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H Yokoo

Publications and source records attributed to H Yokoo.

At least 127 records · Page 7Linked to original sources
PubMed1990

Direct evidence of conditioned fear-elicited enhancement of noradrenaline release in the rat hypothalamus assessed by intracranial microdialysis.

Inescapable footshock stress produced marked increases in noradrenaline (NA) release, which was assessed by intracranial microdialysis, in the hypothalamus of conscious rats. Emotional stress, without physical stimuli (replacement to the environment where the rats had received footshock previously), also increased hypothalamic NA release. These results suggest that foodshock stress caused increases in NA release and this activation of NA neurons appears to be reinstated simply by re-exposure to the environment previously associated with shock.

Animals↗
PubMed1990

Natural history and significance of esophageal squamous cell dysplasia.

Balloon-mesh cytologic screening for esophageal cancer done in 255 asymptomatic high-risk United States veterans (age greater than 40 years, ethanol abuse for greater than 20 years, and cigarette smoking greater than 20 pack years) identified 37 patients with squamous cell dysplasia. Of the 37 patients with dysplasia, 28 were re-evaluated prospectively at 6-month intervals for up to 36 months by balloon-mesh cytology, esophagoscopy with vital staining and biopsies, chest radiographs, oropharyngeal examination, and indirect laryngoscopy. During prospective follow-up evaluation, cytology specimens were repetitively normal in 16 patients (57%), showed inflammatory changes in eight patients (29%), persisted as dysplasia in two patients (7%) (both had endoscopic and histologic evidence of esophagitis), and progressed to carcinoma in two patients (7%) (one esophageal, one laryngeal). Although histologic findings concurred with the resolution of dysplasia, biopsy specimens were characterized by a similar difficulty in distinguishing dysplasia from inflammation. Erroneous histologic diagnoses of carcinoma in situ were made in two patients with reflux esophagitis evident endoscopically and confirmed during the course of a 24-36 month follow-up period. The authors conclude that squamous cell dysplasia detected by balloon-mesh cytology is seldom a precursor of esophageal cancer in the high-risk U.S. population but, rather, is often related to esophagitis. Thus, balloon-mesh cytology has limited use as a screening method for the early detection of esophageal cancer in the United States.

Adult↗
PubMed1990

Involvement of the cholinergic system in haloperidol-induced release of dopamine from slices of striatum in the rat.

The effects of cholinergic and anticholinergic drugs on spontaneous or haloperidol-induced release of dopamine (DA) were studied in vitro. The slices of striatum were placed in a chamber and continuously superfused with Krebs' solution, containing various concentrations of haloperidol, with or without atropine, d-tubocurarine (d-TC), tetrodotoxin (TTX), physostigmine or carbachol. Haloperidol, enhanced the release of endogenous DA from the slices of striatum at an EC50 value of 25.6 microM. The effect of haloperidol was significantly reduced by atropine (2.5 microM), while it was unaffected by d-TC (10 microM) and TTX (1 microM). In contrast, physostigmine (3.7 microM) significantly increased the haloperidol-induced efflux of DA from the slices of striatum. In addition, acetylcholine (ACh), in the presence of physostigmine or carbachol, enhanced the basal efflux of DA at EC50 values of 2.8 microM and 83 microM, respectively. The effect of ACh on the efflux of DA was antagonized by atropine. These data suggest that haloperidol-induced release of DA is, at least partially, mediated by the activation of muscarinic ACh receptors located in the striatum.

Acetylcholine↗
PubMed1990

Effects of stress, non-stress cyclicity on hypothalamic noradrenaline release in rats.

The effects of continuous stress and intermittent stress at short intervals on rat hypothalamic noradrenaline (NA) release were assessed by measuring the levels of a principal metabolite of NA, 3-methoxy-4-hydroxy-phenylethyleneglycol sulfate (MHPG-SO4) in male Wistar rats. The rats were exposed to one of five restraint stress conditions, unstressed (control), six 15 min intermittent stress periods (interspersed with 18 min non-stress periods), three 30 min intermittent stress periods (interspersed with 45 min non-stress periods), 90 min continuous stress period or 180 min continuous stress period. The 15 min intermittently stressed rats had significantly larger increases in hypothalamic MHPG-SO4 than the single 90 min and 180 min continuously stressed rats, while the 30 min intermittently stressed rats were significantly different from only the 180 min continuously stressed rats. In a comparison of the 15 min and 30 min intermittently stressed rats, which had the same total duration of stress exposure; the 15 min group had larger increases in MHPG-SO4 levels than the 30 min group. This study provides supporting evidence for the role of stress cyclicity in determining the extent of stress-induced NA release from the hypothalamus.

