Effect of particles with repulsive interactions enclosed in both rigid spherical shells and flexible fluid vesicles studied by Monte Carlo simulation.

Experimental observations indicate that the repulsion of particles is a factor that induces the transformation of vesicles containing multiple particles. Metropolis Monte Carlo simulations are performed with two models in which repulsive particles are enclosed inside a vesicle. The distribution of the particles and the effective bending coefficient and surface tension of the membrane are analyzed. The shape and internal structure of the vesicle containing the particles are investigated as the vesicle volume is decreased. It is revealed that the repulsive interaction between particles produces a layered structure and stiffens the membrane. When particles repulsively interact over a long range, the membrane takes on a dumbbell form.

Topology-optimized carpet cloaks based on a level-set boundary expression.

The concept of topology-optimized carpet cloaks is presented using level-set boundary expressions. Specifically, these carpet cloaks are designed with the idea of minimizing the value of an objective functional, which is here defined as the integrated intensity of the difference between the electric field reflected by a flat plane and that controlled by the carpet cloak. Made of dielectric material, our cloaks are designed to imitate reflections from a flat plane, and with some cloaks, the value of the objective functional falls below 0.12% of that for a bare bump on a flat plane. These optimal carpet cloaks spontaneously satisfy the time-reversal symmetry of the scattered field during the optimization process. The profiles associated with optimal configurations are controlled by adjusting a regularization parameter. With this approach, a variety of configurations with different structural characteristics can be obtained.

Topology-optimized multiple-disk resonators obtained using level set expression incorporating surface effects.

Topology-optimized designs of multiple-disk resonators are presented using level-set expression that incorporates surface effects. Effects from total internal reflection at the surfaces of the dielectric disks are precisely simulated by modeling clearly defined dielectric boundaries during topology optimization. The electric field intensity in optimal resonators increases to more than four and a half times the initial intensity in a resonant state, whereas in some cases the Q factor increases by three and a half times that for the initial state. Wavelength-scale link structures between neighboring disks improve the performance of the multiple-disk resonators.

[A case report of recurrent small bowel adenocarcinoma successfully treated with monoclonal antibody against EGFR and S-1].

A man in 30s was admitted to our hospital with a complaint of abdominal and back pain. Abdominal CT scan showed a large mass and double balloon endoscopy detected a tumor of the jejunum. The pathological diagnosis of biopsy samples was poorly differentiated adenocarcinoma. After radical resection, adjuvant chemotherapy with mFOLFOX6 was administered, however, a recurrent lesion developed. Although the lesion was successfully removed again, it did not react to the combination therapy with irinotecan and cisplatin. Because the tumor showed a high percentage of epidermal growth factor receptor (EGFR) expression and also had a wild-type KRAS status, a therapeutic strategy targeting EGFR was selected. The patient started on panitumumab associated with S-1 and obtained a complete response on CT 6 weeks later. Small bowel adenocarcinoma is an aggressive malignancy with a poor prognosis and little information about its definitive chemotherapy. Analysis of molecular characterization, an increase in reported experience, and prospective trials are needed to improve a prognosis.

Local-gauge finite-element method for electron waves in magnetic fields.

The finite-element method (FEM) has already been extended to analyze transport properties of electron waves of two-dimensional electron systems in magnetic fields. Although many researchers have created new formulations or improvements to this method, few have analyzed how this method is applied to realistic systems. The present paper suggests that conventional formulations of the FEM do not give accurate results for large systems or for strong magnetic fields; in addition, it suggests that the selected gauge significantly influences the numerical results. Furthermore, this paper proposes a conceptually different formulation of the FEM that solves the poor convergence problem. This formulation is simple: matrix elements are multiplied by the Peierls phase in the absence of a magnetic field. To show the advantages of this formulation, numerical examples are presented.

Study on transition from photonic-crystal laser to random laser.

The dependence of the lasing threshold on the amount of positional disorder in photonic crystal structures is newly studied by means of the finite element method, not of the finite difference time domain method usually used. A two-dimensional model of a photonic crystal consisting of dielectric cylinders arranged on a triangular lattice within a circular region is considered. The cylinders are assumed to be homogeneous and infinitely long. Positional disorder of the cylinders is introduced to the photonic crystals. Optically active medium is introduced to the interspace among the cylinders. The population inversion density of the optically active medium is modeled by the negative imaginary part of dielectric constant. The ratio between radiative power of electromagnetic field without amplification and that with amplification is computed as a function of the frequency and the imaginary part of the dielectric constant, and the threshold of the imaginary part, namely population inversion density for laser action is obtained. These analyses are carried out for various amounts of disorder. The variation of the lasing threshold from photonic-crystal laser to random laser is revealed by systematic computations with numerical method of reliable accuracy for the first time. Moreover, a novel phenomenon, that the lasing threshold have a minimum against the amount of disorder, is found. In order to investigate the properties of the lasing states within the circular system, the distributions of the electric field amplitudes of the states are also calculated.

Inducible nitric oxide synthase and survivin messenger RNA expression in hepatocellular carcinoma.

