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Biomedical subjects

K Kurihara

Publications and source records attributed to K Kurihara.

At least 19 recordsLinked to original sources
PubMed1979

Selective modification of positive chemotaxis in the true slime mold Physarum polycephalum by ethylenediaminetetraacetic acid treatment.

The plasmodium of the true slime mold Physarum polycephalum was treated with EDTA or EGTA and the effect of the treatment on the chemotactic response was examined by measuring the chemotactic motive force with the double-chamber method. The results obtained were as follows: (1) The treatment of the plasmodium with 5 mM EDTA (pH 7.0, 20 min) did not give any significant effect on the protoplasmic streaming or motility. (2) The plasmodium treated with EDTA exhibited no chemotactic response to non-electrolyte attractants (D-glucose, D-galactose, D-mannose, and maltose) and negative chemotaxis to electrolyte attractants (cyclic AMP and NaH2PO4). (3) The EDTA treatment gave no effect on the chemotactic response to repellents (D-fructose, NaCl, CaCl2, MgCl2). (4) The EDTA-treated plasmodium exhibited changes in the membrane potential in response to both attractants and repellents as similar to the untreated plasmodium. (5) The treatment of the plasmodium with 5 mM EGTA (pH 7.0, 20 min) gave results similar to those obtained with the EDTA treatment. The results obtained suggested that EDTA (or EGTA) treatment did not affect the receptor sites but modified the transduction mechanism from reception into tactic movement.

Chemotaxis↗
PubMed1979

Photoinduced charge separation in liposomes containing chlorophyll a. I. Photoreduction of copper(II) by potassium ascorbate through liposome bilayer containing purified chlorophyll a.

Photosensitivity of dispersion of phosphatidylcholine bilayer liposomes containing purified chlorophyll alpha was examined. The reduction of Cu(II) in the solution outside liposomes was observed upon illumination with visible light under anaerobic condition by means of ESR. The rate of photoreduction was significantly increased by a reductant, potassium ascorbate, localized in the solution of the opposite side of the membrane. The aciton spectrum of the reduction agreed with the absorption spectrum of chlorphyll a in the dispersion. The amount of bleach chlorophyll a was negligible compared with that of reduced (Cu(II). These facts lead to the conclusion that the potoinduced redox reactions at both the membrane-solution interfaces are coupled with each other through the bilayer of each liposome. Kinetic analysis of the reactions based on a possible reaction scheme was carried out and some of the kinetic parameters were determined.

Anaerobiosis↗
PubMed1979

Gustatory responses of eel palatine receptors to amino acids and carboxylic acids.

The gustatory receptors of the eel palate were found to be extremely sensitive to amino acids and carboxylic acids. The results obtained are as follows: (a) 11 amino acids which are among naturally occurring amino acids elicited responses in the palatine nerve, but 9 amino acids did not elicit a response even at a high concentration. The effect of D-amino acids was always much less than that of their corresponding L-isomers. There was no appreciable difference in the effectiveness of an alpha-amino acid (alpha-alanine) and beta-amino acid (beta-alanine). (b) The threshold concentrations of the most potent amino acids (arginine, glycine) were between 10(-8) and 10(-9) M. A linear relation between the magnitude of the response and log stimulus concentration held for a wide concentration range for all the amino acids examined. (c) The palatine receptors responded sensitively to various carboxylic acid solutions whose pH was adjusted to neutral. The threshold concentrations varied between 10(-4) and 10(-7) M. The magnitude of the response at 10(-2) M increased with an increase of carbon chain length. (d) The extent of cross-adaptation was examined with various combinations of amino acids. A variety of the response patterns showing complete cross-adaptation, no cross-adaptation, or synergetic interaction was observed. The synergetic interaction was also observed when one amino acid below its threshold concentration was added to the other amino acid below its threshold concentration was added to the other amino acid. No cross-adaptation was observed between amino acids and fatty acids. (e) The treatment of the palate with papain led to loss of the responses to arginine, glycine, and histidine without affecting those to proline and acetic acid. The treatment with pronase E eliminated selectively the response to proline. The possibility that the eel gustatory receptors are responsible for sensing food at a distance was discussed.

Adaptation, Physiological↗
PubMed1979

A study on operative findings and pathogenic factors in ulnar neuropathy at the elbow.

A study was made of operative findings obtained in 44 cases of ulnar nerve neuropathy at the elbow in an attempt to help elucidate the pathogenetic factors for the condition. Distinction must be made between Lig. epitrochleo-anconeum or a ligament-like thickening at the same site and the tendinous arch of M. flexor carpi ulnaris. These 2 sites constitute the entrapment points for the condition. A thick tendinous arch, Lig. epitrochleo-anconeum of M. anconeus epitrochlearis deters the ulnar nerve from being mobile, thereby contributing to the development of neuropathy with trauma acting as a precipitating factor. Dislocation of the ulnar nerve cannot be considered a factor of major etiologic significance. An important part is played by the tendinous arch in the pathogenesis of neuropathy, regardless of whether it is in association with ganglion, osteochondromatosis or osteoarthritis. In surgery for ulnar neuropathy decompression of the nerve is of primary necessity. Division of the tendinous arch is mandatory. Medial epicondylectomy may be added as required.

Adolescent↗
PubMed1978

Role of membrane-bound calcium in taste reception of the frog.

