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Biomedical subjects

K Tsuda

Publications and source records attributed to K Tsuda.

At least 433 records · Page 24Linked to original sources
PubMed1975

I-cell disease. Report of three cases.

Clinical, radiological, histochemical, ultrastructural, and biochemical studies were conducted on three cases of I-cell disease. I-cell disease can be readily distinguished from Hurler syndrome (mucopolysaccharidosis I) by the presence of hypertrophic gums, vacuolated lymphocytes in peripheral blood, and a normal level of urinary mucopolysaccharides. Accumulation of proteoglycans was more prominent in the inclusion bodies of I-cell chondrocytes in comparison to cultured fibroblasts, which contained a large amount of glycolipids and a small amount of proteoglycans. An autosomal recessive mode of inheritance was suggested in two of the cases.

Abnormalities, Multiple↗
PubMed1974

Electrical excitability in the egg cell membrane of the tunicate.

1. With the purpose of studying the differentiation of an excitable membrane, the electrical properties of the tunicate egg, a mosaic egg, was examined by intracellular recording techniques. The species used were Halocynthia aurantium Pallas and H. roretzi Drashe.2. The membrane in the matured but unfertilized egg, the fertilized but uncleaved egg, and the cleaved egg showed the resting potential of +5 to -15 mV.3. Hyperpolarization beyond -60 mV elicited a regenerative response in the form of an ;off response' with a critical membrane potential of about -40 mV and with an over-shoot of 10-20 mV above the original resting potential.4. The removal of Na from standard artificial sea water and the enhancement of Ca in Na-free ASW revealed both Na and Ca components in the ;off response'.5. In both std ASW and Na-free ASW the I-V relation of the egg cell membrane showed marked non-linearity, forming an S-shaped curve. In the range of positive membrane potential, the embryonic membrane showed a moderate outward-going rectification; in the potential range below -60 mV there was a considerable inward-going rectification. So far as examined, the shape of the I-V relation was affected only by changes of K concentration in the ASW, but not by those of other cations.6. Specific capacity of the egg cell membrane was 1.0 muF/cm(2). The specific slope resistance below -70 mV was 130 kOmega cm(2) for the unicellular egg and 50 kOmega cm(2) for the two cell embryo.

Action Potentials↗
PubMed1974

Analysis of non-linearity observed in the current-voltage relation of the tunicate embryo.

1. In the gastrula of the tunicate (Halocynthia aurantium) the resting potential of the embryonic membrane was about -70 mV in both std ASW and Na-free ASW.2. The potential responses to depolarizing current in the early gastrula embryo showed distinct potential jumps from about -50 to about +40 mV during the application of current and from about 0 to resting level after its cessation thus forming a plateau at about 0 mV. Those jumps were not altered significantly by the removal of both Na and Ca ions from ASW except for the duration of the plateau after the cessation of current.3. Blastomeres in an embryo were tightly coupled with each other electrotonically at the blastula and gastrula stages. The fact that the coupling ratio was nearly 1.0 made it reasonable to treat an embryo as one cell as far as electrical properties are concerned.4. The I-V relation of the embryonic membrane consisted of an inward rectifying region, outward rectifying region and transitional zone between the two, resulting in a S-shaped curve as in the egg cell membrane. But in the gastrula embryo, the transitional zone actually included the discontinuous part of the I-V curve (from about -50 to about +40 mV) due to the potential jump.5. The ionic current (I(i)) during the potential jump in Na-free ASW was estimated from the slope of the potential response based on the assumption of constant capacitance during the membrane potential changes. The calculated I(i)-V curve complemented the interrupted I-V curve smoothly and showed the existence of a negative resistance region from about -50 to about 0 mV in the steady-state I-V relation.6. The steady-state I-V relation was altered significantly by changing the K concentration in ASW, and the existence of the negative resistance can be reasonably explained by the marked inward-going rectification or anomalous rectification of K conductance.7. The replacement of K with Rb in ASW produced the marked suppression of the inward-going rectification of the embryonic membrane.

Animals↗
PubMed1972

Calcium and sodium contributions to regenerative responses in the embryonic excitable cell membrane.

Ionic dependence of regenerative responses of the embryonic cell mnembrane has been studied successively at each stage of development from the unfertilized egg to the differentiated striated muscle in the tadpole larva of the tunicate. The unfertilized egg cell itself showed a type of regenerative response dependent on both sodium and calcium ions, while the spike potentials exclusively dependent on calcium ions were elicited in the differentiated muscle cell.

Action Potentials↗