Search PubMed⌕ Search

Biomedical subjects

Y Oka

Publications and source records attributed to Y Oka.

At least 469 records · Page 26Linked to original sources
PubMed1987

Differentiation of an Abelson virus-transformed immature B precursor cell line under the expression of tyrosine kinase activity of v-abl oncogene product.

The expression of v-abl oncogene during the in vitro differentiation of an Abelson-virus-transformed immature B precursor cell line from immunoglobulin-null to intracytoplasmic mu-positive cells and further to intracytoplasmic gamma 2b-positive cells was examined. The results showed no significant alteration in the amounts and tyrosine kinase activity of v-abl oncogene product during differentiation, indicating that B cell differentiation processes are independent of v-abl functions.

Abelson murine leukemia virus↗
PubMed1987

Role of cell-surface modulator of DNA synthesis in liver regeneration.

A cell-surface modulator of DNA synthesis by cultured rat hepatocytes was studied in relation to the liver regeneration process. When rat hepatocytes isolated 24 h after partial hepatectomy were cultured, the first burst of DNA synthesis peaked at 5-8 h and declined until 24 h, followed by the second burst. Rat liver plasma membranes added 2 h after plating inhibited only the second burst, while in the case of the normal hepatocytes where the DNA synthesis began to increase after 5 h, this inhibition was observed at 16 h but not at 8 h. The inhibition did not differ when the membranes obtained from regenerating livers 12 h after partial hepatectomy were used. Epidermal growth factor binding to the cultured hepatocytes was not hindered by the membranes. These results suggest that the modulator inhibits hepatocyte proliferation at the early G1-phase of the cell cycle and that its action might be controlled by other factors in the process of liver regeneration.

Animals↗
PubMed1987

Intranephron distribution of epidermal growth factor immunoreactivity in the mouse.

Using a specific and sensitive epidermal growth factor (EGF) radioimmunoassay, the distribution of EGF in mouse kidneys was studied. In five portions (outer cortex, inner cortex, outer medulla I, II, and papilla) of kidney slices, the outer medulla revealed the highest immunoreactive EGF (iEGF) per wet weight of tissue. In microdissected nephron segments, the predominant iEGF per millimeter length was observed in the medullary and cortical thick ascending limbs of Henle's loop compared with other segments. It became more apparent when expressed per milligram protein. Fluorescence microscopy showed prominent staining for EGF in the thick ascending limbs of Henle's loop. The significance of the nephron heterogeneity in EGF contents is discussed.

Animals↗
PubMed1987

Mitral valve prolapse in patients with anorexia nervosa. Two-dimensional echocardiographic study.

To examine the prevalence of mitral valve prolapse (MVP) and to define the mechanisms of its development in patients with anorexia nervosa, we studied the cardiac function of 23 patients with anorexia nervosa by two-dimensional (2-D) echocardiography. MVP was present in 19 of 23 patients (82.6%), 10 having double MVP in both the anterior and posterior mitral leaflets and 9 having a single MVP in the anterior leaflet. There was no difference in echocardiographic parameters between the MVP(+) and MVP(-) groups. The heart rate was lower in the double MVP group (46.3 +/- 8.1; mean +/- SD) than in the non MVP group (64.0 +/- 6.3; p less than 0.01) and the single MVP group (55.9 +/- 10.9; p less than 0.05). The presence of bradycardia in these patients suggests an increase in vagal tone. The present study suggests that the incidence of MVP in anorexia nervosa is among the highest compared with its incidence in association with any other disorders, and an increase in vagal tone may be responsible for the development of MVP in patients with anorexia nervosa.

Adolescent↗
PubMed1987

[A clinicopathological evaluation of AFP-positive gallbladder cancer--with special reference to two autopsy cases investigated by an immunological method].

We report on 2 autopsy cases of primary gallbladder cancer in which the serum AFP level was found to be above 1000 ng/ml. Both cases showed a hepatic metastasis and a moderately differentiated papillary adenocarcinoma. We investigated the primary and metastatic parts by means of an immunological technique and found them to be AFP positive. Gallbladder cancer cases at our hospital that have been evaluated as being AFP positive remain an object of our cancer as to its clinical pathological meaning.

Adenocarcinoma↗
PubMed1987

[Combination chemotherapy of UFT, etoposide and CDDP in advanced gastric cancer].

