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Biomedical subjects

I Karube

Publications and source records attributed to I Karube.

At least 109 records · Page 6Linked to original sources
PubMed1987

Tumor cell detection method using complement-mediated cytolytic reaction and imaging sensor system.

A novel tumor-detection system consisting of complement-mediated cytolytic reaction and an image processing system was developed for the simple and rapid determination of tumor cells. The present system consists of a CCD image sensor, image memory board, personal computer, and microscope. When monoclonal antibody 3C4, which is specific to the guinea pig hepatoma L-10, was added to cell suspension, only L-10 cytolysis occurred. Cytolysis caused a decrease in brightness of the cells observed by phase-contrast microscopy. The phase contrast image of the cells before cytolysis was converted to a digitalized signal and stored in computer memory. After cytolysis, a brightness threshold above that of lysed cells was subtracted from the digitalized signal and compared to the signal stored before reaction. L-10 cells in mixed cell suspension were determined specifically by the system. Measurement time was only 2 sec and overall time, including reaction time, was approximately 30 min. Since this method does not require a cell washing process, automation of the whole system is possible.

Animals↗
PubMed1987

Basic studies of hydrogen evolution by Escherichia coli containing a cloned Citrobacter freundii hydrogenase gene.

Citrobacter freundii genes that complemented Escherichia coli hyd-(hydrogenase activity) mutation were cloned in plasmids pCBH4 (6.2 kb) and pCBH6(5.7 kb). Hydrogen evolution by the transformant E. coli HK-8(pCBH4 or pCBH6) was investigated. The optimum culture temperature of recombinant E. coli cells for hydrogen evolution from glucose was in the neighborhood of 18 degrees C. The recombinant E. coli cells cultured at this condition showed a several-fold increase of hydrogen evolution, as compared with that of the wild-type cells. The plasmid-retention stability of this recombinant E. coli was extremely high, especially plasmid pCBH4, which was completely retained during 2 wk without any restriction. Hydrogen production by immobilized recombinant E. coli was then investigated using cells cultured at 18 degrees C. The hydrogen evolution rate from glucose and Lennox-broth were about twofold higher than that of E. coli C600, and this high hydrogen evolution rate was maintained for more than 1 mo.

Citrobacter↗
PubMed1987

Rapid detection of leukemia cells by use of a complement-mediated cytolytic reaction and an imaging sensor system.

We describe a system for detection of leukemia cells involving complement-mediated cytotoxic reaction and an image processing system, consisting of a charge-coupled-device image sensor, an image memory board, a personal computer, and a phase-contrast microscope. Then added to a cell suspension, monoclonal antibody specific to the fetal thymus antigen-1 of the mouse leukemia GRSL cell produced cytolysis of only GRSL cells. This cytolysis decreased the brightness of the cells observed by phase-contrast microscopy. The remaining brightness was subtracted from that of the phase-contrast image of the cells before cytolysis, which had been converted to a digital signal and stored in computer memory. Measurement time is 2 s. The time course for complete GRSL cytolysis, as measured with this system, is 12 min; overall measurement time, including reaction time, is approximately 15 min. GRSL cells in a suspension of mixed cells were determined specifically by the system.

Cell Count↗
PubMed1986

Electrical stimulation of hybridoma cells producing monoclonal antibody to cAMP.

Electrical stimulation was applied to hybridoma cells in order to activate metabolic activities and increase the monoclonal antibody production. Hybridoma cells that produce monoclonal antibody to adenosine 3':5'-cyclic monophosphate were placed on a transparent glass electrode immersed in medium and subjected to electric pulses (pulse shape, alternating rectangular; field strength, 4 X 10(3) V X m-1; frequency, 5 kHz; pulse mode, 0.5 min application and 4.5 min pause). After 48 h of incubation, the concentration of lactic acid in the medium reached 8.4 mM, approx. 30% higher than that obtained without electric stimulation. Similarly, cell growth rate was promoted by the electric stimulation, reaching a maximum stimulation after 40 h. When the hybridoma was cultured for 48 h with electrical stimulation, the antibody concentration in the medium reached 22.3 microgram X ml-1, approx. 10% higher than the control, with a concomitant 16% increase in cell concentration. Longer periods of electric pulse application, however, caused an inhibitory effect on the hybridoma growth. The most probable cause of the inhibition are reactive oxygen species such as superoxide and hydrogen peroxide, which are inevitably generated by electrolysis. The presence of superoxide dismutase (EC 1.15.1.1) reduced the inhibitory effects. In conclusion, metabolic activities including monoclonal antibody production were activated by the electrical stimulation.

Animals↗
PubMed1986

Novel immunosensors.

The development of practical immunosensors is an important topic for biosensor research. Recently the authors have demonstrated novel immunosensors called, respectively, the reactor-type enzyme immunosensor, the potentiometric sensing system for pathogenic microbes, the piezo-immunosensor, the pulse immunoassay, the bio-image sensor and the photofluctuation immunosensor. These six types of immunosensors based on novel principles are described.

Antibodies↗
PubMed1984

New cell fusion method using polymer membrane.

A porous polymer membrane of nitrocellulose or tetrafluoroethylene (TFE) was employed for fusion of Saccharomyces cerevisiae (AH22 and D13-1A) protoplasts. Protoplasts were adsorbed on the membrane with slight suction. Some part of the protoplasts was trapped in pores of the membrane as observed by electron microscopy. The membrane retaining protoplasts was placed on a selective medium. Several colonies appeared on the medium after 5-7 days incubation at 30 degrees C. The fusion of the two strains was ascertained by DNA content and genetic markers. Fusion frequency was 1.2 X 10(-6) in the case of the TFE membrane.

Cell Fusion↗
PubMed1983

Cloning and expression of the hydrogenase gene from Clostridium butyricum in Escherichia coli.

Hydrogenase gene from Clostridium butyricum was cloned in Escherichia coli HK16 (Hyd-) using pBR322 and PstI. The plasmid, pCBH1, containing hydrogenase gene was 7.3 MDa and pCBH1 had 5 PstI-DNA fragments (3.9, 2.6, 0.7, 0.03-0.04, less than 0.02 MDa, respectively). The hydrogenase activity of HK16 (pCBH1) was about 3.1-3.5-times as high as those of the present strains, such as C.butyricum and E.coli C600 (Hyd+).

Cloning, Molecular↗