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Biomedical subjects

S Hamano

Publications and source records attributed to S Hamano.

At least 127 records · Page 7Linked to original sources
PubMed1991

Development of the human dorsal nucleus of vagus nerve: a morphometric study.

The development of the human dorsal nucleus of the vagus nerve was studied on serial sections of the brain of 10 fetuses at 16-40 weeks of gestation, an infant at 2 months of age and an adult of 63 years. A morphometric analysis revealed that the nucleus is divided into three subnuclei (caudal, dorsal and ventral) and that this subdivision is maintained from 16 weeks of gestation to adulthood. The early development of the nucleus is gradual between 16 and 40 weeks of gestation without the rapid growth phase apparent with the motor trigeminal, hypoglossal and facial nuclei.

Brain↗
PubMed1991

Synthesis and biological evaluation of substituted benzenesulfonamides as novel potent membrane-bound phospholipase A2 inhibitors.

A novel series of 4-[N-methyl-N-[(E)-3-[4-(methylsulfonyl)phenyl]-2- propenoyl]amino]benzenesulfonamides has been prepared and evaluated as membrane-bound phospholipase A2 inhibitors. A structure-activity relationship study indicated that the optimum potency was realized with the N-(phenylalkyl)piperidine derivatives 3 and 4. These compounds inhibited the liberation of arachidonic acid from the rabbit heart membrane fraction with IC30 values of 0.028 and 0.009 microM, respectively. Several compounds (3, 4, and 28), which proved to be potent inhibitors in vitro, significantly reduced the size of myocardial infarction in coronary occluded rats by iv administrations prior to the ligation. N-(1-Benzyl-4-piperidinyl)-4-[N-methyl-N-[(E)-3-[ 4-(methylsulfonyl)phenyl]-2-propenoyl]amino]-benzenesulfonamide (3, ER-3826), which showed the protective in vivo effects at doses higher than 0.3 mg/kg iv, was finally chosen as a leading candidate.

Animals↗
PubMed1991

[Effects of low molecular weight heparin (FR-860) on the experimental disseminated intravascular coagulation models].

Effects of low molecular weight heparin (FR-860) on experimental disseminated intravascular coagulation (DIC) models in rats were compared with those of conventional unfractionated heparin (UF-heparin) and other anticoagulants. In the endotoxin-induced DIC model, FR-860 (12.5-200 U/kg/hr) and UF-heparin (25-200 U/kg/hr) inhibited dose-dependently the decreases in platelet counts, fibrinogen, antithrombin III activity and alpha 2-plasmin inhibitor activity, and they also inhibited the increases in fibrin de-products and thrombus formation in the glomerular capillary bed. Neither gabexate mesilate (FOY, 10 mg/kg/hr) nor nafamostat mesilate (FUT, 0.1 mg/kg/hr) improved endotoxin-induced DIC. FR-860 showed comparable potency to UF-heparin in plasma anti-factor Xa (F.Xa) activity. However, FR-860 was weaker than UF-heparin in prolongation of activated partial thromboplastin time. In the thrombin-induced DIC model, both FR-860 and UF-heparin significantly improved, as seen in the endotoxin-induced DIC model, the changes in coagulation and fibrinolytic parameters and suppressed the production of pulmonary thrombus. On the other hand, both FOY and FUT showed significant but weak improvement in this model. In addition, FR-860 inhibited the enhancement of fibrinolysis and the production of pulmonary thrombus in the lactic acid-induced DIC model. These results suggest that the efficacy of FR-860 on DIC in rats is comparable to that of UF-heparin and that the efficacy can be attributed to its anti-F.Xa activity. FR-860 can be expected to be a useful therapeutic drug for DIC.

Animals↗
PubMed1991

Pharmacological study on Ba2(+)-stimulated catecholamine secretion from cultured bovine adrenal chromaffin cells: possible relation of Ba2+ action to Ca(2+)-activated secretory mechanism.

The stimulatory action of Ba2+ on catecholamine secretion from cultured bovine adrenal chromaffin cells was studied to elucidate a possible relationship between Ba2+ action and the Ca2(+)-mediated secretory mechanism. Catecholamine secretion was dramatically stimulated by Ba2+ in the absence of external Ca2+, and this stimulatory action was observed in a concentration-dependent manner. Ba2+ evoked the concomitant release of dopamine beta-hydroxylase in a similar manner to the Ca2(+)-dependent secretion. The stimulation of catecholamine secretion by low concentrations of Ba2+ was markedly inhibited by protein kinase inhibitors, polymyxin B and trifluoperazine (TFP). The inhibitory action of polymyxin B, but not that of TFP, on the Ba2+ action was attenuated by elevating the concentration of Ba2+ in the incubation mixture. The stimulatory action of Ba2+ was enhanced by a protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). In contrast to the acute effect of TPA, chronic exposure of chromaffin cells to high concentration of TPA reduced catecholamine secretion stimulated by Ba2+ as well as high K+ and carbamylcholine. These findings suggest the possibility that Ba2+ may activate Ca2(+)-mediated secretory processes presumably through its action on protein kinase C, thus resulting in the stimulation of catecholamine secretion from bovine adrenal chromaffin cells.

