Publications by authors named "Masahiko Okamura"

Self-expandable metallic stent (SEMS) was introduced for the treatment of obstructive colorectal cancer (CRC) a few decades ago. However, its long-term outcomes remain controversial, especially for stage IV CRC. The aim of this study was to clarify the outcomes of SEMS as a "bridge to surgery" (BTS) for obstructive and symptomatic primary tumors in stage IV CRC by one-to-one propensity-score matching.

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Background: Acute cholecystitis is one of the most prevalent surgical abdominal conditions. The Tokyo Guidelines describe the management of acute cholecystitis and recommend bailout procedures for "difficult" cholecystitis cases. This study aimed to identify risk factors for conversion from laparoscopic cholecystectomy to bailout procedures in patients with acute cholecystitis.

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An 84-year-old woman had locally advanced sigmoid colon cancer that was unresectable because of deep invasion in the left pelvic wall. Transverse double-barrel colostomy was performed owing to stenosis in the sigmoid colon. The patient's performance status score was 2, and it was difficult to administer cytotoxic chemotherapy.

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A 77-year-old man was diagnosed with gastric cancer with synchronous single liver metastasis and portal vein thrombus. His HER2 immunohistochemistry tumor score was 3+; therefore, we administered trastuzumab plus capecitabine plus cisplatin. After 2 courses of chemotherapy, we observed disappearance of the portal vein thrombus and tumor reduction as a partial response, according to the RECIST guidelines.

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We established the optimal conditions for the induction of cell death by cisplatin (CDDP) and 5-fluorouracil (5-FU) in human oral squamous cell carcinoma (HSC-2, HSC-3, HSC-4) and human hepatocellular carcinoma (HepG2) cell lines. HSC-3 cells were the most sensitive to 48 hours' continuous treatment with CDDP, followed by HepG2, HSC-2 and HSC-4 cells. On the other hand, HSC-4 cells were the most sensitive to 48-hour continuous treatment with 5-FU, followed by HSC-2, HSC-3 and HepG2 cells.

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The possible apoptosis-inducing activity of several sequential treatments of cisplatin (CDDP) and 5-fluorouracil (5-FU) against the human oral squamous cell carcinoma HSC-2 cell line was investigated. The following three combination treatments (CT) were used: simultaneous treatment with CDDP and 5-FU (for 72 hours) (CT-1), CDDP treatment (24 hours) followed by 5-FU treatment (48 hours) (CT-2) and 5-FU treatment (24 hours) followed by CDDP treatment (48 hours) (CT-3). CT-1 produced the highest cytotoxicity, followed by CT-3 and CT-2.

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Three antitumor antibiotics, mitomycin C, bleomycin sulfate and peplomycin sulfate, were compared for their tumor-specific cytotoxicity, using human oral squamous cell lines (HSC-2, HSC-3, HSC-4, Ca9-22 and NA), human promyelocytic leukemic cell line HL-60 and human normal oral cell types (gingival fibroblast HGF, pulp cell HPC and periodontal ligament fibroblast HPLF). Among these three compounds, mitomycin C showed the highest tumor-specificity, due to its higher cytotoxic activity against human oral tumor cell lines than bleomycin and peplomycin. However, there was considerable variation of drug sensitivity among the six tumor cell lines.

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The sensitivity of human hepatoma (HepG2) and oral squamous cell carcinoma (HSC-2) cell lines against various apoptosis-inducing agents was compared. HepG2 cells were generally more resistant to an oxidant (H2O2), antioxidants (sodium ascorbate, gallic acid, epigallocatechin gallate) and anticancer drugs (doxorubicin, methotrexate, cisplatin (CDDP), etoposide, 5-fluoro-2,4(1H,3H)-pyrimidinedione (5-FU), peplomycin sulfate) as compared to HSC-2 cells. Lower concentrations of CDDP, but not other anticancer drugs, induced comparable cytostatic effects on both HSC-2 and HepG2 cells.

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We have recently found that sodium fluoride (NaF) induced apoptotic cell death in tumor cell lines. We investigated here whether 6 popular antitumor compounds modify the cytotoxic activity of NaF against human squamous cell carcinoma (HSC-2) and human promyelocytic leukemia (HL-60) cell lines. Cytotoxic concentrations of cisplatin, etoposide, doxorubicin or peplomycin (tentatively termed as Group I compounds), but not methotrexate and 5-FU (tentatively termed as Group II compounds), enhanced the cytotoxic activity of NaF.

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