Biomedical subjects

M Tanifuji

Publications and source records attributed to M Tanifuji.

24 records · Page 2Linked to original sources

PubMed1990

[A case report of postoperative thyroid crisis accompanied with struma ovarii].

A 39-year-old female without any specific past history was scheduled to receive an operation for myoma uteri and ovarian cyst. She was premedicated with atropine. Anesthesia was induced with thiopental and was maintained with nitrous oxide and enflurane. Tachycardia shortly after premedication with atropine and remarkable sweat during the operation were observed. On the 1st postoperative day an outbreak of thyroid crisis as well tachycardia of 180.min-1 and fever (39.3 degrees C) were observed. Such outbreak of thyroid crisis indicated that the patient had been suffering from Grave disease. Pathological diagnosis of extirpated ovarian cyst was struma ovarii. It is, however, still uncertain whether struma ovarii induced thyroid crisis in this case. It might be concluded that screening of hyperthyroidism at preoperative rounds is essential for prevention of thyroid crisis.

Adult↗

PubMed1989

Further characterization of the cation channel of a yeast vacuolar membrane in a planar lipid bilayer.

A voltage-dependent and Ca2(+)-activated cation channel recently found in the vacuolar membrane of the yeast Saccharomyces cerevisiae was incorporated into planar lipid bilayers and further characterized in macroscopic and single channel levels. Single channel conductances for various cations were in the order: NH4+ greater than K+ greater than Rb+ greater than Cs+ greater than Na+ greater than Li+, and were nearly consistent with the order of permeability ratio estimated from reversal potentials determined by macroscopic measurement. Up to 6 mM of Ca2+ added to the cis (cytoplasmic) side opened the channel, but higher concentrations closed the channel without affecting the single channel conductance. Ba2+ closed the channel without affecting the single channel conductance. Ba2+ closed the channel from the cis side. In addition to the above channel, a small cation-selective channel of about 40 pS was found.

Anions↗

PubMed1988

Gating behaviors of a voltage-dependent and Ca2+-activated cation channel of yeast vacuolar membrane incorporated into planar lipid bilayer.

A voltage-dependent and Ca2+-activated cation channel found in the vacuolar membrane of the yeast, Saccharomyces cerevisiae, was incorporated into planar lipid bilayer and its gating characteristics were studied at the macroscopic and single-channel levels. The open-channel probability at steady state, which was estimated by the macroscopic current measurement, gave a maximum value at -10 mV and decreased in a graded fashion as the voltage became more positive or more negative. The steady-state voltage dependence was explained by assuming two independent gates, which had different rate constants and opposite voltage dependence. The fast-responding gate opened when the voltage of the cis side (the side to which the vesicles were added) was made more negative and the slow-responding gate behaved in the opposite direction. Relatively high concentrations of Ca2+, about 1 mM, were required on the cis side for opening the slow gate in a voltage-dependent manner. DIDS increased the open-channel probability of the fast gate when added to the cis side, but was ineffective on the slow gate.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1987

Vacuolar ion channel of the yeast, Saccharomyces cerevisiae.

Ionic flux is most likely to regulate the chemiosmotic potential differences across vacuolysosomal membranes in animal, plant, and fungal cells. We found a membrane potential-dependent cation channel in yeast vacuolar membrane and characterized its several features by an electrophysiological method using artificial planar bilayer membranes incorporated with isolated yeast vacuolar membrane vesicles. This ion channel conducts K+ (single channel conductance, 435 pS in 0.3 M KCl) and several other monovalent cations (Cs+, Na+, and Li+) with broad selectivity, but does not conduct Cl-. The opening of this channel is regulated by the membrane potential and the presence of calcium ion on the cytoplasmic face. These characteristics suggested that the vacuolar cation channel functions as one of essential components for formation and regulation of the chemical and electrical potential differences across the vacuolar membrane.

Calcium↗

PubMed1987

An anion channel of sarcoplasmic reticulum incorporated into planar lipid bilayers: single-channel behavior and conductance properties.

An anion channel of sarcoplasmic reticulum vesicle has been incorporated into planar lipid bilayers by means of a fusion method and its basic properties were investigated. Analysis of fusion processes suggested that one SR vesicle contained approximately one anion channel. The conductance of this channel has several substates and shows a flickering behavior. The occupation probability of each substate was voltage dependent, which induced an inward rectification of macroscopic currents. Further, the anion channel was found to have the following properties. (1) The single-channel conductance is about 200 pS at 100 mM Cl-. (2) The channel does not select among monovalent anions but SO2-4 hardly permeates through the channel. (3) SO2-4 added to the cis side (the side to which SR vesicles were added) inhibits Cl- current competitively in a voltage-dependent manner. (4) An analysis of this voltage dependence suggests that the binding site of SO2-4 is located at about 36% of the way across the channel from the cis entrance.

Animals↗

PubMed1984

Study of intravenous hyperalimentation: effect of selected amino acids on the stability of intravenous fat emulsions.

In an attempt to resolve the conflicts relevant to intravenous fat emulsion compatibility two amino acids, L-valine and L-histidine monohydrochloride monohydrate, were chosen as intravenous additives, and these substances were investigated as to whether they could induce significant changes in the physicochemical properties of an intravenous soybean oil emulsion. The stability of the fat emulsion was evaluated in terms of gross visual observation, particle size distribution, surface tension, pH, and the zeta potential. It was found that (a) no significant difference was produced on the particle size distribution up to 7 d after admixing, (b) the mean diameter of oil globules was approximately 0.21-0.24 micron, and (c) the fat emulsion was sufficiently stable, with a zeta potential ranging between -30 and -60 mV. The relationship of the isoelectric point (pI) of the amino acids and the pH of the buffer solutions was determined to be one of the most important factors in the stability of the fat emulsion.

Amino Acids↗