Radiation therapy with UFT and low dose weekly cisplatin for nasopharyngeal carcinoma.

Objective: We conducted this study to determine the effectiveness and toxicity of chemoradiation therapy using UFT and low-dose cisplatin in 37 patients with nasopharyngeal carcinoma (NPC).

Patients And Methods: Between March 1999 and December 2001, 37 patients with newly diagnosed and histologically proven nasopharyngeal carcinoma treated in Department of Radiation Oncology, Asan Medical Center were enrolled in this protocol. Cisplatin was administered weekly, starting on day 1 of radiation therapy, as an intravenous infusion at 20 mg/m2 of body-surface area.

Chemoprevention of 4-NQO-induced oral carcinogenesis by co-administration of all-trans retinoic acid loaded microspheres and celecoxib.

All-trans retinoic acid (atRA) is one of the most potential chemopreventive agents for head and neck squamous cell carcinoma (HNSCC). However, the induced metabolism of atRA by cytochrome P450s in the liver limits its clinical applications. To overcome such limitation, we had developed atRA-loaded microspheres designed to release atRA for a long period.

Early evaluation of the response to radiotherapy of patients with squamous cell carcinoma of the head and neck using 18FDG-PET.

The aim was to evaluate the efficacy of positron emission tomography (PET) with 2-[F-18]fluoro-2-deoxy-d-glucose (FDG) in early discrimination of response to definitive radiotherapy (RT) in patients with squamous cell carcinoma of the head and neck (SCCHN). Twenty-four patients who underwent FDG-PET scans before and after radiotherapy for nondisseminated SCCHN at the Asan Medical Center between August 2001 and September 2002 were prospectively evaluated. Initial FDG-PET scans were performed within 1 month before RT, and follow-up FDG-PET scans were performed 1 month after completion of RT.

The effect of cellular retinoic acid binding protein-I expression on the CYP26-mediated catabolism of all-trans retinoic acid and cell proliferation in head and neck squamous cell carcinoma.

The aim of this study was to confirm if catabolism of all-trans retinoic acid (RA) is enhanced by type I cellular retinoic acid binding protein (CRABP-I) expression and to investigate the effect of this enhanced catabolism on cell proliferation of the head and neck squamous cell carcinoma (HNSCC) cell line, AMC-HN-7. We also analyzed the effects of CRABP-I on RA-induced retinoic acid receptor (RAR) activity. The expression of the CRABP-I in stably transfected AMC-HN-7 cell lines (HN7-BPIa and HN7-BPIb) resulted in a lower sensitivity to administered RA compared with that of controls in a clonogenic assay.

A study of moderately differentiated neuroendocrine carcinomas of the larynx and an examination of non-neoplastic larynx tissue for neuroendocrine cells.

Objectives/hypothesis: To determine the most appropriate terminology for neuroendocrine carcinomas (NEC) of the larynx, successive clinicopathologic studies are encouraged. The typical location and immunophenotype of laryngeal NEC raise a question of whether any precursor cells exist.

Study Design: Six patients with laryngeal NEC were analyzed.

Dynamical origin for the occurrence of asynchronous hyperchaos and chaos via blowout bifurcations.

We investigate the dynamical origin for the occurrence of asynchronous hyperchaos and chaos via blowout bifurcations in coupled chaotic systems. An asynchronous hyperchaotic or chaotic attractor with a positive or negative second Lyapunov exponent appears through a blowout bifurcation. It is found that the sign of the second Lyapunov exponent of the newly born asynchronous attractor, exhibiting on-off intermittency, is determined through competition between its laminar and bursting components.

Inhibition of tumor growth by biodegradable microspheres containing all-trans-retinoic acid in a human head-and-neck cancer xenograft.

Retinoids play essential roles in the regulation of cell differentiation and in the proliferation of various epithelial tissues, and atRA is one such active metabolite of retinoids. However, despite the known functions of atRA, its clinical applications are limited due to the induced metabolism by the specific cytochrome P-450s in the liver. To overcome the limitation, parenteral administration of atRA-loaded biodegradable microspheres, the PDLLA/PLE microspheres containing atRA, was suggested previously.

