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Biomedical subjects

Y Oka

Publications and source records attributed to Y Oka.

At least 523 records · Page 29Linked to original sources
PubMed1984

Involvement of the telencephalic hemispheres and the preoptic area in sexual behavior of the male goldfish, Carassius auratus: a brain-lesion study.

To locate the brain areas involved in sexual behavior, the effects on male sexual behavior of localized electrolytic lesions in various parts of the telencephalic hemispheres and the preoptic area and of gross ablations of parts of the telencephalic hemispheres were examined in goldfish. All three patterns of male sexual behavior examined (following, butting , and spawning) were severely impaired after bilateral lesions confined to the area ventralis telencephali pars supracommissuralis and/or posterior parts of the area ventralis telencephali pars ventralis (Vs- pVv ), the nucleus preopticus periventricularis (NPP), the lateral forebrain bundle ( LFB ), or the medial forebrain bundle (MFB). On the other hand, sexual behavior was almost unaffected after bilateral ablations of the anterior part or lateral and dorsal parts of the telencephalic hemispheres (AT or LT-DT). Bilateral lesions confined to the area ventralis telencephali pars dorsalis (Vd), the area ventralis telencephali pars postcommissuralis (Vp), the area dorsalis telencephali pars centralis (Dc), the nucleus preopticus (NPO), or the lateral preoptic area (LPA) also had almost no effect on sexual behavior. These results indicate that a particular site in the ventral part of the telencephalic hemispheres (Vs- pVv ) and the anterior part of the preoptic area (NPP) play important roles in the sexual behavior of male goldfish. It was suggested that facilitatory influences from these areas are transmitted through the LFB and/or the MFB.

Animals↗
PubMed1984

Insulin activates the appearance of insulin-like growth factor II receptors on the adipocyte cell surface.

To evaluate the mechanism of insulin action to increase rat 125I-labeled insulin-like growth factor II (125I-IGF-II) binding to rat adipocytes, we raised a potent rabbit antiserum against purified IGF-II receptors from rat placental membranes. The antiserum elicited a positive reaction at a 1:5000 dilution against purified IGF-II receptor in an ELISA and markedly inhibited 125I-IGF-II binding to adipocyte plasma membranes when added prior to the growth factor. Immunoprecipitation lines formed between agar plate wells containing antiserum versus IGF-II receptor, both in the presence and absence of 1 microM IGF-II, indicating that binding of anti-receptor Ig to the IGF-II receptor is not affected by occupancy of the IGF-II binding site. Intact adipocytes treated with or without insulin were incubated with anti-IGF-II receptor Ig, washed, and further incubated with 125I-labeled goat anti-rabbit IgG to monitor the amount of anti-receptor Ig bound. Insulin induced parallel increases in anti-IGF-II receptor Ig binding (2.4-fold) and 125I-IGF-II binding (3-fold) to the isolated cells. The dose-response relationship of insulin action on 125I-IGF-II binding and anti-receptor Ig binding was essentially identical with a half-maximal effect at approximately 0.07 nM insulin. That insulin does not act to expose new types of antigenic sites on IGF-II receptors was indicated by the demonstration that control adipocytes could readily adsorb the anti-receptor Ig. These data demonstrate that increased numbers of IGF-II receptors are displayed in an exposed position on the adipocyte cell surface in response to insulin.

Adipose Tissue↗
PubMed1984

First evidence for the occurrence of N delta-acetyl-L-ornithine and quantification of the free amino acids in the cultivated mushroom, Pleurotus ostreatus.

The free amino acid profile of the fruiting bodies of Pleurotus ostreatus was studied in detail. The first evidence for the occurrence of N delta-acetyl-L-ornithine in the mushroom was presented, and 33 ninhydrin-positive compounds were determined, besides N delta-acetyl-L-ornithine. Alanine, glutamic acid, valine, glutamine, glycine and leucine were predominant protein amino acids occurring in the free form. As regards the non-protein amino acids, ornithine, gamma-aminobutyric acid, saccharopine, alpha-aminoadipic acid, ethanolamine, cystathionine, and N-(gamma-glutamyl)ethanolamine were mainly detected. The sum of the nitrogen of the three abundant amino acids, alanine, glutamic acid and ornithine, accounted for about 40% of the total nitrogen in the amino acid fraction.

Acetates↗
PubMed1984

[Mitral valve prolapse in patients with anorexia nervosa].

