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Biomedical subjects

Y Oka

Publications and source records attributed to Y Oka.

At least 487 records · Page 27Linked to original sources
PubMed1986

Retinopetal projections from a subpopulation of ganglion cells of the nervus terminalis in the dwarf gourami (Colisa lalia).

The ganglion cells of the nervus terminalis (NT cells) of the dwarf gourami could be classified into type I (giant) and type II (medium to large) cells. After unilateral application of cobaltic-lysine to the optic nerve, only the type II NT cells on the contralateral side were retrogradely labelled. The dendrites ramified near the cell bodies and invaded the olfactory bulb. The axons ran caudally, while taking dorsal and ventral courses, through the ventral telencephalon and the lateral preoptic area, and entered the optic tract.

Animals↗
PubMed1986

Rearrangement of immunoglobulin heavy chain genes and T3 expression in the absence of rearrangement of T-cell receptor beta-chain gene in a patient with T-cell malignant lymphoma.

We describe the rearrangement of immunoglobulin genes and T3 expression in the absence of rearrangement of T-cell receptor beta-chain genes in a patient with T-cell malignant lymphoma. He had a mediastinal mass and his lymphoma cells expressed T-cell antigens (OKT3+, OKT9+, and OKT10+). When we examined genomic DNA from the lymphoma cells, we detected the rearrangement of immunoglobulin heavy chain genes with a germ-line configuration of light chain genes and no rearrangement of T-cell receptor beta-chain gene. These results indicated that the rearrangement of immunoglobulin genes could occur in T-cell malignant lymphoma, and that T3 antigen could be expressed prior to the rearrangement of T-cell receptor beta-chain genes under certain circumstances.

Adult↗
PubMed1986

Epidermal growth factor in human milk and the effects of systemic EGF injection on intestinal calcium transport in suckling rats.

Epidermal growth factor (EGF) is a polypeptide that stimulates proliferation and differentiation of a variety of cell types, including intestinal epithelium; it is the agent in human milk that induces mitosis in human fibroblast culture. It has been postulated that EGF in human milk may play an important role in the normal intestinal maturation since specific EGF receptors are present on the surface of intestinal cells. For this reason, human milk samples from mothers delivering prematurely, as well as at term gestation, were analyzed for their content of EGF. Samples from mothers delivering prematurely showed levels of 70 +/- 5 ng ml-1 and those delivering at term had levels of 68 +/- 19 ng ml-1. There was no diurnal variation and no change with length of lactation up to 50 days. Although previous studies demonstrated that subcutaneous injections of EGF given to suckling rats caused changes in morphology and enzyme activities, no studies had demonstrated that EGF caused changes in function. We injected two-week-old suckling rats and three-week-old weanling rats with 0.1 microgram of g-1 BW twice daily for three days. EGF treatment caused a decrease in somatic weight gain, an increase in weight per unit length of bowel, an increase in lactose specific activity and an increase in net calcium transport. In contrast to the two-week-old suckling rats, the EGF had no effect on intestinal function although somatic weight gain was also depressed in three-week-old animals. These findings demonstrate that human milk contains substantial amounts of EGF and that systemic injections of EGF can cause both morphological and functional changes in the intestinal tract of suckling rats.

Animals↗
PubMed1986

[Prevention of colonic ischemia following abdominal aortic aneurysmectomy by measurement of inferior mesenteric artery stump pressure].

To prevent postoperative colon ischemia, the inferior mesenteric artery (IMA) stump pressure measurement was performed in 60 patients undergoing unruptured abdominal aortic aneurysmectomy. IMA stump pressures were more than 40mmHg and IMA/systemic pressure ratios were more than 0.4 in 58 patients. The IMA was ligated in all of these patients. Colon ischemia developed in two of these 58 patients. In one, vigorous retractive trauma to the colon and the mesenterium seemed to be causative, and in the other, division of the branches of the IMA was causative. None of the other 56 patients developed colon ischemia. In remaining two patients, IMA stump pressures were less than 40mmHg and/or IMA/systemic pressure ratios were less than 0.4. In one of these two, reimplantation of the IMA was not performed until 12 hours after ligation of the IMA and postoperative ischemic colitis developed. In the other, the IMA was implanted into the prosthesis and colon ischemia did not develop. These results indicated that IMA stump pressure measurement is simple and very useful method to predict the risk of postoperative colon ischemia following abdominal aortic aneurysmectomy, and when IMA stump pressure or IMA/systemic pressure ratio is less than 40mmHg or 0.4, the IMA should be revascularised.