Adrenal Medulla↗
PubMed1991

Radical cranio-orbital reconstructive procedures for cloverleaf skull deformity in adult: operative technique for the longest survivor--case report.

Cosmetic cranio-orbital reconstructive surgery was carried out on a 22-year-old male, the longest surviving case of cloverleaf skull syndrome reported. He previously underwent classical linear suturectomy for synostotic sutures and temporal cranioplasty. Fortunately, hydrocephalus became arrested so did not require continuous cerebrospinal fluid drainage through shunt tube. His intelligence quotient was in the 40s. The present problem was mainly of cosmetic cranio-orbital corrections of shallow orbits with resultant exophthalmos, frontal dysgenesis, and marked temporal bossings. Bilateral orbital advance, lateral canthal/pterional reshaping, frontal remodeling, and temporal reduction cranioplasty were performed. The postoperative outcome was satisfactory. The cloverleaf skull deformity is etiologically and pathologically heterogeneous, so radical surgical reconstructive procedures should be planned and designed individually.

Adult↗
PubMed1991

Hydromyelic hydrocephalus. Correlation of hydromyelia with various stages of hydrocephalus in postshunt isolated compartments.

The clinical features and pathophysiology of specific forms of hydromyelia are analyzed in this report together with the chronological changes of associated hydrocephalus. Nine patients were studied; all had hydromyelia with varying degrees of associated hydrocephalus. Clinically applicable classification systems were used to evaluate the progression of hydrocephalus (Stages I to IV) and to define the compartment isolated after shunting in the previously communicating cerebral ventricles (Types I to IV). Four patients had Stage IV disease (holoneural canal dilatation); one had Stage II and four had Stage I disease (both Stages I and II with supratentorial hydrocephalus). All patients were initially treated by ventriculoperitoneal shunting at an average age of 9.9 years. Five patients had progressive spinal symptoms before or after treatment of their hydrocephalus. Two patients had Type III isolation (an isolated rhombencephalic ventricle) with a functioning ventricular shunt; ventriculography confirmed a communication between the fourth ventricle and the hydromyelia, and both patients improved after placement of a shunt in the fourth ventricle. The remaining patients had Type IV isolation (isolated central canal dilatation) with a functioning ventricular shunt. This study indicates that in some cases the pathophysiology of hydromyelia is closely related to associated hydrocephalus. A new concept of the development of an isolated compartment after shunting is proposed to explain the progression of hydromyelia in these cases.

Adolescent↗
PubMed1991

Tetrodotoxin-insensitive Na+ channel activator palytoxin inhibits tyrosine uptake into cultured bovine adrenal chromaffin cells.

The effects of the tetrodotoxin-insensitive Na+ channel activator palytoxin on both the secretion of endogenous catecholamines and the formation of 14C-catecholamines from [14C]tyrosine were examined using cultured bovine adrenal chromaffin cells. Palytoxin was shown to cause the stimulation of catecholamine secretion in a concentration-dependent manner. However, this toxin caused the reduction rather than the stimulation of 14C-catecholamine formation at the same concentrations. Palytoxin failed to cause any alteration in the activity of tyrosine hydroxylase prepared from bovine adrenal medulla. Furthermore, the uptake of [14C]tyrosine into the cells was shown to be inhibited by this toxin under the conditions in which the suppression of 14C-catecholamine formation was observed, and this inhibitory action on tyrosine uptake was closely correlated with that on catecholamine formation. The inhibitory action of palytoxin on tyrosine uptake into the cells was observed to be noncompetitive, and this effect was not altered by the removal of Na+ from the incubation mixture. These results suggest that palytoxin may be able to inhibit the uptake of [14C]tyrosine into the cells, resulting in the suppression of 14C-catecholamine formation, probably through its direct action on the plasma membranes of bovine adrenal chromaffin cells.

Acrylamides↗
PubMed1991

Pharmacokinetics of a novel dopamine DA1 receptor agonist, E4101, and an improvement of its bioavailability in dogs.

Pharmacokinetic parameters of E4101,(-)-(3R,4R)-3-(2-chloro-3-hydroxyphenyl)- 4-(3,4-dihydroxyphenyl)-pyrrolidine hydrochloride, in plasma were determined in conscious beagles. E4101 was extracted from plasma using a Bond Elute C18 cartridge and determined by HPLC connected to a reverse phase ODS column and an electrochemical detector. After an i.v. administration of 1 mg/kg, the plasma level of E4101 decreased according to the three compartment model. The half lives of the alpha, beta and gamma phases were 1.3, 8.1 and 27 min, respectively. The mean residence time (MRT) and total clearance were 14.5 min and 78 ml/min/kg, respectively. When 3 mg/kg of E4101 were administered orally under fasting, E4101 in plasma reached the peak (Cmax: 22.4 ng/ml) 45 min after administration. The bioavailability was 3.6%. When 3 mg/kg of E4101 in combination with 15 mg/kg of ascorbic acid was orally administered in capsule, the area under concentration curve (AUC) was increased 7-fold compared with that in a matched control study. A combination with 15 mg/kg of tartaric acid, citric acid, L-aspartic acid or L-cysteine also increased the AUC, byt they were less effective than ascorbic acid. When 10 mg/kg of E4101 in combination with 25 mg/kg of ascorbic acid as a sustained-release dosage form using oily somisolid matrix orally administered to non-fasted beagles, the duration of effective plasma concentration (2 ng/ml plasma in i.d. administration) was 8.4 +/- 1.0 hr (mean +/- SE, n-4). The Cmax was 16.2 +/- 2.5 ng/ml.