Mitral valve prolapse (MVP) is frequently observed in patients with low body weight and/or skeletal abnormalities such as pectus excavatum and straight spines. There may be a variety of associated autonomic dysfunctions. Whether MVP is a complication of anorexia nervosa which has similar clinical features, including weight loss, skeletal abnormalities and autonomic dysfunctions, has not been reported. The present study was an investigation of the incidence of MVP and cardiac function in anorexia nervosa by echocardiography. Two-dimensional and M-mode echocardiography, and systolic time intervals were evaluated for 19 women with anorexia nervosa, from 13 to 25 years of age and having a mean age of 18.2 years. Their body weights ranged from 23.9 to 43 kg with a mean of 33.5 kg, and were at least 25% less than their ideal body weights (ranges were from 25 to 52%). The same studies were performed for 19 women with MVP diagnosed echocardiographically and without anorexia nervosa as controls. Their ages ranged from 14 to 26 years. Results were as follows: MVP was observed in 74% of patients with anorexia nervosa. The mean heart rates were 51.7 and 70.5/min in the anorexia nervosa and control groups, respectively. A significant difference (p less than 0.001) was observed between the two groups. The mean heart rate of patients with anorexia nervosa having MVP of both leaflets and no MVP were 45.8 and 59.0/min, respectively. The difference between these two sub-groups was statistically significant (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Protamine-induced circulatory changes.

The effects of rapid protamine administration via the left and right atria were compared. Preliminary studies first confirmed the safety of protamine administration via these routes, although decreases of up to 20 mm Hg were seen in the systolic blood pressure following protamine injection via the right atrium. Seventeen patients undergoing coronary artery bypass graft were studied, of whom nine received protamine via the right atrium and eight via the left atrium. Measurements of arterial pressure, left and right atrial pressure, cardiac output, and calculation of systemic vascular resistance and left ventricular stroke work index were made before and after protamine administration. Plasma histamine levels were measured in left atrial blood samples in 10 patients, before and after protamine injection. No significant change occurred after injection via the left atrial route, whereas a significant decrease in the systolic blood pressure and systemic vascular resistance with a transient increase in the cardiac index occurred after protamine administration via the right atrium. Plasma histamine levels were significantly higher after right atrial injection. It is concluded that histamine is released as protamine traverses the lungs following right atrial injection and produces peripheral vasodilation. Possible mechanisms for histamine release are discussed.

Aged↗
PubMed1983

Common terminal repeats of the macronuclear DNA are absent from the micronuclear DNA in hypotrichous ciliate, Stylonychia pustulata.

Comparison of nucleotide sequences of a macronuclear DNA and its micronuclear counterpart of a hypotrichous ciliate, Stylonychia pustulata, demonstrates that common terminal repeats (C4A4) of the macronuclear DNA are not present at the corresponding region in the micronuclear genome. The results indicate that the common terminal C4A4 repeat is added or translocated during or after the rearrangement of the micronuclear DNA to the macronuclear DNA.

Animals↗
PubMed1983

beta-Adrenergic regulation of insulin and epidermal growth factor receptors in rat adipocytes.

Incubation of intact rat adipocytes with physiological concentrations of catecholamines inhibits the specific binding of 125I-insulin and 125I-epidermal growth factor (EGF) by 40 to 70%. Affinity labeling of the alpha subunit of the insulin receptor demonstrates that the inhibition of hormone binding is directly reflective of a specific decrease in the degree of receptor occupancy. The stereospecificity and dose dependency of the binding inhibitions are typical of a classic beta 1-adrenergic receptor response with half-maximal inhibition occurring at 10 nM R-(-)-isoproterenol. Specific alpha-adrenergic receptor agonists and beta-adrenergic receptor antagonists have no effect, while beta-adrenergic receptor antagonists block the inhibition of 125I-insulin and 125I-EGF binding to receptors induced by beta-adrenergic receptor agonists. Further, these effects are mimicked by incubation of adipocytes with dibutyryl cyclic AMP or with 3-isobutyl-1-methylxanthine. The beta-adrenergic inhibition of both 125I-insulin and 125I-EGF binding is very rapid, requiring only 10 min of isoproterenol pretreatment at 37 degrees C for a maximal effect. Removal of isoproterenol by washing the cells in the presence of alprenolol leads to complete reversal of these effects. The inhibition of 125I-EGF binding is temperature dependent whereas the inhibition of 125I-insulin binding is relatively insensitive to the temperature of isoproterenol pretreatment. Scatchard analysis of 125I-insulin and 125I-EGF binding demonstrated that the decrease of insulin receptor-binding activity may be due to a decrease in the apparent number of insulin receptors while the inhibition of EGF receptor binding can be accounted for by a decrease in apparent EGF receptor affinity. The decrease in the insulin receptor-binding activity is physiologically expressed as a dose-dependent decrease of insulin responsiveness in the adipocyte with respect to two known responses, stimulation of insulin-like growth factor II receptor binding and activation of the glucose-transport system. These results demonstrate a beta-adrenergic receptor-mediated cyclic AMP-dependent mechanism for the regulation of insulin and EGF receptors in the rat adipocyte.

