferentiated small cells, mixed with epithelial, mesenchymal, and neural tumor-like areas. These polyphenotypic features of the tumor cells were supported by diverse immunoreaction. Monosomy of chromosome 22 was demonstrated in two cases of the tumor. These results suggest that AT/RT may be a unique clinicopathologic entity, and histopathologic diagnosis of it should be made judiciously by differentiating other polymorphous tumors of the brain.

Brain Neoplasms↗