Adult↗
PubMed1986

[Regional cerebral blood flow (rCBF) in patients with ruptured cerebral aneurysm: site of aneurysm and rCBF].

To investigate the relationship between the site of ruptured cerebral aneurysm and rCBF, 92 measurements of rCBF were conducted in 57 patients with ruptured cerebral aneurysm. Excluded from this study were patients with multiple aneurysms, intracerebral hematoma, and/or hydrocephalus. Twenty-four patients had the anterior communicating aneurysm (A-com), 20 patients had the internal carotid aneurysm (ICA), and 13 patients had the middle cerebral aneurysm (MCA). All patients underwent unilateral fronto-temporal craniotomy for clipping of the aneurysm and their rCBF measurements, using the xenon-133 inhalation method, were performed in the first three weeks after surgery. In each rCBF measurement, the hemispheric mean value of initial slope index (meanISI) was calculated in both cerebral hemispheres, that is, in the cerebral hemispheres ipsilateral and contralateral to craniotomy. The authors defined the "symmetry index of the meanISI (%): symmetry index" as the ratio of the meanISI in the cerebral hemisphere ipsilateral to craniotomy compared to the meanISI in the cerebral hemisphere contralateral to craniotomy. There was no significant relationship between the site of aneurysm and the meanISI in both hemispheres, and this result suggests that the site of aneurysm makes no difference in the incidence of vasospasm. In the postoperative first week, the "symmetry index" was 91.2 +/- 7.4% in MCA, 95.3 +/- 4.1% in ICA, and 97.9 +/- 8.2% in A-com; that is, MCA had significant asymmetry of meanCBF compared with A-com (p less than 0.05). In the second and third postoperative weeks, there was no significant relationship between the site of aneurysm and the asymmetry of meanCBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrovascular Circulation↗
PubMed1986

Retained intracardiac air. Transesophageal echocardiography for definition of incidence and monitoring removal by improved techniques.

Retained intracardiac air is a continuing hazard for cardiopulmonary bypass. M-mode transesophageal echocardiography of the left atrium, left ventricle, and aorta is a highly sensitive method for detecting retained intracardiac air bubbles. In 15 patients having valve operations and 18 having coronary bypass, M-mode transesophageal echocardiography was used to record air bubbles during and for 15 minutes after bypass. Routine air clearing methods were used: needle aspiration of the ascending aorta (combined coronary and valve operations) and left atrial, left ventricular, and aortic aspiration after careful passive chamber filling (valve operations). Air was detected in 12 of 15 (79%) patients having valve operations and two of 18 (11%) patients having coronary bypass. One with air in the aorta had visible right coronary air embolism. Three patients with positive echograms had transient central nervous system disturbances. In a further 11 patients having valve operations, an ascending aorta-venous shunt was created before bypass was discontinued, but air continued to be present in the left atrium. Finally, in seven patients, we added the following maneuvers to our routine: positive chamber filling with echocardiographic demonstration of left atrial stretching, vigorous chamber ballottement, specific echo-directed chamber aspiration, and maintenance of cardiopulmonary bypass until transesophageal echocardiography showed no retained air. Although small amounts of atrial air could still be detected for a minute or two in some patients, this technique appears finally to have eliminated significant retained air and its consequences. A sensitive technique for intracardiac air detection reveals retained air surprisingly often after cardiopulmonary bypass. There are both possible and probable adverse consequences of this air. After valve operations, it is most difficult to eliminate air from the left atrium. There are three essential elements of air removal: First is mobilization of the air; positive chamber filling, stretching of the atrial wall, and ballottement are critical. Second is removal of mobilized air; continuous ascending aorta-venous shunting and nonsuction venting of the left atrium are very important. Third is proof of elimination of air before cardiopulmonary bypass is terminated; transesophageal echocardiography is vital for this.

