Search PubMed⌕ Search

Biomedical subjects

S Koga

Publications and source records attributed to S Koga.

At least 523 records · Page 29Linked to original sources
PubMed1966

Physical properties of cell water in partially dried Saccharomyces cerevisiae.

The equilibrium vapor pressure, the heat of vaporization, the dielectric increment, and the NMR spectra of partially dried cells were studied in Saccharomyces cerevisiae with water contents varying in the range from 25 to 0.8%. The comparative study of those physical properties suggests that physical states of the microbe can be classified into four regions in accordance with the states of the cell water: the solution region, the gel region, the mobile adsorption region, and the localized water region. Much difference in the physiological properties is found between the cells in the solution region and those in the gel region, whereas the pattern changes in physical properties take place when the cells in the gel region are dried to a further extent into the mobile or the localized region. The various modes in the molecular motion of the cell water reflected in those physical properties of the cell seem to give some insight into the biological functions of the molecule in the native as well as the dried states of the cell.

Electrophysiology↗
PubMed1965

Dielectric behavior of yeast cells treated with HgC-12 and cetyl trimethyl ammonium bromide.

The change in dielectric properties caused by the destruction of the transport barrier of yeast cells has been investigated. Dielectric measurements were made over the frequency range of 1 kc to 2 Mc by using "leaky" yeast cells prepared by treatments with HgCl(2) or CTAB (cetyl trimethyl ammonium bromide). The Hg-treated cells were observed to give smaller dielectric constants and lower critical frequencies as compared with that of the intact cells, while the CTAB-treated cells gave no clear-cut dielectric dispersion. These observations are interpreted on the basis of Maxwell-Wagner's theory as indicating the changes in the intracellular conductivity, the membrane capacitance and the membrane conductance.

Anti-Infective Agents↗
PubMedDate not supplied

Measurement of rate constants for quenching singlet oxygen with a Cypridina luciferin analog (2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo [1,2-a]pyrazin-3-one) and sodium azide.

The rate constants for [1O2] [MCLA] and [1O2] [NaN3] were measured by quenching the near-infrared emission (1 delta g----3 sigma g) in steady state with MCLA and NaN3, respectively. 1O2 was constantly generated by energy transfer to O2 from Ar laser-excited Rose Bengal. The Stern-Volmer plots yielded the second-order rate constants of 2.94 x 10(9) M-1 S-1 and 3.83 x 10(8) M-1 S-1 for quenching 1O2 with MCLA and NaN3 in water at pH 5.4, respectively. The 1O2 + MCLA reaction emitted light with maximum at 465 nm at pD 4.5 identical to the O(2-) + MCLA reaction.

Azides↗
PubMedDate not supplied

Plasma lipoproteins and apoproteins in primary biliary cirrhosis.

To elucidate abnormalities in lipid metabolism in patients with primary biliary cirrhosis (PBC), plasma lipoproteins and apoproteins were analyzed in 10 such patients. Lipoprotein X was present in sera from five of the patients. Another abnormal lipoprotein of slow alpha-mobility on agarose gel electrophoresis was observed in sera of eight of the patients. The slow alpha-lipoprotein was distributed in the range of densities between low density and high density lipoproteins and was rich in apoprotein E. This abnormal lipoprotein of PBC was observed in those in Stages II and III but not in those in Stage I. The amounts of slow alpha-lipoprotein correlated to the levels of serum apoprotein E and to total cholesterol. Determination of apoprotein concentrations in serum of PBC patients revealed increases of apoproteins E and C-II and a decrease of apoprotein A-II. In conclusion, lipoprotein abnormalities in PBC patients were characterized by increased levels of apoprotein E and appearance of an abnormal lipoprotein of slow alpha-mobility in addition to well-known lipoprotein X.

Adult↗