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Biomedical subjects

S Takemori

Publications and source records attributed to S Takemori.

At least 109 records · Page 6Linked to original sources
PubMed1983

Partial amino acid sequences of two mitochondrial and two microsomal cytochrome P-450's from adrenal cortex.

Partial amino acid sequences of two mitochondrial cytochrome P-450's, P-450 (SCC) and P-450 (11 beta), and two microsomal cytochrome P-450's, P-450 (C-21), and P-450 (17 alpha, Lyase), from adrenal cortex were analyzed and compared. Mitochondrial P-450's and microsomal P-450's were different in the amino acid sequences at their NH2-terminals. The sequences of microsomal P-450's started from terminal methionine and were highly hydrophobic, whereas those of mitochondrial P-450's lacked NH2-terminal methionine and were not hydrophobic. These findings strongly suggest that the NH2-terminal portions of newly synthesized P-450's determine their intracellular localization to different cell organelles.

Adrenal Cortex↗
PubMed1982

Effect of spin state on reduction of cytochrome P-450 (P-450C21) from bovine adrenocortical microsomes.

The effect of spin state on cytochrome P-450 reduction was studied with a reconstituted system consisting of P-450C21 and NADPH-cytochrome P-450 reductase (NADPH:ferricytochrome oxidoreductase, EC 1.6.2.4) purified from bovine adrenocortical microsomes. The absolute high spin contents of substrate-free, progesterone-bound and 17 alpha-hydroxyprogesterone-bound P-450C21 were estimated from the analysis of thermally induced difference spectra to be 25, 78 and 94% at 25 degrees C, respectively, in 50 mM potassium phosphate buffer (pH 7.2) containing 20% glycerol, 0.1 mM EDTA and 0.5% Emulgen 913. The effect of the high spin content on P-450C21 reduction by NADPH in the reconstituted system was analyzed by a steady-state method and by a stopped-flow method at 25 degrees C. The steady-state results showed that the rate of P-450C21 reduction was not affected by the high spin content of substrate-bound P-450C21 but was very slow without a steroid substrate. Biphasic reduction of P450C21 containing two first-order processes was observed in the stopped-flow experiment in the presence of either of the steroid substrates, but the reduction was very slow without the substrate. There were no significant differences in the rate and the amount of the fast phase of reduction between 17 alpha-hydroxyprogesterone-bound and progesterone-bound P-450C21. Both kinetic studies indicate that the spin state does not control the electron transfer from NADPH to P-450C21 via NADPH-cytochrome P-450 reductase but the presence of substrate is essential for the reduction of P-450C21.

Adrenal Cortex↗
PubMed1979

Electron paramagnetic resonance studies of the purified cytochrome P-450scc and P-45011beta from bovine adrenocortical mitochondria.

Electron paramagnetic resonance studies have been carried out on two species of cytochrome P-450 (P-450scc and P-45011beta) purified from bovine adrenocortical mitochondria. The g values of the steroid-bound cytochromes in the high spin form were determined at 4.2 degrees K to be 8.07, 3.60 and 1.70 for P-450scc and 8.00, 3.65 and 1.71 for P-45011beta. The E/D values were estimated to be 0.103 for P-450scc and 0.099 for P-45011beta. Either high spin P-450 was converted into the low spin form by the treatment with an NADPH dependent electron donating system and subsequent gel filtration in order to remove the steroid. The g values of the low spin ferric cytochromes were 2.423, 2.247 and 1.914 for P-450scc and 2.430, 2.251 and 1.919 for P-45011beta at 77 degrees K. The values for magnitude of delta/gamma, magnitude of V/gamma and k were 5.69, 5.21 and 1.11 for P-450scc and 5.94, 5.38 and 1.16 for P-45011beta. These studies indicate that there are some differences in the ferric heme environment between P-450scc and P-45011beta.

Adrenal Cortex↗
PubMed1979

Cerebral contribution to the visual suppression of vestibular nystagmus.

Thirty-two patients with cerebral lesions were examined to locate cerebral areas involved in visual suppression. Visual suppression was reduced or abolished when the lesions were in the parietal lobe, especially in the dorsoposterior region. This part of the parietal lobe seems to modify visual suppression of caloric nystagmus that is mediated by the flocculus and nodulus of the cerebellum as well as the pons. In patients with frontal lobe lesions including the parietal lobe, visual suppression was reduced or abolished. Thus, the parietal lobe is important for this visual suppression mechanism.

Adult↗
PubMed1979

Eye movements associated with eye closure. I. Normal subjects.

Eye movements associated with eye closure were studied in 36 normal adults, and they were recorded by DC amplifiers of ENG. (1) Eyes moved 64 +/- 17 degrees upward and were adducted 15 +/- 7 degrees when eyes were closed. (2) The vertical eye position was held upwards in 33 persons and slightly turned down in 3 persons. (3) The superior rectus and inferior oblique muscles worked together during eye closure.

Adult↗
PubMed1979

Eye movements associated with eye closure. II. Down turning of eye ball elevation.

DC recordings of horizontal and vertical eye movements of various neurological patients were made in an attempt to specify the mechanism underlying sustained eye ball elevation associated with eye closure. Sudden or gradual down turning of vertical eye ball elevation was seen in the following groups: (1) acute stage of inner ear hypo- or afunction; (2) lateral lesions of the cerebellum; (3) acute stage of cerebellar inflammation, and (4) some cases of cerebral lesions. The following pathway seems to be the simplest which would account for these findings: anterior semicircular canal leads to superior vestibular nucleus leads to brachium conjunctivum leads to oculomotor nucleus leads to superior rectus muscle (ipsilateral) and inferior oblique muscle (contralateral).

Adult↗
PubMed1979

The mechanism of inhibition of caloric nystagmus by eye closure.

24 normal adults and 324 clinical cases were examined, for the purpose of shedding light on the mechanism of inhibition of caloric nystagmus by eye closure. When the eyes were closed, an eye was suddenly adducted 13 +/- 5 degrees and elevated 55 +/- 11 degrees. These adductive and upward eye movements were normal responses caused by eye closure. Caloric nystagmus was inhibited by upward eye deviation. With the turning down of the vertical eye position, the caloric-nystagmus inhibition was released. During eye closure, there were four types of vertical eye-movement responses: (a) holding the eye position up, (b) fluctuation around an upward eye position, (c) gradual downward turning, (d) sudden downward turning, Types a, b and c were seen in normal subjects. However, type d was not seen in normal people.

Caloric Tests↗