Eleven patients with advanced unresectable gastric cancer were treated with a combination of UFT, etoposide and CDDP (FFP). FEP regimen was given every 4 weeks as follows: UFT 400 mg/m2 (p.o.) everyday, etoposide 50 mg/m2 (i.v.), and CDDP 30 mg/m2 (i.v.) on day 1, 8, and 15. The subjects were 3 males and 8 females with an average of 64 (ranging from 44 to 84 yrs). None had had prior chemotherapy. One patient was in performance status (P.S.) 1, 6 were in PS 2, and 4 were in PS 3. Partial responses (PR) were obtained in 5 out of 11 patients. The durations of the response were over 3 months in all patients with PR. No side effects were observed except for mild myelosuppression and nausea. In BALB/C mice with lymphoid leukemia L1210, the effects of each drug and the combination of the two or three drugs on the increase in life span (ILS) were studied. The combination of the three drugs showed the highest effect on ILS. In conclusion, it is suggested that FEP chemotherapy is useful for advanced gastric cancer.

Adult↗
PubMed1987

[Mitral valve prolapse in patients with anorexia nervosa].

Mitral valve prolapse was echocardiographically examined for 23 female patients with anorexia nervosa. The age was ranged from 13 to 26 and averaged 19.6 years. Their body weights ranged from -25 to -45% of the ideal body weights. Mitral valve prolapse was detected in 19 (83%) cases. The involved valve leaflets were anterior and posterior in 10 and anterior in nine cases, and significant bradycardia was present in the former. Left ventricular end-diastolic dimension was less than the control subjects. The follow-up study in five patients disclosed that each prolapse was unchanged despite of the significant improvement of the disease. The involved mechanism of prolapse in patients with anorexia nervosa was discussed in the light of vagotony based on the pharmacodynamic tests and the results of the previous experimental works of Imataka et al.

Adolescent↗
PubMed1987

[Obstruction of the inferior vena cava at the hepatic portion--surgical management and prognosis of 11 cases].

Eleven patients with obstruction of the inferior vena cava at the hepatic portion were reviewed. In these patients, 7 had membranous obstruction and underwent balloon membranotomy. Pressure gradient between inferior vena cava and right atrium was 13.1 +/- 5.1 mmHg (mean +/- S.D.) and after membranotomy, this fell down to 7.0 +/- 1.9 mmHg. Four patients had long segmental obstruction, and cavoatrial bypass grafting with 16 mm ring reinforced Expanded-Polytetrafluoroethylene graft in 3 and bidirectional digital-instrumental membranotomy in one, were done, respectively. In 2 of 7 patients with membranous obstruction, transcardiac membranotomy was followed. These 3 procedures were so effective that pressure gradient between inferior vena cava and right atrium was 11.7 +/- 3.4 mmHg preoperatively, and after operation, this fell down to 1.7 +/- 0.7 mmHg. During the follow-up period from 8 months to 9 years (mean 4 years and one month), all patients are alive with remarkable improvement of clinical symptoms and signs. It is concluded that balloon membranotomy for membranous obstruction and cavoatrial bypass grafting for long segmental obstruction of the inferior vena cava at the hepatic portion would be recommended.

Adolescent↗
PubMed1987

[Extracranial internal carotid occlusion and coexisting ipsilateral intracranial internal carotid aneurysm].

A rare case of extracranial internal carotid occlusion with a coexisting ipsilateral internal carotid aneurysm is reported. A 50-year-old male had a sudden onset of severe headache, vomiting and right motor weakness on May 14, 1984. Two days later the patient was transferred to our hospital. On admission he was alert but presented with nuchal rigidity and right moderate hemiparesis. He had an episode of a blunt head injury 12 years previously, but no history of hypertension, diabetes mellitus or cerebral stroke. A computed tomography revealed mild subarachnoid hemorrhage and mild ventricular dilatation. A cerebral angiography did not demonstrate any aneurysms but it revealed occlusion of the right internal carotid artery at the cervical bifurcation. The repeated angiography on May 31 disclosed a saccular aneurysm arising anteromedially at the level of the junction of the right posterior communicating artery and the internal carotid artery. The cervical internal carotid artery remained occluded at the same site. The middle cerebral artery was supplied through the well-developed posterior communicating artery, and the right anterior cerebral artery was supplied through the anterior communicating artery. Clipping of the aneurysm was attempted but it was forcibly trapped because of premature bleeding on June 5. The right V-P shunt was performed for the progressive ventricular dilatation on June 12. The patient was discharged with no paresis on June 20. It has been well known that the uni- or bilateral carotid occlusion, whatever the origins are, are often associated with cerebral aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid Artery Diseases↗
PubMed1986

Descending pathways to the spinal cord in the himé salmon (landlocked red salmon, Oncorhynchus nerka).

