Cancer Cell Analyses at the Single Cell-Level Using Electroactive Microwell Array Device

Circulating tumor cells (CTCs), shed from primary tumors and disseminated into peripheral blood, are playing a major role in metastasis. Even after isolation of CTCs from blood, the target cells are mixed with a population of other cell types. Here, we propose a new method for analyses of cell mixture at the single-cell level using a microfluidic device that contains arrayed electroactive microwells. Dielectrophoretic (DEP) force, induced by the electrodes patterned on the bottom surface of the microwells, allows efficient trapping and stable positioning of single cells for high-throughput biochemical analyses. We demonstrated that various on-chip analyses including immunostaining, viability/apoptosis assay and fluorescent in situ hybridization (FISH) at the single-cell level could be conducted just by applying specific reagents for each assay. Our simple method should greatly help discrimination and analysis of rare cancer cells among a population of blood cells.     

Use of an activated carbon column for the synthesis of disaccharides by use of a reversed hydrolysis activity of β-galactosidase

Summary An activated carbon column was utilized for the synthesis of disaccharides by use of a reversed hydrolysis activity of an immobilized -galactosidase column in order to shift the equilibrium to the direction of condensation. The yields of lactulose and allo-lactulose from galactose and fructose, and N-acetyl lactosamine and N-acetyl allolactosamine from galactose and N-acetyl glucosamine, were 11.3% and 10.0%, respectively.     

Active site organization of bacterial type I fatty acid synthetase

Four kinds of active sites of bacterial fatty acid synthetase were mapped on distinct regions within a subunit. Active sites were specifically labeled with radioactive substrates and active-site-directed inhibitors. Labeled enzymes were cleaved with proteases, and the fragments thus produced were identified with respect to specific labels by SDS-polyacrylamide gel electrophoresis and a fluorographic technique. The linear alignment of such fragments in the original subunit was established and when the results were combined with those of our previous work, five active sites were located in three regions as follows. Starting from the N-terminal of the subunit, we located acetyl, malonyl and palmitoyl transferases in the first region, the acyl carrier site in the second region (Morishima & Ikai (1985) Biochim. Biophys. Acta 832, 297-307), and beta-ketoacyl synthetase in the third region. The observed order of active sites of bacterial fatty acid synthetase can be correlated with that of the yeast enzyme, which has two kinds of subunits.     

Decreased intracellular free magnesium in erythrocytes of spontaneously hypertensive rats

Using 31p-NMR (the phosphorus nuclear magnetic resonance) spectroscopy, we measured intracellular free Mg levels in the erythrocytes of untreated (n = 7) and diltiazem-treated spontaneously hypertensive rats (SHR) (n = 8), and compared them with age-matched Wistar-Kyoto rats (WKY) (n = 10). The intracellular free Mg levels were significantly (p less than 0.01) decreased in untreated SHR compared with those in control WKY. A successful antihypertensive treatment with diltiazem increased the intracellular free Mg levels compared with untreated SHR (p less than 0.05). Furthermore, an inverse correlation was observed between intracellular free Mg levels and blood pressure levels in all groups (r = -0.48, p less than 0.01, n = 25). These observations suggest that abnormalities of intracellular Mg metabolism may be, in part, related to the development or the maintenance of hypertension in SHR.     

Hydrophobicity of Fusobacterium necrophorum biovars A and B

Abstract Biovar A strains of Fusobacterium necrophorum exhibited high hydrophobicity when examined by the method of Rosenberg et al. Biovar B strains showed a lower cell surface hydrophobicity than biovar A strains. Biovar B strains were divided into 2 groups according to their hydrophobic activity. The strains of biovar A and the first group of biovar B were increasingly removed from aqueous phase to octane phase by increasing the volume of octane, but the turbidity of the second group of biovar B was not significantly affected. The hydrophobicity of biovar A strains decreased on heating at 60 and 100°C for 30 min.     

Surface Charge Density Estimation of Vigna mungo Protoplasts Using a Fluorescent Dye, 9-Aminoacridine

We showed that the surface charge density of protoplasts canbe estimated by the 9-aminoacridine method. The estimated surfacecharge density of the protoplasts isolated from elongating regionsof Vigna mungo root was – 39 ? 8 mC/m². The negative surfacecharge density increased when protoplasts were treated withglutaraldehyde or when EDTA was added to the protoplast suspensionmedium. These results support the validity of our estimationof the surface charge density of protoplasts by the 9-aminoacridinemethod. The concentration of amino groups at the surface ofthe protoplasts was estimated to be 34 mC/m². (Received June 19, 1987; Accepted April 11, 1988)