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Biomedical subjects

K Mihara

Publications and source records attributed to K Mihara.

At least 235 records · Page 13Linked to original sources
PubMed1980

The four cytoplasmically made subunits of yeast mitochondrial cytochrome c oxidase are synthesized individually and not as a polyprotein.

Subunit-specific antisera prepared against each of the four cytoplasmically made subunits (IV, V, VI, and VII) of yeast mitochondrial cytochrome c oxidase (EC 1.9.3.1) were used to precipitate immunoreactive polypeptides that were synthesized either in vitro, in a cell-free protein-synthesizing system programmed with total yeast mRNA, or in vivo, in intact cells and in spheroplasts, under conditions of pulse labeling, pulse-chase labeling, and continuous labeling. Using N-formyl-[35S]Met-rTNA as the only radioactively labeled component in the cell-free system, we demonstrated (i) that each of the four cytoplasmically made subunits is synthesized as a separate entity and not as part of a polyprotein as was claimed by others; (ii) that subunits IV, V, and VI are synthesized as precursors, larger by 1500-3000 daltons than their mature counterparts; in contrast, subunit VII is not synthesized as a larger precursor. Precursor forms of subunits IV, V, and VI identical to those synthesized in vitro were also detected in vivo by pulse-labeling of spheroplasts. The observed disappearance of these larger forms after a chase is compatible with the notion that they represent short-lived precursors that are rapidly converted to their mature counterparts during or shortly after import into mitochondria. Furthermore, using N-formyl-[35S]Met-tRNA, we provide definitive evidence that two of the cytoplasmically made subunits (beta and gamma) of another oligomeric inner mitochondrial membrane protein (F1-ATPase, EC 3.6.1.3) are not synthesized as part of a polyprotein but as individual precursors.

Adenosine Triphosphatases↗
PubMed1980

Radiosensitive meningioma.

A hugh intracranial angioblastic meningioma responded well to preoperative irradiation. The indication for preoperative irradiation of hypervascular and inaccessible meningiomas is discussed.

Adult↗
PubMed1979

Echocardiographic findings in patients with aortitis syndrome.

Echocardiography was performed in 18 patients with the aortitis syndrome and in 20 age-matched normal volunteers. The aortic root dimension, the aortic dimension at the level of the sinotubular ridge, the aortic arch dimension, the left ventricular internal dimension, the left atrial dimension, the interventricular septal thickness, and the left ventricular posterior wall thickness were measured. All measurements, except for the left atrial dimension, were significantly greater in patients with aortitis syndrome than in the control subjects. We concluded (1) that the patients with the aortitis syndrome may have an enlarged or narrowed aorta, a dilated left ventricle and left atrium, and a thickened interventricular septum and left ventricular posterior wall; (2) that the incidence and the degree of these abnormalities depend on the presence of complications such as aortic regurgitation and arterial hypertension; and (3) that M-mode as well a cross-sectional echocardiography plays an important role in the assessment of the aorta and heart in the aortitis syndrome.

Adolescent↗
PubMed1978

Reduced nicotinamide adenine dinucleotide-cytochrome b5 reductase: location of the hydrophobic, membrane-binding region at the carboxyl-terminal end and the masked amino terminus.

Microsomal NADH-cytochrome b5 reductase is an amphiphilic protein consisting of a hydrophilic (catalytic) region and a hydrophobic (membrane-binding) segment. Digestion of the reductase purified from rabbit liver microsomes with carboxypeptidase Y (CPY), but not with aminopeptidases, resulted in the abolishment of the capacities of the reductase to bind to phosphatidylcholine liposomes and to reconstitute an active NADH-cytochrome c reductase system upon mixing with cytochrome b5. The NADH-ferricyanide reductase activity of the flavoprotein was, however, inactivated only slightly by the CPY digestion. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino acid analyses indicated that the CPY treatment removed about 30 amino acid residues from the tcooh terminus of the reductase and that about 70% of the amino acids released were hydrophobic. It is concluded that the hydrophobic region of the reductase, responsible for both membrane binding and effective reconstitution of NADH-cytochrome c reductase activity, is located at the COOH-terminal portion of the molecule. No NH2-terminal residue could be detected in the intact and CPY-modified reductase preparations. The location of the hydrophobic, membrane-binding segment at the COOH-terminal end and the masked NH2 terminus have also been reported for cytochrome b5, another microsomal membrane protein.

Amino Acids↗
PubMed1978

Psychosomatic aspects of the effect of conjugated estrogens in patients with postoperative ovarian deficiency syndrome.

Fifty-three uterine cancer patients who complained of the syndrome dur to vasomotor manifestations or psychosomatic response after ovariectomy were given Premarin tablets, 1.25 mg per day or placebo for 3 weeks and improvement in their complaints was compared from the psychosomatic aspects by the double-blind method. Premarin was significantly more effective than placebo (P less than 0.001) in the psychologically normal patients. On the other hand, no difference in the effectiveness of these drugs were found in the psychologically abnormal patients (P = 0.119). According to the self evaluation by the patients, Premarin was significantly more effective than placebo (P less than 0.05) in the psychologically normal patients. However, there was no difference in the effects of these agents in the psychologically abnormal patients.

Adult↗
PubMed1975

[Neuroradiologic diagnosis of trigeminal neurinoma originating from the gasserian ganglion (author's transl)].

Three cases of trigeminal neurinoma originating from the Gasserian ganglion were reported. The findings observed on plain roentgenograms, cerebral angiograms and pneumoencephalograms were described in detail. Neuroradiologic examinations used routinely our department for the diagnosis of the skull base tumors were as follows; (1) plain skull examinations, including lateral, straight posterior-anterior, anterior-posterior half axial (Towne), axial, Stenvers, optic canal as well as tomograms in frontal, sagittal and axial projections; (2) angiographies by transfemoral catheter technique including selective internal carotid, external carotid and vertebral angiograms, and orbital-cavernous sinus venography via frontal and femoral veins; (3) pneumoencephalography with tomography. Bone destruction of the middle fossa including foramen ovale, foraman spinosum and lateral aspect of the sella was seen in all cases. Superior orbital fissure, optic canal and anterior surface of the petrous bone were also eroded depending upon the extent of tumors. Sharply circumscribed erosion of the petrous apex was seen in one of 3 cases, indicating the tumor extention into the posterior fossa. A soft tissue mass in the sphenoid sinus and ethmoidal air cells was recognized in all cases. Selective internal and external carotid angiograms demonstrated tumor vessels in 2 of 3 cases. Orbital-cavernous sinus venography was helpful for the interpretation of the lesion extending to the cavernous sinus and its neighboring structures. Conventional gas encephalography showed elevation of the temporal horn, and the concave arch formed by the supracornual cleft and lateral cleft was directed basally and medially in all of the cases. Tomography was also useful in the more detailed analysis of temporal horn. It should be stressed that the plain skull features are most important for deciding which contrast examination should be performed further.

Adult↗