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Biomedical subjects

M Kawase

Publications and source records attributed to M Kawase.

At least 181 records · Page 10Linked to original sources
PubMed1984

Biphasic release of thyrotropin in response to thyrotropin-releasing hormone (TRH) from rat anterior pituitary cells in vitro: possible dependence on protein synthesis.

Mechanisms related to the biphasic release of TSH were studied using primary cultured cells of the rat anterior pituitary gland on micro-carrier beads in a superfusion system. Release of TSH in response to continuous exposure to TRH exhibited a biphasic pattern; the first phase was characterized by a rapid, transient and high-rate release (phase I) and the second phase by a chronic and low-rate release (phase II). The shift of the release from phase I to phase II occurred by treatment with TRH at concentrations from submaximal to maximal. When the Ca2+ concentration in the medium was decreased, the phase I release was partially inhibited, while the phase II release was completely inhibited, suggesting a difference between the mechanisms in phase I and phase II release. The phase I release was not suppressed by cycloheximide. This protein synthesis-independent release of phase I seemed to be linked to the intracellular releasable pool of TSH. The phase II release was suppressed by the presence of a protein synthesis inhibitor. After the phase II release was suppressed by cycloheximide, the magnitude of phase I release in response to re-exposure to TRH markedly decreased. The decreased phase I release in response to TRH was observed with the cells which were previously stimulated by high K+ instead of TRH, suggesting that the decrease in the response of phase I reflects the depletion of a releasable pool of TSH rather than homologous desensitization of thyrotrophs with TRH. These results suggest that the phase I release of TSH depends on a portion of the previously prepared-releasable pool while phase II release depends on previously prepared plus newly prepared pools of TSH. Replenishment of the releasable TSH pool was considered to involve protein synthesis.

Animals↗
PubMed1983

High-performance liquid chromatographic method for the determination of plasma allantoin.

A new method has been devised for the determination of nanomole levels of allantoin in human plasma. Allantoin was converted into xanthylallantoin, which was chromatographed on a reversed-phase silica gel using a mixture of acetonitrile-water (27:73) as mobile phase. The eluted compound was measured using an ultraviolet detector. The detection limit of the assay for plasma was about 100 ng/ml. This method was applied successfully to the determination of allantoin in human plasma after oral administration of 100 mg of aldioxa.

Adult↗
PubMed1982

Mode of action of 3-substituted propylamine cytotoxicity in culture cells.

Cytotoxic effects on MDBK cells of various 3-substituted propylamines, including spermine and spermidine, were tested in culture in the presence of calf serum, and the possible mode of action was studied from the viewpoint of oxidative deamination leading to acrolein formation. The compounds were roughly classified in two groups with IC50 values of 0.1 and 0.4 mM under the conditions used. Phenyl derivatives of 3-substituted propylamines, 3-benzylaminopropylamine, and polyamines were included in the first group with IC50 values of 0.1 mM, and acrolein was liberated from these compounds after incubation with bovine plasma amine oxidase. Alkyl derivatives of 3-substituted propylamines (with IC50 values of 0.4 mM), on the other hand, were unable to release acrolein after the oxidative deamination, which was further confirmed by a lack of liberation of acrolein from the authentic 3-butoxypropanal. These observations indicated that both the acrolein originating from the 3-substituted propanals, and the propanal as such, were possibly involved in manifestation of the cytotoxicity of the 3-substituted propylamines. Thus, spermine and spermidine may exert their cytotoxic effects on the cells in vitro by a combination of two mechanisms involving acrolein and oxidized polyamines.

1-Propanol↗
PubMed1982

Mitochondrial damage in galactosamine-induced liver intoxication in rats.

Mitochondria isolated from livers of rats which received D-galactosamine (375 mg/kg body wt., four times) demonstrated a marked decrease in respiratory control ratios, the ADP/O ratios, and state 3 respiration rates and an increase in state 4 respiration rates. The aberration was profound with site I being altered prior to sites II and III. Quantitation of phospholipids revealed a reduction of total phospholipids per mg protein with decreases in phosphatidylcholine and phosphatidylethanolamine contents. Caldiolipin was the only phospholipid which remained unaltered. Fatty acid composition was altered in these phospholipids; caldiolipin was altered most severely, showing reductions in linoleic and arachidonic acids, and an elevation in saturated fatty acids and in some other small components of fatty acids. In phosphatidylethanolamine, palmitic acid decreased, whereas stearic and docosahexenoic acids increased. These changes were smaller in phosphatidylcholine fatty acids. These mitochondria were also characterized by an altered composition in high molecular weight polypeptide components. By experiments with normal mitochondria in vitro, galactosamine, but not other aminohexoses, was proved to be an uncoupling agent of the oxidative phosphorylation system. Electron microscopic observation demonstrated that both in vivo and in vitro treatments with galactosamine induced marked disorganization of mitochondrial structures. These results suggest that mitochondrial damage is also included in galactosamine-induced hepatic lesion.

Animals↗
PubMed1981

[Aneurysm of sinus of Valsalva ruptured into the interventricular septum: a case report (author's transl)].

A 48-year-old male with a history of progressive atrioventricular conduction disturbance and a peculiar diastolic regurgitant murmur was reported. The echocardiographic examination and cineangiography disclosed an aneurysm of the right coronary sinus of Valsalva ruptured into the interventricular septum, which bulged into the left ventricular outflow tract in diastole and moved toward the septum in systole. The intracardiac phonocardiogram revealed that an unperforated sac in the interventricular septum, protruded into the left ventricular outflow tract, caused an unusual regurgitant murmur. The patient underwent successful surgical repair of the perforated orifice.

Aortic Rupture↗
PubMed1980

Improved gas chromatographic method of determining diclofenac in plasma.

Diclofenac was converted into either its methyl or ethyl ester in methanol or ethanol containing 0.1% or 0.5% sulfuric acid, respectively. The ester was extracted and subjected to gas--liquid chromatography with electron-capture detection. The esterification resulted in an increased sensitivity of the gas chromatographic detection, three times better than that previously reported for the formation of indolone ring in trifluoroethanol containing 0.5% sulfuric acid.

Chromatography, Gas↗
PubMed1979

[A study on the physiological basis of training effect--with special reference to myoglobin. I. Isolation and properties of myoglobin from dog skeletal muscle (author's transl)].

Myoglobin (Mb) was isolated from canine skeletal muscle by a novel heat denaturation-gel filtration-ion exchange chromatography procedure. The purified major Mb was homogeneous by gel electrophoretic and ultracentrifugal analysis, and the sedimentation coefficient at infinite dilution (S degrees 20, w) was 1.9 S. The molecular weight by sedimentation equilibrium was 1.72 X 10(4) and was essentially identical with the values by the iron analysis (1.80 X 10(4) and the amino acid composition (1.78 X 10(4). The spectroscopic properties of deoxy-, oxy-, carbonmonoxy- and met-derivatives of the Mb were determined in ultraviolet, Soret and visible regions. The pK' of acid-alkaline transition of the met-Mb was estimated as 8.80+/-0.04 (25 degrees) from the pH-dependent spectral change. The oxygen equilibrium studies revealed complete absence of such allosteric properties as heme-heme interaction, anion effect and the Bohr effect which were always present in normal mammalian hemoglobins. Oxygen tension for the half-oxygenation was 0.48 mmHg (20 degrees) and its temperature-dependent change gave the delta H degrees of -15.7 Kcal/mole.

Amino Acids↗