Biomedical subjects

Masaru Tanaka

Publications and source records attributed to Masaru Tanaka.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Study of blood compatibility with poly(2-methoxyethyl acrylate). Relationship between water structure and platelet compatibility in poly(2-methoxyethylacrylate-co-2-hydroxyethylmethacrylate).

Previously, we reported that poly(2-methoxyethylacrylate) (PMEA) showed excellent blood compatibility and implied that the water structure in PMEA contributed to the blood compatibility. In this study, the relationship between the water structure and the blood compatibility is clarified by studying the influence of the monomer composition of poly(MEA-co-HEMA) on the water structure and the blood compatibility of the copolymers. The water in the polymer was classified into three types: free water, freezing bound water, and nonfreezing water. The polymers with 0-30 mol % of HEMA content had a significant amount of freezing bound water, and the amount decreases greatly when the composition of HEMA exceeded 30 mol %. On the other hand, the amount of other water increased simply with an increase of HEMA content. The evaluation of the platelet compatibility of poly(MEA-co-HEMA) revealed that the adhesion number and the morphological change of platelet on the copolymer surface were least when the HEMA content was 0-20 mol %. These two results strongly suggest that the freezing bound water relates to the platelet compatibility of the polymers.

Acrylates↗

PubMedDate not supplied

The effects of jatrophane derivatives on the reversion of MDR1- and MRP-mediated multidrug resistance in the MDA-MB-231 (HTB-26) cell line.

Multidrug resistance (MDR) of cancer cells can be the result of a variety of mechanisms that are not completely understood. One of the most significant among them concerns altered membrane transport in tumor cells, often referred to as typical or classic MDR. This mechanism is related to the overexpression of a variety of proteins, that belong to the super family of ABC transporters. The aim or this study was to look for new effective modulators of MDR1 and multidrug resistance-associated protein (MRP) transporters. Ten diterpenes based on the jatrophane skeleton, including rearranged polycyclic derivatives, were studied on the MDA-MB-231 (HTB-26) human breast cancer cell line. The majority of those compounds were able to strongly enhance the rhodamine 123 accumulation of the human MDR1 gene transfected mouse lymphoma cell line, as previously described. In the present study, the MDR reversal of the same jatrophanes on MDR1- and MRP- mediated resistance of human breast cancer cells is reported. These cells simultaneously express MDR1 and MRP proteins when identified by monoclonal antibodies. However, in a functional assay, where rhodamine 123 accumulation was measured and verapamil was the traditional positive control, only MRP was active, while MDR1 was inactive. Carboxyfluorescein served as a substrate for MRP-mediated drug efflux, and indomethacine was the positive control used as an inhibitor of MRP in the flow cytometric experiments. The effectivity of various jatrophanes was different on the carboxyfluorescein efflux inhibition of the human breast cancer cells. These results may have importance in the planning of a new type of combination chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

Reversal of multidrug resistance of cancer cells in vitro: modification of drug resistance by selected carotenoids.

The development of multidrug resistance (MDR) causes difficulties in the chemotherapy of of human cancer. Investigation of the possibility of reversal of MDR has been greatly aided by the use of cell lines with acquired resitance to anticancer agents in vitro or transfected with the mdrl gene. The aim of this study was to examine new perspectives of chemotherapy focused on natural, carotenoid compounds, in connection with the modification of MDR. The function of the MDR protein was examined via the R123 drug accumulation of both cell lines in the presence of carotenoids. The fluorescence of the cell population was measured by flow cytometry. The most effective resistance modifiers Monoepoxy-beta-carotene, (SS, 8S)-capsochrome, (8'S) Luteoxanthin, (9Z)-Violaxanthin, (9Z)-Zeaxanthin, (13Z)-Zeaxanthin were assayed for their antiproliferative effects in combination with the anti-cancer drug epirubicin. (13Z)-Zeaxanthin was able to enhance the antiproliferative effect on human mdrl gene transfected mouse lymphoma and anthracycline resistant human breast cancer cell line MCF7. (8'S)-luteoxanthin, (5S, 8S)-capsochrome and (9Z)-zeaxanthin treatment revealed synergism with epirubicin on resistant mouse lymphoma. The enhanced antiproliferative activity of epirubicin combinated with (9Z)-Violaxanthin was more significant on MCF7 cells resistant to anthracycline.

ATP Binding Cassette Transporter, Subfamily B, Mem↗