1. The frog gustatory responses to various salt stimuli and distilled water were greatly enhanced after the tongue was treated with an alkaline solution containing salts of low concentration. The incubation of the alkali-treated tongue in solution of pH 6.0 containing Ca2+ restored reversibly the behaviour of the gustatory receptor to that before the treatment, while Mg2+ had no ability to do this. 2. The responses to salt stimuli and distilled water were greatly decreased after the tongue was incubated in solutions of pH 5.3 containing Ca2+. 3. On piece of tongue incubated in a solution of pH 5.3 containing 45Ca released a larger amount of 45Ca by the alkali treatment than another piece incubated in pH 7.0. It was concluded that removal of Ca2+ from the gustatory receptor membrane by the alkali treatment led to enhancement of the responses and binding of extra Ca2+ to the membrane by the incubation in acidic CaCl2 solution led to suppression of the responses. We emphasized that a conformational change of the receptor domains plays an important role in the transduction process of the gustatory response.

Action Potentials↗
PubMed1978

Breeding of cynomolgus monkeys through successive generations by indoor cage system.

Vital statistics on the breeding through successive generations were presented for the cynomolgus monkey colony of NIH, Tokyo. The results of this retrospective survey clearly demonstrated the third (F2) and the fourth (F3) generations could be bred and reared successfully by the indoor caged-breeding system in which either individual timed-mating or group mating procedure was adopted. Several important and difficult problems involved in the production of successive generations of the cynomolgus monkey by our breeding system were discussed from the standpoint of laboratory animal science.

Age Factors↗
PubMed1977

Effect of sugars on salt reception in true slime mold Physarum polycephalum. Physicochemical interpretation of interaction between salt and sugar receptions.

Interaction between salt and sugar receptions in plasmodium of Physarum polycephalum was studied by using double-chamber method. Effect of sugars on salt reception was evaluated by measuring membrane potential and the motive force of tactic movement of the slime mold, where salt concentration in one compartment was increased successively with a fixed sugar concentration. Results are summarized as follows: (1) The presence of D-glucose, D-mannose, D-maltose, or sucrose in medium led to increase of the threshold concentration Cth, for salts (chlorides and nitrates of Li, Na, K), whereas D-ribose decreased the threshold for salt reception. D-galactose showed no appreciable effect on Cth of every salt species examined. No change in Cth for salt reception was observed until concentration of sugars exceeded their respective thresholds. (2) Double logarithmic plots of Cth for salts against sugar concentration followed different straight lines for different cations, whose slopes being closely correlated with the effects of lyotropic number of anions in the absence of sugars. (3) Plots of log Cth against the reciprocal of the absolute temperature, 1/T, gave linear relations, and the slopes of the straight line became small with increase of sugar concentration above their respective thresholds. Experimental results obtained here suggest that the structure of water at the interface of cell membrane plays an indispensable role in the interaction between salt and sugar receptions.

Anions↗
PubMed1977

Selective electrode for dibenzyl dimethyl ammonium cation as indicator of the membrane potential in biological systems.

The electrode sensitive to dibenzyl dimethyl ammonium (DDA+), which is considered to be an indicator of the membrane potential, was constructed by using tetraphenyl borone (TPB-) embedded in dichloroethane. Rapid and Nernstian responses were exhibited against DDA+ solutions ranging between 10(-2) and 3 - 10(-6) M in concentration. High selectivity for DDA+ was observed in the presence of various inorganis salts, ADP, ATP, oxidizable substrates and sugars. The electrode developed here was used to measure the DDA+ uptake in Streptococcus faecalis and the results agreed with those reported by Harold, F.M. and Papineau, D. ((1972) J. Membrane Biol. 8, 27-44 and 45-62). While they determined the DDA+ concentration in the medium by measuring the absorbance of the filtrate treated with the ion-exchangers, the electrode can measure directly the DDA+ concentration in the bacterial suspension without any any pretreatment. It was also shown that the electrode can measure the DDA+ uptake in mitochondria during energization.

Animals↗
PubMed1976

Change in zeta potential and membrane potential of slime mold Physarum polycephalum in response to chemical stimuli.

Electrophoretic study of microplasmodia of the true slime mold Physarum polycephalum was carried out in the presence of various concentrations of inorganic salts, nucleotides and sugars, and the zeta potential at the surface of the plasmodia was determined from the electrophoretic mobilities. The membrane potential of the plasmodia was also measured under the same external conditions. It was shown that changes in the membrane potential induced by the chemical stimuli agreed approximately with those induced in the zeta potential in all cases examined. These results suggested that the phase boundary potential at the membrane-solution interface is mainly responsible for the membrane potential in the chemoreception of the slime mold.

Adenosine Triphosphate↗
PubMed1976

Phasic and tonic components of gustatory response in the frog.

Characteristics of phasic and tonic responses of the frog glossopharyngeal nerve to various salts were examined under a variety of conditions. The results obtained are summarized as follows: 1) The salt concentration of adapting solutions affected greatly the phasic component of the responses to NaCl, KCl, MgCl2, and CaCl2, whereas the tonic component was independent of the adapting condition. 2) Either the phasic or tonic component was preferentially suppressed under appropriate conditions. 3) An abrupt rise of temperature of stimulating solution produced a phasic response. Magnitude of the phasic response induced by a rise of temperature was a function of both species and concentration of salts in the stimulating solution. 4) Binding of Hg2+ to the receptor and elimination of the bound Hg2+ by mercaptoethanol gave similar large phasic response. A slow elimination of the bound Hg2+ led to no response. It was concluded that a phasic response appears only when environments such as salt concentration or temperature are changing and that its magnitude is related to the rate of changes, whereas a tonic response represents information of the receptor membrane in an equilibrium state. Discussion on the obtained results was made under an assumption that the phasic response is attributed to a dynamic conformational change of the receptor membrane.

Adaptation, Physiological↗