Biomedical subjects

Norifumi Ohashi

Publications and source records attributed to Norifumi Ohashi.

7 recordsLinked to original sources

PubMed2006

In vitro chemosensitivity test to predict chemosensitivity for paclitaxel, using human gastric carcinoma tissues.

BACKGROUND: Therapy guided by chemotherapy sensitivity and resistance assays may lead to rational treatment decisions. Paclitaxel, one of several new drugs for gastric carcinoma, has not been extensively evaluated by in vitro chemosensitivity tests. METHODS: Chemosensitivity testing by histoculture drug response assay (HDRA) was performed with fresh specimens of primary tumor from 113 patients with gastric carcinoma. The test was performed in medium containing paclitaxel at three different concentrations for the initial 45 samples. Correlations between the results of chemosensitivity testing, determined at the optimal concentration, and the patients' clinicopathologic factors and outcome were then assessed for all patients. RESULTS: By analyzing the initial 45 samples, 10 microg/ml was considered the optimal concentration of paclitaxel for this test. HDRA was successfully performed for 100 of 113 samples and chemosensitivity, calculated as the percentage of optical density of a tumor treated with anticancer drugs in relation to the optical density of the tumor cultured in the medium only, was distributed widely at this concentration. No significant correlation was observed between chemosensitivity and age, sex, clinical stage, histopathologic type, and outcome of patients with gastric carcinoma. CONCLUSION: A histoculture drug response assay can now be performed to predict the chemosensitivity of paclitaxel at the concentration found in the current study. The accuracy of the assay to actually predict survival needs to be validated by a prospective clinical trial involving patients who have received paclitaxel in the postoperative adjuvant setting.

Adult↗

PubMed2006

A carbohydrate recognition-based drug delivery and controlled release system using intraperitoneal macrophages as a cellular vehicle.

The lymphoid tissue in the omentum, at the so-called milky spots, is known as an initial place for disseminated cancer cells to develop into solid tumors. In the present study, i.p. macrophages significantly took up oligomannose-coated liposomes (OMLs) that were injected into the peritoneal cavity, and then gradually accumulated in the omentum and the other lymphoid tissues within 24 hours of i.p. injection of OMLs. When 5-fluorouracil (5-FU) was encapsulated in the OMLs, >60% of administered 5-FU accumulated in the omentum. Treatment of macrophages at 39 degrees C for 30 minutes led to the release of 5-FU from the macrophages, suggesting that controlled release from macrophages could be achieved by mild hyperthermia. We encased magnetic nanoparticles, which are known to convert electromagnetic energy to heat in the OMLs to achieve in vivo hyperthermia at the site. Using this system in a mouse i.p. metastasis model, we successfully controlled tumor development by coadministration of OML-encased 5-FU and OML-encased magnetic nanoparticles, followed by treatment with an alternating magnetic field. No apparent reduction was seen in tumor growth with the administration of OML-encased magnetic nanoparticles or OML-encased 5-FU alone. Thus, we have established the use of i.p. macrophages as a novel drug delivery system for the control of cancer metastatic to milky spots.

Animals↗

PubMed2006

Biological significance of isolated tumor cells and micrometastasis in lymph nodes evaluated using a green fluorescent protein-tagged human gastric cancer cell line.

PURPOSE: The biological significance of isolated tumor cells and micrometastasis in lymph node defined by the International Union against Cancer remains essentially unknown because of the lack of appropriate animal models. In the present study, we developed a lymph node micrometastasis model featuring a human gastric cancer cell line tagged with green fluorescent protein gene (GCIY-EGFP), which allows visualization of even isolated tumor cells in the development of metastasis without histologic procedure. Using this model, we investigated the effect of surgery and chemotherapy on the growth of early-phase metastasis formation in the lymph nodes. EXPERIMENTAL DESIGN: The time course of spontaneous inguinal lymph node metastasis after s.c. inoculation of GCIY-EGFP cells into nude mice was examined with fluorescence dissecting microscopy. Then, the effects of surgical removal of the primary tumor with or without anti-asialo GM1 treatment or postoperative chemotherapy on the growth of isolated tumor cells and micrometastasis in the lymph nodes were examined. RESULTS: GCIY-EGFP cells were found to metastasize spontaneously to the inguinal lymph nodes to form isolated tumor cells, micrometastasis, and, finally, develop macroscopic metastasis at 1 to 2, 3 to 5, and 5 weeks postinjection, respectively. When the primary tumors were removed within 2 weeks of inoculation, isolated tumor cells, but not micrometastasis, in the lymph nodes regressed by 4 weeks after surgery in all the mice examined (five of five). This spontaneous regression of isolated tumor cells was completely reversed by anti-asialo GM1 treatment, which could deplete natural killer cells effectively in nude mice. Chemotherapy following resection of the primary tumor at an early stage partially eliminated the remaining micrometastasis in the lymph nodes. CONCLUSIONS: These results suggest that isolated tumor cells in the regional lymph nodes regressed by removal of the primary tumor mainly via natural killer cell-mediated antitumor activity and that micrometastasis in the lymph nodes could be effectively eliminated by the postoperative chemotherapy.

Animals↗

PubMed2005

Prognostic significance of intraperitoneal cancer cells in gastric carcinoma: analysis of real time reverse transcriptase-polymerase chain reaction after 5 years of followup.