Mechanism for the intermittent route to strange nonchaotic attractors.

Intermittent strange nonchaotic attractors (SNAs) appear typically in quasiperiodically forced period-doubling systems. As a representative model, we consider the quasiperiodically forced logistic map and investigate the mechanism for the intermittent route to SNAs using rational approximations to the quasiperiodic forcing. It is found that a smooth torus transforms into an intermittent SNA via a phase-dependent saddle-node bifurcation when it collides with a new type of "ring-shaped" unstable set.

Fractal properties of robust strange nonchaotic attractors in maps of two or more dimensions.

We consider the existence of robust strange nonchaotic attractors in a simple class of quasiperiodically forced systems. Rigorous results are presented demonstrating that the resulting attractors are strange in the sense that their box-counting dimension D0 is larger than their information dimension D1 by 1 (i.e.

Characterization of the noise effect on weak synchronization.

We investigate the noise effect on weak synchronization in two coupled identical one-dimensional (1D) maps. Due to the existence of positive local transverse Lyapunov exponents, the weakly stable synchronous chaotic attractor (SCA) becomes sensitive with respect to the variation of noise intensity. To quantitatively characterize such noise sensitivity, we introduce a quantifier, called the noise sensitivity exponent (NSE).

In vivo biocompatibility studies of poly(D,L-lactide)/poly(ethylene glycol)-poly(L-lactide) microspheres containing all-trans-retinoic acid.

Biocompatibility studies of all-trans-retinoic acid (RA)-loaded microspheres were carried out after they were subcutaneously injected into rats. To characterize the inflammatory response to these microspheres, tissue reactions at the implantation site and cell types in the interstices of the microspheres were evaluated for 180 days. On the 15th day, the cross-sectional area of the fibrous capsules surrounding the implantation site of the RA-loaded microspheres was four times larger than that of the control microspheres.

Analysis of voice and quantitative measurement of glottal gap after thyroplasty type I in the treatment of unilateral vocal paralysis.

Thyroplasty type I is one of several surgical treatments in which improving the voice of unilateral vocal fold paralysis is the ultimate objective. The goal of the surgery is the medialization of the paralyzed vocal fold. The purpose of this study is to evaluate the effectiveness of thyroplasty type I through acoustical analysis, aerodynamic measures, and quantitative videostroboscopic measurements.

Retinoic acid 4-hydroxylase-mediated catabolism of all-trans retinoic acid and the cell proliferation in head and neck squamous cell carcinoma.

All-trans retinoic acid (RA) can be catabolized to polar metabolites by microsomal P450s (P450). The aim of this study was to confirm if retinoic acid 4-hydroxylase (CYP26) is a P450 induced by RA and to investigate the role of cellular RA binding proteins (CRABPs), using a slow catabolizer, AMC-HN-4, and a rapid catabolizer, AMC-HN-6. Also, we analyzed the effect of RA catabolism on cell proliferation of head and neck squamous cell carcinoma (HNSCC) in vitro and in vivo.

Solitary fibrous tumor of the parapharyngeal space: MR imaging findings.

We report the MR imaging findings of a solitary fibrous tumor involving the parapharyngeal space. The tumor was a well-circumscribed solid mass with a lobulated contour. It had the same signal intensity as the muscle on T1-weighted MR images, heterogeneously high signal intensity on T2-weighted images, and homogeneous strong enhancement after the administration of contrast material.

Characterization of the parameter-mismatching effect on the loss of chaos synchronization.

We investigate the effect of the parameter mismatch on the loss of chaos synchronization in coupled one-dimensional maps. Loss of strong synchronization begins with a first transverse bifurcation of a periodic saddle embedded in the synchronous chaotic attractor (SCA), and then the SCA becomes weakly stable. Because of local transverse repulsion of the periodic repellers embedded in the weakly stable SCA, a typical trajectory may have segments of arbitrary length that have positive local transverse Lyapunov exponents.