Distribution and morphology of the cells of origin of the descending spinal pathways and their axonal courses were studied in the himé salmon, using retrograde labelling with cobaltic lysine and horseradish peroxidase (HRP). Following application of the tracers to the cut end of the spinal cord or injection of the tracers at the 10th to 15th spinal segment, neurons mainly labelled via the axons of passage were distributed in the mesencephalon and the rhombencephalon. Mesencephalic cell groups consisted of the nucleus pretectalis, the nucleus fasciculi longitudinalis medialis, and the nucleus ruber. The former two cell groups sent their axons to the fasciculus longitudinalis medialis. The axons of the nucleus ruber formed a separate loose bundle, the "tractus rubrospinalis." The rhombencephalic cell groups consisted of the rhombencephalic reticular formation, the Mauthner cells (one cell for each side), and the octavolateral area. The rhombencephalic reticular formation could be further subdivided into the nucleus reticularis superior, nucleus reticularis medius, and nucleus reticularis inferior. The axons of these cell groups joined the fasciculus longitudinalis medialis and the "tractus bulbospinalis." The Mauthner cell had two main gigantic dendrites, and its giant axons formed a conspicuous fiber of Mauthner throughout the rhombencephalon down to the spinal cord. The octavolateral area could be subdivided into the nucleus vestibularis magnocellularis, nucleus tangentialis, nucleus vestibularis descendens and nucleus intermedius. The axons of the nucleus vestibularis magnocellularis and nucleus intermedius entered the fasciculus longitudinalis medialis and/or the tractus bulbospinalis. Those of the nucleus vestibularis descendens and nucleus tangentialis formed the "tractus vestibulospinalis". The descending spinal pathways of the himé salmon were compared with those of other fishes and other vertebrates. The significance of these descending spinal pathways in the control of locomotion and sexual behavior is also discussed.

Animals↗
PubMed1986

Ascending pathways from the spinal cord in the himé salmon (landlocked red salmon, Oncorhynchus nerka).

The ascending pathways from the spinal cord of the himé salmon were anterogradely labelled by the cobaltic lysine method, and their courses and terminations were examined. Following application of the cobaltic lysine to the cut end of the spinal cord or injection of the cobalt at the 10th to 15th spinal segment, labelled axons were traced from the spinal cord to various regions in the rhombencephalon and the mesencephalon. The axons ascending from the dorsal funiculus gave off many terminals as they ascended to the lower medulla. This terminal area may be homologous to the nucleus funiculi dorsalis of other vertebrates, although cytoarchitectural differentiation of the area is not evident. The dorsal funicular fibers also formed some terminals in the vagus and glossopharyngeal motor nuclei and the nucleus fasciculi solitarii. The axons arising from the anterolateral funiculus ascended as the common trunk of the lemniscus spinalis. The lemniscus spinalis fibers distributed many axon terminals on their way through the lower medulla, and most probably made synaptic contacts with the peripheral dendrites of the cells of origin of the reticulospinal pathways throughout its rostrocaudal extent. They also projected to all the medullary cranial nerve motor nuclei (V, VI, VII, IX, and X). The rostral continuation of the lemniscus spinalis fibers entered the lemniscus lateralis and gave a rostrocaudally elongated terminal area in the nucleus lateralis of the torus semicircularis.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1986

The type II insulin-like growth factor receptor is internalized and recycles in the absence of ligand.

Recent studies have demonstrated that ligand-bound insulin-like growth factor (IGF)-II receptors on the adipocyte cell surface are rapidly internalized into an intracellular membrane fraction prior to recycling to the plasma membrane (Oka, Y., Rozek, L. M., and Czech, M. P. (1985) J. Biol. Chem. 260, 9435-9442). In order to evaluate whether these subcellular movements of IGF-II receptors in fat cells require their binding to ligand, cell surface IGF-II receptors of insulin-treated fat cells were iodinated with Na125I and lactoperoxidase at 15 degrees C. IGF-II receptors were then localized by immunoadsorption from solubilized cell surface plasma membranes and intracellular low density microsomes derived from labeled cells. When fat cells were homogenized immediately after iodination, most of the labeled IGF-II receptors were associated with the plasma membrane fraction. However, when iodinated fat cells were incubated at 37 degrees C for various times before homogenization, labeled IGF-II receptors progressively decreased in the plasma membrane fraction and concomitantly increased in the low density microsome fraction with a half-time of about 5 min. The rate of increase of radiolabeled IGF-II receptors appearing in the low density microsomes of labeled fat cells incubated with insulin was not changed by the addition of a saturating concentration of IGF-II. These results indicate that cell surface IGF-II receptors are rapidly internalized and recycled even in the absence of ligand binding in insulin-treated adipocytes.

Adipose Tissue↗