BACKGROUND: The presence of gastric cancer cells in the peritoneal cavity detected by cytologic examination is an important prognostic factor. A reverse transcriptase-polymerase chain reaction (RT-PCR) technique amplifying carcinoembryonic antigen mRNA was recently introduced to detect these cells more sensitively. STUDY DESIGN: Five-year followup was completed for 284 gastric carcinoma patients who underwent CEA RT-PCR testing. Analyses to assess the accuracy and prognostic value of this procedure were performed, along with univariate and multivariable analyses to evaluate RT-PCR as a technique with peritoneal carcinomatosis and cancer death as the outcomes variables. RESULTS: CEA mRNA levels exceeded the cutoff value defining a positive result in 9.5%, 29%, 66%, and 81% of patients with pT1, pT2, pT3, and pT4 stage disease, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value for peritoneal carcinomatosis within 5 years of surgery were 88.5%, 81.6%, 64.5%, and 94.9%, respectively. Multivariable analysis revealed that a positive CEA mRNA result was an independent risk factor for cancer death (hazard ratio 2.82, 95% CI 1.17 -3.07) among 274 patients (10 patients with no record of nodal status were excluded from the analysis) and for peritoneal carcinomatosis (hazard ratio 1.57, 95% CI 1.07-2.29) among 242 patients who had no peritoneal deposits at operation. CONCLUSIONS: CEA RT-PCR is useful as a prognostic marker for increased risk of cancer death and peritoneal carcinomatosis, and might be useful in the clinical setting for selecting patients for various adjuvant treatments.

Aged↗

PubMed2005

Laparoscopy-assisted distal gastrectomy with systemic lymph node dissection: a phase II study following the learning curve.

BACKGROUND AND OBJECTIVES: A preliminary study on the use of laparoscopy-assisted approach to treat gastric carcinoma resulted in higher morbidity. STUDY DESIGN: A prospective phase II study of laparoscopy-assisted distal gastrectomy (LADG) was performed for patients with preoperative diagnosis of T1 N0 stage cancer located in the lower or middle-third stomach. Bleeding amount, operating time, mortality, morbidity, and the number of lymph node retrieval were recorded and compared with the preliminary series reported previously by the same authors. RESULTS: Between 2000 and 2002, 47 patients were accrued. The mean blood loss and postoperative hospital stay were significantly decreased compared with the previous series, whereas the operating time was not. There were no in-hospital deaths, with the incidence of anastomotic leakage significantly decreased. All patients remain disease-free to date. CONCLUSIONS: LADG can be performed safely and morbidity, no longer, is a drawback by experienced hands that have reached plateau of the learning curve, although it remains a time-consuming procedure. Its application to gastric cancer surgery is feasible for early stage cancer, and its applicability to the treatment of T2 stage cancer will be the next issue to be explored.

Adult↗

PubMed2005

Efficacy of intraperitoneal chemotherapy with paclitaxel targeting peritoneal micrometastasis as revealed by GFP-tagged human gastric cancer cell lines in nude mice.

To explore the effect of chemotherapy against peritoneal micrometastases, we used in vivo models of peritoneal micrometastasis featuring three human gastric cancer cell lines tagged with the green fluorescence protein gene. With a highly metastatic cell line, GCIY-EGFP, the survival rate of mice treated with weekly intraperitoneal paclitaxel starting one day following inoculation was significantly higher than those of control mice or mice given the same treatment starting on day eight. Intravenous paclitaxel exhibited no significant survival benefit regardless of the treatment schedule. Pharmacokinetic analysis revealed that the concentration of paclitaxel in the metastatic nodules treated with intraperitoneal administration was 2-3-fold higher than those treated with intravenous paclitaxel, provided the treatment was given on day one. Even greater responses were observed with less aggressive MKN28-EGFP and MKN45-EGFP cell lines, whose peritoneal metastases resolved completely due to early intraperitoneal treatment in 13 of the 14 mice tested. These results indicate that intraperitoneal paclitaxel is effective against peritoneal metastasis in early phase.

Animals↗

PubMedDate not supplied

Combination of oral fluoropyrimidine and docetaxel: reappraisal of synergistic effect against gastric carcinoma xenografts.

BACKGROUND: The synergistic antitumor effect of a combination of docetaxel and capecitabine is reported to be attributable to docetaxel-mediated up-regulation of thymidine phosphorylase (dThdPase). MATERIALS AND METHODS: Intravenous docetaxel (15 mg/kg) was given to nude mice bearing xenografts of the gastric cancer cell lines MKN45 and MKN28. Mice were sacrificed on days 7, 10 and 22 and tumor samples were taken to measure the activities of thymidylate synthase, dihydropyrimidine dehydrogenase, dThdPase and orotate phosphoribosyltransferase. The efficacy of capecitabine or S-1, alone and in combination with docetaxel, was then evaluated in vivo. Docetaxel was administered intravenously on days 8 and 22 at 15 mg/kg, while capecitabine (269 mg/kg) or S-1 (7.5 mg/kg) were administered orally 5 times a week for 4 weeks. RESULTS: Tumor regression was observed only for a combination of capecitabine and docetaxel against MKN28, while additive growth inhibition was obtained by the combination of docetaxel and both S-1 and capecitabine on MKN45 tumor xenografts. Induction of dThdPase activity was observed only for MKN45. The activity of no other enzyme was significantly affected following administration of docetaxel. CONCLUSION: The combination of oral fluoropyrimidine and docetaxel showed augmented antitumor activity, but this may be attributed to mechanisms other than changes in 5-fluorouracil-metabolizing enzymes.

Administration, Oral↗