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Biomedical subjects

K Terayama

Publications and source records attributed to K Terayama.

At least 91 records · Page 5Linked to original sources
PubMed1979

Sulfhydryl groups of pyocin R1. Morphology and activity modified with sulfhydryl reagents.

Electron microscopic observation of pyocin R1 with the negative staining technique demonstrated that pyocin R1 retained its phage tail-like shape of an extended sheath even when it was inactivated by treatment with p-chloromercuribenzoic acid (PCMB) or 4-(p-sulfophenylazo)-2-mercuriphenol (SAMP). Thus it was shown that the contraction and extension of the sheath does not occur reversibly on the modification of sulfhydryl groups accompanying the change of activity. The activity lost under these conditions was restored to the original level by treatment with 2-mercaptoethanol (2-ME). Numbers of sulfhydryl groups in the pyocin R1 particle were determined to be 208 mol and 152 mol per mol (11.8 x 10(6) daltons) by spectrophotometric titration with SAMP and by membrane-filter assay with radioactive PCMB, respectively. Most of these cysteine residues appeared to be localized in the substructure other than the sheath and core. It was also shown that all of these sulfhydryl groups were not necessary for expression of its activity but a part of them were essential for adsorption to the sensitive cells.

Bacteriocins↗
PubMed1978

Toxicity of heavy metals and insecticides on slime mold Physarum polycephalum.

Toxicity of heavy metals and insecticides on the slime mold Physarum polycephalum was investigated in order to examine and estimate with ease the toxicity of environmental and occupational contaminants and also to study the effects of various agents on the cell membrane. Changes in survival time and in membrane potential of the slime mold were measured using a double chamber method. The results obtained suggest that their toxicity for the slime mold is accompanied by some change in the cell membrane, and that studies on toxicity for various chemical substances in the slime mold can be used as a screening method.

Animals↗
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↗
PubMed1976

Knee forces during the activity of getting out of a chair with and without the aid of arms.

This is a preliminary study of the knee forces during the activity of getting out of a chair with and without the aid of arms. The equipment limited the study to the phase of the activity where no contact occurred between the subject and the chair seat. The model of the knee considered was two-dimensional, and quasi-static. Analysis showed that the forces acting in both compartments of the knee were comparable with those occurring during other non-strenuous activities such as level walking. It was also shown that the use of arms to aid rising from a chair causes considerable reduction in both joint and muscle forces.

Arm↗
PubMed1975

Threshold phenomena in chemoreception and taxis in slime mold Physarum polycephalum.

The plasmodium of Physarum polycephalum reacts to various kinds of chemicals substances and moves towards or away from them. Threshold concentration of recognition of chemicals was examined in terms of membrane potential and of the averaged motive force of tactic movement by using a double-chamber method, i.e., a single plasmodium was placed between two compartments through a narrow ditch, and differences in membrane potential and in pressure between two compartments were measured. Results are summarized as follows: (a) By increasing the concentration of various substances in one compartment, the membrane potential started to change at a certain threshold concentration, C-th, for each chemical. Chemotactic movement of the plasmodium took place at the same threshold concentration. These results held both for attractants (glucose, galactose, phosphates, pyrophosphates, ATP, c-AMP, etc) and for repellents (various inorganic salts, sucrose, fructose, etc.). (b) The threshold concentration, Cth, for inorganic salts decreased remarkably with increase of the valences of cations, zeta, and was proportional to Z-6, I.E., THE Shultze-Hardy rule known in the field of colloid chemistry was found to be applicable. (c) The plasmodium distinguished the species of monovalent cations in the following order: H(Li(K(Na(Rb(Cs(NH-4 Plots of log Cth against the lyotropic number of anion fell on different straight lines for each monovalent cation species. (d) Plots of log Cth, against the reciprocal of the absolute tempe lines were almost the same and gave a value of 12 kcal/mol for the enthalpy change. These results suggest that the recognition of chemical substances appears as the result of a structural change of the membrane at the threshold point, and that the change in membrane structure is transmitted simultaneously to the motile system of the plasmodium.

Adenosine Triphosphate↗