Animals↗
PubMed1989

Neuropeptide Y and galanin in norepinephrine release in hypothalamic slices.

Noradrenergic neurons in the locus ceruleus contain neuropeptide Y and galanin, which project to the hypothalamic region. We have investigated the regulatory mechanisms of these peptides on norepinephrine release in rat hypothalamic slices in vitro. Neuropeptide Y and galanin significantly inhibited the stimulation-evoked [3H]norepinephrine release in a dose-dependent manner (1 Hz: S2/S1 ratio (mean +/- SEM), control 0.947 +/- 0.040, n = 11, neuropeptide Y 1 x 10(-8) M 0.509 +/- 0.013, n = 8, p less than 0.01, neuropeptide Y 1 x 10(-7) M 0.283 +/- 0.021, n = 8, p less than 0.01; galanin 1 x 10(-7) M 0.448 +/- 0.026, n = 8, p less than 0.01, galanin 1 x 10(-6) M 0.261 +/- 0.023, n = 8, p less than 0.01). The inhibition of norepinephrine release by the alpha-2 agonist UK 14,304 was potentiated by neuropeptide Y and galanin. The blockade of the alpha 2-adrenergic receptors by RX 781094 diminished the inhibitory effects of neuropeptide Y and galanin on norepinephrine release. Pretreatment of hypothalamic slices with islet activating protein (a toxin that interferes with the coupling of inhibitory receptors to adenylate cyclase) attenuated the suppression of norepinephrine release by UK 14,304, neuropeptide Y, and galanin. These results support the idea that neuropeptide Y and galanin are involved in the regulation of central adrenergic transmission partially mediated by alpha 2-adrenergic receptors and islet-activating protein-sensitive guanosine triphosphate-binding proteins in rat hypothalamus.

Adenylate Cyclase Toxin↗
PubMed1989

[Tooth extraction in a case of thrombasthenia].

Thrombasthenia is a congenital platelet disorder characterized by the normal platelet count, prolonged bleedingtime, absence of platelet aggregation and defective clot retraction. Clinically, purpura, epistaxis, gingival bleeding and excessive bleeding after minor injuries or operations are the main manifestations. We experienced a case of a 15-year-old boy suffering from thrombasthenia required extraction of 6/6. The problems of nature of the disease and its familial character are described and the problems of management are outlined.

Adolescent↗
PubMed1988

Receptor reserve at striatal dopamine receptors modulating the release of [3H]dopamine.

Electrically stimulated release of [3H]dopamine [( 3H]DA) in slices of rat striatum was dose dependently inhibited by apomorphine (67% maximal inhibition) with an EC50 of 17 nM. DA receptor inactivation with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ; 0.5 and 2 mg/kg) dose dependently shifted the ED50 for apomorphine to the right and reduced the maximal inhibition obtained. Analysis of the results yielded a hyperbolic plot of receptor occupancy vs. response, indicating that a large receptor reserve (50-60%) for apomorphine exists at the DA autoreceptor in rat striatum mediating inhibition of transmitter release.

Animals↗
PubMed1988

Enhancement of dopamine release from striatal slices of rats that were subchronically treated with methamphetamine.

The effect of dopamine (DA) uptake inhibitors (methamphetamine, nomifensine, and phenylethylamine) on the release of endogenous DA from striatal slices of rats pretreated with methamphetamine (6 mg/kg/day for 9 days) was investigated. The exposure of methamphetamine-pretreated rat striatal slices to a low concentration (10(-7) M, 5 X 10(-7) M) of methamphetamine caused a greater increase in DA efflux than that of saline-treated rat striatal slices. The drug-treated rats displayed an enhanced stereotyped behavioral response to a small dose of methamphetamine (1 mg/kg). Removal of Ca2+ from the superfusion medium did not affect the difference in the rates of methamphetamine (10(-7) M) induced DA release between methamphetamine-treated and saline-treated rat striatal slices. Nomifensine- and phenylethylamine-induced DA release from striatal slices was also enhanced by repeated administration of methamphetamine. On the other hand, there was no difference in K+-induced DA release between the two groups. Moreover, repeated administration of methamphetamine caused a significant increase in 3H-dopamine uptake in rat striatal synaptosomes. These results suggest that the behavioral sensitization produced by the repeated administration of methamphetamine is accompanied by an enhancement in the release of DA induced by methamphetamine, nomifensine, and phenylethylamine in vitro and is also accompanied by increased DA uptake into striatal synaptosomes.