Adult↗
PubMed1986

[Cavoatrial bypass in obstruction of the inferior vena cava in the hepatic portion through the posterior route of the hepatic caudate lobe].

In a 32-year-old Japanese female who had a history of Sjögren's syndrome, the obstruction of the inferior vena cava in the hepatic portion was found associated with Budd-Chiari syndrome. The obstruction of the inferior vena cava was about 6 cm in length by cavography. Cavoatrial bypass grafting was successfully performed with a 16 mm ring reinforced expanded polytetrafluoroethylene graft, which ran behind the caudate lobe of the liver and connected to the right atrium via right pleural cavity. This may be the first report of the posterior route of the hepatic caudate lobe in cavoatrial bypass grafting in Japanese and English literature.

Adult↗
PubMed1985

An HRP study of afferent connections of the supracommissural ventral telencephalon and the medial preoptic area in himé salmon (landlocked red salmon, Oncorhynchus nerka).

The supracommissural ventral telencephalon and the medial preoptic area have been shown to play important roles in the sexual behavior of himé salmon (landlocked red salmon, Oncorhynchus nerka). In the present study, the sites of neurons projecting to these regions were examined by means of the retrograde horseradish peroxidase (HRP) tracing method. The morphology of neurons in these sites of origin was also studied by means of the Golgi method. The nucleus preopticus periventricularis and the rostral part of nucleus preopticus (NPP-rNPO) received bilateral projections from the middle parts of the area ventralis telencephali pars ventralis (Vv) and the area ventralis telencephali pars dorsalis (Vd), NPP and lateral part of the preoptic area (LPOA), ipsilateral projections from the caudal part of Vv, nucleus anterioris periventricularis (NAPv), nucleus ventromedialis thalami (NVM) at the level of the posterior commissure, nucleus lateralis tuberis pars medialis (NLTm), nucleus anterior tuberis (NAT), nucleus saccus vasculosus (NSV), nucleus recessus posterioris (NRP) and midbrain tegmentum (TG), and a projection from the nucleus posterior tuberis (NPT), which is situated on the midline of the brain. The area ventralis telencephali pars supracommissuralis and neighboring caudal ventral telencephalon (Vs-cV) received ipsilateral projections from almost all parts of the Vv, the middle and caudal parts of Vd, almost all parts of the NNP, the NPO at the level between the habenula and the posterior commissure, and the rostral part of the nucleus dorsomedialis thalami (NDM). The Vs-cV also received a projection from NPT. These findings seem to give anatomical bases for understanding the neural mechanisms involved in sexual behavior as well as neuroendocrine functions.

Afferent Pathways↗
PubMed1985

Direct demonstration of rapid insulin-like growth factor II Receptor internalization and recycling in rat adipocytes. Insulin stimulates 125I-insulin-like growth factor II degradation by modulating the IGF-II receptor recycling process.

The photoactive insulin-like growth factor (IGF)-II analogue 4-azidobenzoyl-125I-IGF-II was synthesized and used to label specifically and covalently the Mr = 250,000 Type II IGF receptor. When rat adipocytes are irradiated after a 10-min incubation with 4-azidobenzoyl-125I-IGF-II at 10 degrees C and immediately homogenized, most of the labeled IGF-II receptors are associated with the plasma membrane fraction, indicating that receptors accessible to the labeling reagent at low temperature are on the cell surface. However, when the photolabeled cells are incubated at 37 degrees C for various times before homogenization, labeled IGF-II receptors are rapidly internalized with a half-time of 3.5 min as evidenced by a loss from the plasma membrane fraction and a concomitant appearance in the low density microsome fraction. The low density microsomes were previously shown to contain intracellular membranes (Oka, Y., and Czech, M.P. (1984) J. Biol. Chem. 259, 8125-8133). The steady state level of cell surface IGF-II receptors in the presence or absence of IGF-II, measured by the binding of anti-IGF-II receptor antibody to cells, remains constant under these conditions, demonstrating that IGF-II receptors rapidly recycle back to the cell surface at the same rate as receptor internalization. Using the above methodology, it is shown that acute insulin action: 1) increases the steady state number of cell surface IGF-II receptors; 2) increases the number of ligand-bound IGF-II receptors that are internalized per unit of time, as evidenced by a large increase in the photolabeling of intracellular membrane IGF-II receptors when cells are incubated at 37 degrees C with insulin and 4-azidobenzoyl-125I-IGF-II prior to photoactivation; and 3) increases the rate of cellular 125I-IGF-II degradation by a process that is blocked by anti-IGF-II receptor antibody. The results indicate that the action of insulin to elevate the steady state number of cell surface IGF-II receptors leads to an increased internalization flux of IGF-II-bound receptors, mediating increased IGF-II uptake and degradation.

