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K Masamoto

Publications and source records attributed to K Masamoto.

11 recordsLinked to original sources
PubMed1979

Effect of surface potential on the intramembrane electrical field measured with carotenoid spectral shift in chromatophores from Rhodopseudomonas sphaeroides.

Changes in the surface potential, the electrical potential difference between the membrane surface and the bulk aqueous phase were measured with the carotenoid spectral shift which indicates the change of electrical field in the membrane. Chromatophores were prepared from a non-sulfur purple bacterium, Rhodopseudomonas sphaeroides, in a low-salt buffer. Surface potential was changed by addition of salt or by pH jump as predicted by the Gouy-Chapman diffuse double layer theory. When a salf was added at neutral pH, the shift of carotenoid spectrum to shorter wavelength, corresponding to an increase in electrical potential at the outside surface, was observed. The salts of divalent cations (MgSO4, MgCl-2, CaCl2) were effective at concentrations lower than those of monovalent cation salts (NACl, KCl, Na2SO4) by a factor of about 50. Among the salts of monoor divalent cation used, little ionic species-dependent difference was observed in the low-concentration range except that due to the valence of cations. The pH dependence of the salt-induced carotenoid change was explained in terms of the change in surface charge density, which was about 0 at pH 5--5.5 and had negative values at higher pH values. The dependence of the pH jump-induced absorbance change on the salt concentration was also consistent with the change in the charge density. The surface potential change by the salt addition, which was calibrated by H+ diffusion potential, was about 90 mV at the maximum. From the difference between the effective concentrations with salts of mono- and divalent cations at pH 7.8, the surface charge density of (-1.9 +/- 0.5) . 10(-3) elementary charge per A2, and the surface potential of about -100 mV in the presence of about 0.1 mM divalent cation of 5 mM monovalent cation were calculated.

Bacterial Chromatophores↗
PubMed1979

Relation of pancreatic duct hyperplasia to carcinoma.

In order to find a relationship between ductal hyperplasia and carcinoma of the pancreas, histological and histochemical examinations were made on pancreatic specimens of 1,174 autopsy patients with special attention to the age incidence of the former. Ductal hyperplasia was divided into 3 types; nonpapillary, papillary, and atypical hyperplasia. All three types of hyperplasia and ductal carcinoma showed a similar tinctorial property in mucous histochemistry. In general, atypical hyperplasia was seen in the pancreas having papillary hyperplasia which was found in the pancreas associated with nonpapillary hyperplasia. All three types of hyperplasia were apparently more frequent in cancerous pancreases than in non-cancerous ones. They were also more common in the head of the pancreas than in the body and tail. Age incidence also suggests a sequential change from nonpapillary hyperplasia through papillary and atypical ones to carcinoma.

Adolescent↗
PubMed1978

Gas chromatography of 5-hydroxy-3-methylindole in human urine.

Electron capture gas chromatography was used to estimate the urinary 5-hydroxy-3-methylindole in epileptic patients and normal controls. The urine was filtered, concentrated in vacuo, extracted into benzene-ethanol and passed through a silica gel column. The dried eluate was dissolved in acetonitrile, tri-fluoroacetylated and estimated by gas chromatography as di-trifluoroacetylated 5-hydroxy-3-methylindole. This structure was confirmed by gas chromatography-mass spectrometry. 5-Hydroxy-3-methylindole was excreted at high concentrations in some epileptics and at low concentrations in normal control subjects.

Adolescent↗
PubMed1977

H+ translocation in lysozyme-treated cells of the blue-green alga Plectonema boryanum. Difference between isotonically and hypotonically treated preparations and effects of divalent cations.

Lysozyme-treated cells of a blue-green alga, Plectonema boryanum, had an internal pH of 7.3+/-0.2 under isotonic and hypotonic conditions. This value was similar to that of untreated cells. The CCCP-induced biphasic H+ change seen in the isotonic cells was not observed in the hypotonically treated cells. The biphasic time course remained in the hypotonic preparation if CaCl2 or MgCl2 was added prior to the osmotic shock. It is suggested that the cells have two compartments of H+ concentration. The outer region may be more acidic than the inner region. A light-induced H+ efflux was observed under isotonic conditions and an influx of H+ under hypotonic conditions. The H+ influx was not observed when lysozyme-treated cells were incubated with CaCl2 or MgCl2 prior to the hypotonic treatment. Two types of effects of divalent cations, one on the rigidity of the outer membrane and another on the permeability characteristics of the inner photosynthetic membrane, are indicated. Rearrangement of the photosynthetic membranes and an apparent inversion of the H+ pump by hypotonic shock are also suggested.

Biological Transport, Active↗
PubMed1977

Estimation of internal pH in cells of blue-green algae in the dark and under illumination.

Carbonylcyanide m-chlorophenylhydrazone (CCCP) or nigericin induced translocation of H+ In the dark across the cell membrane of blue-green algae Plectonema boryanum and Anacystis nidulans. The direction of the H+ flux depended on the pH of the suspending medium. At acidic pH, an influx of H+ and at alkaline pH an efflux of H+ were observed. It is suggested that the influx takes place at pH'S higher than the "internal" pH and the efflux at pH's lower than that. The internal pH was estimated to be 7.4+/-0.2 for Plectonema boryanum and 7.5+/-0.1 for Anacystis nidulans. Similar H+ changes due to CCP were observed under illumination, where the light induced efflux of H+ was limited by the counter-flux of cations. The internal pH of cells in the light, estimated from the pH-dependent reversion in the rate of the H+ change, was about 8.5.

Biological Transport, Active↗