3-O-Methylglucose↗
PubMed1983

Golgi, electron-microscopic and combined Golgi-electron-microscopic studies of the mitral cells in the goldfish olfactory bulb.

The local neuronal circuitry of goldfish olfactory bulb was analyzed in Golgi preparations combining light- and electron-microscopy, as well as in routinely prepared ultrastructural preparations. Mitral cells were identified with the light-microscope in Golgi-impregnated thick sections according to the following criteria: (1) cell bodies were distributed irregularly in a wide layer between 100 and 200 micrometer from the surface, (2) cell bodies were larger than other neurons (10-20 micrometer in diameter), and (3) the dendrites were directed toward the superficially-located olfactory nerve layer where they ended as highly branched glomerular tufts. These impregnated cells were examined by electron-microscopy in serial section. The results demonstrate synaptic organization in relation to the mitral cells. (1) Glomerular tufts received afferent input from primary olfactory axons which made Gray's Type I synaptic contacts. These dendrites also had reciprocal dendrodendritic synapses with dendrites of certain non-mitral cells. (2) Dendritic shafts of mitral cells made reciprocal dendritic synapses with dendrites of certain non-mitral cells. (3) Cell bodies and their initial axon segments had reciprocal synapses with certain dendrites but occurred infrequently. In reciprocal synapses, the direction of the Gray Type I (asymmetrical) is away from the mitral cell while those with Gray Type II synapses (symmetrical) are toward the mitral cell. Assuming that the type I synapse is excitatory and Type II is inhibitory, these findings explain the electrophysiological demonstration of self-inhibition discharge found in mitral cells.

Animals↗
PubMed1983

Treatment of pseudoarthrosis of the distal phalanx with the palmar midline approach.

Six patients with pseudoarthrosis of the waist of the distal phalanx were operated on with the palmar midline approach. Of these, four patients had sustained injuries of the crush type. The period between the initial injury and this surgery ranged from 2 to 10 months, averaging 4.2 months. With a midline straight incision on the pulp, bone grafting was followed by cross-pinning with Kirschner wires. All six cases obtained bony union within 6 to 11 weeks postoperatively. The operative scar was scarcely detectable and caused no problem.

Adult↗
PubMed1983

Human plasma epidermal growth factor/beta-urogastrone is associated with blood platelets.

Human epidermal growth factor (hEGF) has previously been isolated from urine and probably is identical to human beta-urogastrone (hUG). Immunoreactive hEGF/UG has been found in the plasma of normal subjects. In this study, using immunoaffinity chromatography to extract hEGF/UG from plasma, we found that immunoreactive hEGF/UG in blood was associated with blood platelets. It was present in platelet-rich, but not platelet-poor plasma and serum, and was found predominantly in the platelet fraction of whole blood. Sephadex G-50 Fine gel-exclusion chromatography of an extract of outdated blood bank platelets revealed two hEGF/UG components, one of which eluted in the void volume, and the other of which coeluted with purified standard hEGF/UG. The former hEGF/UG component was a high-molecular weight form that was cleaved into hEGF/UG by incubation with either mouse EGF/UG-associated arginine esterase or trypsin. It appeared to be identical to the high-molecular weight hEGF/UG previously reported in human urine, except for its apparently equal activities in radioimmunoassay and radioreceptor assay. The latter hEGF/UG component was immunologically, biologically, and physiochemically indistinguishable from highly purified hEGF/UG from human urine and was immunologically different from purified human platelet-derived growth factor. Platelet-associated hEGF/UG may account for the mitogenic activity of serum in cell lines in which platelet-derived growth factor is not active. Since hEGF/UG appears to be liberated from platelets during coagulation, platelet-associated EGF/UG may be involved in normal vascular and tissue repair and in the pathogenesis of atherosclerotic lesions. The discovery that the EGF/UG in plasma is associated with blood platelets raises important new possibilities for its role in human health and disease.

Blood Platelets↗
PubMed1983

Effect of mouse epidermal growth factor/urogastrone on the functional maturation of rat intestine.

Mouse epidermal growth factor/urogastrone (EGF/UG), administered sc in a dose of 0.1 microgram/g BW twice daily for 3 days, increased intestinal weight per unit length, lactase specific activity, and net calcium transport in normal 2-week-old suckling rats, but had no effect on maltase or sucrase specific activity. In normal 3-week-old weanling rats, the intestinal function of which is essentially fully mature, EGF/UG had no effect. These results suggest that EGF/UG, either secreted endogenously or ingested in breast milk, may have a role in both the morphological and functional maturation of the suckling rat intestine.

Aging↗