Adipose Tissue↗
PubMed1985

A case of spontaneous regression of hepatocellular carcinoma with bone metastasis.

A 78-year-old Japanese man with chronic liver disease developed hypervascular liver tumors accompanied by marked elevation of alphafetoprotein value (the highest level; 26200 ng/ml) and pathologic fracture of the femur. After an operation for the fracture followed by gastrointestinal bleeding and repeated transfusions of blood, the tumors disappeared with normalization of the alpha-fetoprotein level, and the radiolucent area around the fracture site of the femur became consolidated. The necrotic tissue responsible for the fracture histologically showed an appearance of hepatocellular carcinoma. The patient survives 62 months after the initial increase in alpha-fetoprotein level. This is a case of spontaneous regression of both hypervascular liver tumors which are highly suggestive of hepatocellular carcinoma and their metastasis.

Aged↗
PubMed1985

Transcatheter arterial embolization for hepatocellular carcinoma. Benefits and limitations for unresectable cases with liver cirrhosis evaluated by comparison with other conservative treatments.

Transcatheter arterial embolization (TAE) for unresectable hepatocellular carcinoma (HCC) was performed in cirrhotic patients with nonoccluded main portal trunk and total bilirubin levels less than 5 mg/dl. In 48 patients with tumor response to TAE, its benefit was evaluated by comparing their survival with that in 28 patients after conservative treatments, matched by clinical data. In TAE-treated patients, tumor findings on computerized tomography and angiogram were significantly different between those dying within 3 months and those surviving over 18 months. In cases of tumors occluding the first- or second-order portal branches or occupying more than 20% of the liver, or relatively hypovascular tumors with unclear boundaries, survival was not different between TAE- and non-TAE-treated patients, whereas it was significantly improved by TAE in cases without these findings. These results suggest that TAE is beneficial in cases of unresectable HCC complicating liver cirrhosis, but its benefit is limited under certain conditions.

Adult↗
PubMed1985

Benefit of transcatheter arterial embolization for ruptured hepatocellular carcinoma complicating liver cirrhosis.

In 6 patients with spontaneous rupture of hepatocellular carcinoma complicating liver cirrhosis, but with no occlusion of the main portal trunk, transcatheter arterial embolization was performed within 7 days of the rupture. All 6 patients were thought to be inoperable because of shock state or severe hepatic dysfunction. In all 6 patients, the progressive decrease in the hematocrit ceased soon after the embolization. Five patients survived for 31-168 days after the embolization; 1 patient who developed septicemia died 10 days later. We conclude that transcatheter arterial embolization is beneficial as a procedure of first choice for ruptured hepatocellular carcinoma when the portal blood flow is maintained.

Adult↗
PubMed1985

Efferents from the supracommissural ventral telencephalon in the hime salmon (landlocked red salmon, Oncorhynchus nerka): an anterograde degeneration study.

Efferents from the area ventralis telencephali pars supracommissuralis (Vs) of hime salmon (landlocked red salmon, Oncorhynchus nerka) were studied using anterograde degeneration methods. It was found that Vs sends intratelencephalic fibers bilaterally to the internal cell layer of the olfactory bulb and wide areas of telencephalon, while it sends extratelencephalic fibers bilaterally to habenulae, inferior lobes and midbrain tegmenti through medial and lateral forebrain bundles and lateral preoptic area. A possibility was pointed out that some of these extratelencephalic projections are involved in the pathway controlling the sexual behavior which are suggested from behavioral experiments.

Animals↗