Since oxygen, especially its metabolic products, hydrogen peroxide and superoxide anion, are cytotoxic, we intended to culture cells under reduced oxygen concentrations in order to examine some biological effects of oxygen on cells. For this purpose, a new type of nitrogen gas generator was constructed and connected to a CO_2 incubator to reduce oxygen concentration less than 20%. The mechanistic principle of the generator is to remove the oxygen from the incoming air using an adsorption column with carbon molecular sieves (CMS) and to obtain almost 100% pure nitrogen gas. By using this generator plating efficiency and growth rate of cells were tested under humidified gas conditions of 1% O_2,5% CO_2,and 94% N_2. As a result, most of the cell lines examined showed higher plating efficiency and growth rate compared with under conventional culture conditions of a humidified atmosphere of 95% air and 5% CO_2. The use of this new type of the nitrogen gas generator has the following merits : 1) no need to use N_2 gas cylinder, 2) no need to daily check of the cylinder, 3) no occasional exchange of the empty cylyinder, 4) no troublesome labor for the exchange of the cylinder, 5) more economical than the N_2 gas cylinder, 6) a high possibility of culturing cells which cannot grow under the present conventional culture conditions.
In order to introduce the computer aided engineering (CAE) technology to the design of the infant incubator, we developed an interface software system to optimize the internal environment of an infant incubator, based upon series of our previous computational fluid mechanical studies. Developed system could semiautomatically generate a computational fluid mechanical model of an incubator using the coordinate values of important structures in the incubator from a CAD (computer aided design) data file. It can also set the condition of the computation and the obtained computational results agreed well with the correspondent experimental results.
Methyl methacrylate polymer (PMMA) is widely used as the dental plate. After fabrication of PMMA, methacrylate monomer, benzoylperoxide, N, N'-dimethyl ρ-toluidine used for starting reagents were remained. These were toxic and the residue of these compounds as well as time course of elution were already reported. In addition to these compounds, newly found toxic compounds with hydrophilic characteristics were identified and determined the amount eluted in human saliva, so analytical procedure of these compounds using high performance liquid chromatography-mass spectrometry combined with ultrafiltration is presented.