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Biomedical subjects

N Yoshii

Publications and source records attributed to N Yoshii.

72 records · Page 4Linked to original sources
PubMedDate not supplied

Ca uptake and Ca releasing properties of the endoplasmic reticulum in rat peritoneal mast cells.

In order to study the characteristics of the intracellular Ca store of mast cells, organelles of rat peritoneal mast cells were fractionated. The binding of 45Ca was at its peak in the fractions where the highest activity of glucose-6-phosphatase, the marker enzyme for the endoplasmic reticulum (ER), was measured. The ER-rich fraction exhibited an ATP-dependent uptake of 45Ca and this uptake was inhibited by pretreatment with ATPase inhibitors such as LaCl3 or Na3VO4. When inositol 1,4,5-trisphosphate (IP3) was added to a medium containing the 45Ca-loaded ER fraction, it caused a dose-dependent release of 45Ca at concentrations higher than 0.5 microM, while inositol 1-monophosphate and inositol 1,4-bisphosphate were not effective even at higher concentrations. The results of a binding assay using 3H-labeled IP3 indicated that there exist two kinds of IP3 binding site in the ER: one is of high affinity but low capacity while the other is of low affinity and high capacity. IP3-induced 45Ca release was dose-dependently inhibited by pretreatment with c-AMP. The present study supports the assumption that the intracellular Ca store associated with histamine release from the mast cell is the ER.

Adenosine Triphosphate↗
PubMedDate not supplied

Role of endoplasmic reticulum, an intracellular Ca2+ store, in histamine release from rat peritoneal mast cell.

By means of the Ca-antimonate precipitation technique, it was revealed that Ca2+ accumulates in the endoplasmic reticulum (ER) of rat peritoneal mast cells. The ER of rat mast cells was isolated using Percoll density gradient centrifugation, and its characteristics were studied. Although the uptake of 45Ca into the ER was enhanced by adenosine 5'-triphosphate (ATP) at concentrations lower than 2 mM, at higher concentrations ATP induced 45Ca release from the ER, suggesting that bidirectional translocation of Ca2+ takes place in the ER membrane. When apyrase was added to the reaction mixture to decompose all ATP molecules, the amount of 45Ca in the ER was decreased, indicating that ATP is necessary to retain Ca2+ in the ER. Not only inositol 1,4,5-trisphosphate (IP3) but also guanosine 5'-triphosphate (GTP) was effective in releasing Ca2+ from the ER at concentrations higher than 2 microM, while guanosine 5'-[gamma-thio]-triphosphate (GTP-gamma S), a non-hydrolysable analogue of GTP, was not effective. This may indicate that a hydrolysis of GTP is necessary for Ca2+ release from the ER. Intracellular Ca2+ blockers such as 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) and dantrolene sodium were effective in inhibiting Ca2+ release from ER induced by IP3. The Ca2+ release due to IP3 was also inhibited by flunarizine, a Ca2+ channel blocker, and by oxatomide, an antiallergic drug. Since these two compounds are diphenylpiperazine derivatives, it is suggested that a diphenylpiperazine moiety may be effective in inhibiting Ca2+ release from the ER.

Adenosine Triphosphate↗
PubMedDate not supplied

Follow-up study of epileptic patients following forel-H-tomy.

Stereotactic Forel-H-Tomy has been performed in 20 cases of epilepsy refractory to medication of which 15 have been followed from 2 to 7 years. The outcome of operation in 7 cases is judged as 'markedly effective' or 'effective'. In 3 cases the operation was ineffective. Effectiveness was greater in bilateral operation. Improvement of EEG was indicated by disappearance or marked reduction of spikes (or sharp waves) or spike and wave complex. Grand mal seizures alone or cases of minor seizure alone have responded more favorably than other clinical types. Six cases demonstrated improvement of personality and emotions.

Adolescent↗
PubMedDate not supplied

Several clinical aspects of thalamic pulvinotomy.

Several clinical aspects of thalamic pulvinotomy were investigated. Influence of electrical stimulation of pulvinar on consciousness, speech, memory, evoked response, emotion, intelligence, character, ophthalmic and auditory examinations were studied during operation and compared between pre-, post, and during operation.

Adolescent↗