Animals↗
PubMed1987

The effect of neuropeptide Y (NPY) on stimulation-evoked release of [3H]norepinephrine (NE) from rat hypothalamic and cerebral cortical slices.

The effects of neuropeptide Y (NPY) on stimulation-evoked release of [3H]norepinephrine ([3H]NE) in rat hypothalamic and cerebral cortical slices were investigated. NPY inhibits the stimulation-evoked release of [3H]NE from hypothalamic, but not from cerebral cortical slices. NPY potentiates the inhibition of [3H]NE release by the alpha 2-agonist UK 14,304 in the hypothalamic slices. The blockade of alpha 2-adrenoceptors by RX 781094 diminishes the inhibitory effects of NPY. These results suggest that in the hypothalamic slices the action of NPY might be in part mediated by the alpha 2-adrenoceptors.

Adrenergic alpha-Antagonists↗
PubMed1987

Cytoskeletal alterations leading to Mallory body formation in livers of mice fed 3,5-diethoxycarbonyl-1,4-dihydrocollidine.

Cytoskeletal alterations of hepatocytes were studied in mice fed 3,5-diethoxycarbonyl-1,4-dihydrocollidine from the onset of the experiment to the time when Mallory bodies were induced, using immunofluorescent microscopy and a method which we devised in order to visualize the cytoskeletal framework of hepatocytes. The results showed that the cytoskeletal framework of the normal murine hepatocyte is composed of a network of uniformly distributed, interconnecting bundles of filaments. In the drug-fed mice, the cytoskeletal network of the hepatocytes became coarser and distorted. The Mallory body-containing hepatocytes were mostly devoid of cytoskeletal filaments, containing only a few thick bundles of filaments, which appeared partly smudgy and electron-dense. These results suggest that the formation of Mallory bodies in this animal model is associated with a marked derangement of the cytoskeletal framework, which appears to result from the progressive loss of normal filaments and the aggregation of abnormal ones.

Animals↗
PubMed1986

Ultrastructure of insulin secretory granules and insulin content of fetal pancreas exposed to ethanol in utero in the rat.

Fetal rat pancreata exposed to ethanol in utero were examined for morphometric analysis of insulin secretory granules and insulin content. The beta-cells contained both dark and light granules, and their volume density was unaltered by maternal ethanol ingestion during pregnancy. The insulin content of pancreata of newborn rats was nearly equal in control and experimental animals. The study indicates no adverse effect of maternal ethanol ingestion on fetal pancreatic insulin concentration and insulin secretory granules.

Animals↗
PubMed1985

Serial liver biopsies in psoriatic patients receiving long-term etretinate.

Twenty psoriatic patients treated with etretinate have been followed in a prospective study of liver biopsies. Twelve patients were followed up for 3 years, with four liver biopsies each. No significant damage to the liver was found during etretinate therapy. Etretinate may be stored in the fatty tissues of the liver or other body areas for prolonged periods.

Adult↗
PubMed1984

Effect of systemically administered caerulein on dopamine metabolism in rat brain.

The effect of caerulein, a cholecystokinin-like peptide, on the dopamine (DA) system was examined in rat brain. Caerulein, when tested in vitro, had no significant influence on either D-1 or D-2 DA receptors. A single injection of caerulein (400 micrograms/kg, i.p.) reduced both homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum. No significant change in DA metabolites was found in the other 7 areas (polar and medial fields of prefrontal cortex, anterior cingulate cortex, nucleus accumbens, tuberculum olfactorium, septum and amygdala). After repeated injections of caerulein (200 micrograms/kg, i.p., daily for 5 days), the decreases in striatal HVA and DOPAC had disappeared, while the amount of HVA had increased in the nucleus accumbens. These results suggest that peripherally administered caerulein modulates the nigrostriatal and mesolimbic DA neuron systems in the different modes of action.

3,4-Dihydroxyphenylacetic Acid↗