PURPOSE: Proliferative activity and suppression of apoptosis of cancer cells are important to tumor progression in hepatocellular carcinoma (HCC). Recently, the expressions of inducible nitric oxide synthase (iNOS) and survivin mRNA have been reported to correlate with suppression of apoptosis in some tumors. However, the clinical importance of expression of these genes in HCC progression remains unclear. In the present study, the correlation between the expression of iNOS and survivin mRNA and the occurrence of spontaneous apoptosis and proliferative activity of cancer cells and prognostic importance of expression of these genes in HCC were investigated. EXPERIMENTAL DESIGN: Tissues were obtained by surgical resection of livers from 61 patients with HCC and 8 without HCC. Expressions of iNOS and survivin mRNA were evaluated using the reverse transcription-PCR in 61 tumors, 61 adjacent histologically noncancerous livers, and 8 normal livers. Apoptotic cancer cells and the proliferative activity of cancer cells were detected by immunohistochemistry. RESULTS: iNOS mRNA expression was detected in 34 of 61 (55.7%) HCCs, 19 of 61 (31.1%) noncancerous liver tissues adjacent to carcinoma, and none of the 8 normal livers. In addition, survivin mRNA was detected in 19 of 61 (31.1%) HCCs, none of 61 noncancerous liver tissues, and none of the 8 normal livers. iNOS mRNA expression did not correlate with the proliferative activity of cancer cells or with the occurrence of apoptosis in HCCs. In contrast, survivin mRNA expression strongly correlated with a high proliferative activity of cancer cells and a low apoptotic index. Disease-specific survivals did not differ between patients with iNOS-positive or -negative HCCs. Although, the disease-specific survival of patients with survivin-positive HCCs was significantly poorer than that of patients with survivin-negative HCCs. CONCLUSIONS: These results indicate that iNOS may not correlate with cancer cell-proliferative activity or apoptosis; survivin, however, may not only suppress apoptosis but also accelerate cancer cell-proliferative activity and play an important role in tumor progression in HCC.

Quantitative analysis of heparanase messenger RNA expression in hepatocellular carcinoma.

BACKGROUND AND OBJECTIVES: In the process of tumor invasion, cancer cells secrete enzymes including heparanase that degrade extracellular matrices and basement membranes of blood vessels. In the present study, the clinical importance of enhanced expression of heparanase messenger RNA (mRNA) in hepatocellular carcinoma (HCC) was evaluated. METHODS: Fresh tumor and noncancerous liver tissue adjacent to a tumor were obtained from 50 patients with HCC immediately after hepatic resection. The expression levels of heparanase mRNA were analyzed quantitatively, using the real-time reverse transcriptase-polymerase chain reaction (RT-PCR) method, and were compared with clinicopathological findings. RESULTS: Relative heparanase mRNA expression level in HCC was significantly lower than that of noncancerous liver tissue (P < 0.001). Tumor heparanase expression did not correlate with tumor differentiation, tumor stage, or patient prognosis. CONCLUSIONS: Enhanced heparanase mRNA expression may not be a good biological marker in HCC. J. Surg. Oncol. 2002;81:148-154.

Beta-catenin and cyclin D1 expression in human hepatocellular carcinoma.

To understand the nature and roles of mutated beta-catenin in human hepatocellular carcinomas (HCCs), 57 cases of surgically resected HCCs were studied. DNAs extracted from each tumor were examined for somatic mutations of exon 3, and the protein expressions of beta-catenin, cyclin D1, and Ki-67 were observed by immunohistochemical staining. beta-catenin mutations in exon 3 were detected in 10 (17.5%) out of 57 HCCs, including nine missense mutations and one deletion mutation. All of the cases with gene alterations had the anti-HCV antibody, and tested negative for the HBs antigen in the sera. All of the mutations occurred at the serine/threonine phosphorylation sites of glycogen synthase kinase-3beta (GSK-3beta) or their neighboring residues. Significant correlation with intracellular expression (p=0.00055) was shown in the HCCs harboring beta-catenin mutations. The intracellular accumulation of beta-catenin showed significant correlation with the cyclin D1 expression (p=0.00858), and with a higher proliferation index (p=0.00072). In addition, the beta-catenin mutations showed significant association with the cyclin D1 expression (p=0.0424). These results suggest that accumulated beta-catenin proteins may bind to the lymphocyte enhancer binding factor-1 (LEF-1), form the beta-catenin/LEF-1 complex, and stimulate such promoters regulating the cell cycle as the cyclin D1 gene. This is the first report to demonstrate a significant correlation between beta-catenin and the cyclin D1 expression in human HCCs.

Expression of inducible nitric oxide synthase during cisplatin-based chemotherapy for gastric cancer.

BACKGROUND: Nitric oxide (NO) has been reported to protect cells from apoptosis during chemotherapy. In this study, the protective role of inducible nitric oxide synthase (iNOS) against cisplatin (CDDP)-induced apoptosis was evaluated in a cell line and in patients with gastric cancer. MATERIALS AND METHODS: MKN-45 cells were incubated with CDDP and the correlation between the occurrence of apoptotic cells (evaluated by flow cytometry) and the expression of iNOS messenger RNA (mRNA) in cells was analyzed. In 15 patients with advanced gastric cancer, CDDP-based preoperative chemotherapy was introduced. The expression levels of iNOS mRNA were compared between tumor samples before and after treatment with CDDP. Moreover, the iNOS protein expression and the percentage of apoptotic cancer cells (apoptotic index: AI) were analyzed immunohistochemically in 15 CDDP-treated tumors and in 50 untreated advanced gastric cancers. RESULTS: High AI was detected after 24 hours of treatment with high-dose CDDP in MKN-45, while the iNOS mRNA expression levels did not change before and after treatment. In 15 patients treated with CDDP, the percentage of iNOS mRNA-positive cases increased from 20% (pretreatment tumors) to 40% (resected tumors). However, the mean AI of iNOS-positive tumors was not different from that of iNOS-negative tumors. Also, in 50 untreated patients, iNOS protein expression did not correlate with the AIs of the tumors. CONCLUSION: Our results demonstrate that iNOS expression may not correlate with the occurrence of apoptosis during CDDP treatment in gastric cancer.