Animals↗
PubMed1991

[Crossed cerebellar diaschisis demonstrated by SPECT in hemiplegic children].

Crossed cerebellar diaschisis (CCD) in twenty five children with hemiplegia were studied using single photon emission computed tomography (SPECT) with N-isopropyl-p-I-123-iodoamphetamine. Seven of twenty-five patients had cerebral palsy, and the others were impaired by acquired brain injury between ten months and fourteen years of age. CCD was demonstrated in five patients (20%), who were impaired by acquired brain injury after seven years of age. CCD could never be detected in patients with cerebral palsy. Ipsilateral cerebellar diaschisis was also demonstrated in two patients with cerebral palsy and three with early acquired brain injury before three years of age. It is suggested that diaschisis presents itself as a different form in a contralateral and ipsilateral cerebellum before three years of age from a form which presents after seven years of age.

Adolescent↗
PubMed1991

[A case of acute polyradiculoneuritis associated with autonomic involvement of the pupils].

Acute polyradiculoneuritis relapses rarely, and autonomic nerve involvement is less frequent than motor cranial nerve involvement. An 11-year-old boy exhibited acute relapsing polyradiculoneuritis associated with two types of autonomic dysfunction of pupils 6 months after the onset of the disease. Parasympathetic dysfunction of pupils with ocular palsies preceded neuropathy of limbs at the onset. Thereafter, sympathetic dysfunction of pupils without ocular palsies was revealed by pupillography at the 2nd attack of limb palsies.

Autonomic Nervous System Diseases↗
PubMed1990

Stimulatory actions of bioflavonoids on tyrosine uptake into cultured bovine adrenal chromaffin cells.

The effects of flavonoids on L-[14C]tyrosine uptake into cultured adrenal chromaffin cells were examined. Flavone markedly stimulated tyrosine uptake into these cells in a manner dependent on its concentration. Apigenin also caused a moderate stimulatory action, but quercetin had no significant effect on the uptake. Flavone also stimulated the uptake of histidine, but did not affect the uptake of serine, lysine, or glutamic acid. These results are considered to propose the possibility that flavonoids may be able to stimulate the precursor uptake into the cells, resulting in an enhancement of the biogenic amine production.

Adrenal Medulla↗
PubMed1990

Effect of a thromboxane A2 synthetase inhibitor (OKY-046.HCl) on airway hyperresponsiveness in guinea pigs.

We studied the effect of (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoic acid hydrochloride monohydrate (OKY-046.HCl), a specific thromboxane (TX) A2 synthetase inhibitor, on airway hyperresponsiveness of guinea pigs. OKY-046.HCl (30-100 mg/kg, intraduodenally (i.d.) or orally (p.o.)) suppressed dose dependently the airway hyperresponsiveness to acetylcholine (ACh) induced by formyl-methionyl-leucyl-phenylalanine (FMLP), platelet activating factor (PAF) and repetitive antigen. OKY-046.HCl (100 mg/kg) also inhibited the increase in TXB2 in bronchoalveolar lavage fluid (BALF) induced by FMLP, PAF and antigen. Aspirin 10 or 30 mg/kg i.d. or p.o.) suppressed the airway hyperresponsiveness induced by FMLP and PAF but not by antigen. Azelastine (10 mg/kg i.d.) was ineffective on PAF- and antigen-induced airway hyperresponsiveness. TXA2 mimetic drugs caused airway hyperresponsiveness that was not inhibited by OKY-046.HCl (30 mg/kg i.v.). Furthermore, OKY-046.HCl showed no effect on propranolol- and physostigmine-induced airway hyperresponsiveness which did not accompany TXB2 generation in BALF. The number of eosinophils in BALF increased after FMLP exposure, an effect which was not inhibited by OKY-046.HCl. These results suggest that OKY-046.HCl inhibits airway hyperresponsiveness by suppressing TXA2 generation. We suggest that OKY-046.HCl will be a new antiasthmatic drug.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

The finite element analysis of brain oedema associated with intracranial meningiomas.

The mathematical model of vasogenic brain oedema, which was presented at the previous meeting in 1987, was applied to the analysis of peritumoural brain oedema associated with meningiomas. Magnetic resonance images of 90 patients with intracranial meningiomas were reviewed to analyze the spatial extension of peritumoural brain oedema. It is assumed that the heterogeneous pattern of distribution of peritumoural oedema reflects the variability of the compact density of the fibers in the white matter. A two dimensional finite element model was constructed with 786 triangular elements from a horizontal section of the human brain. The development of oedema, the change of interstitial pressure, the deformation of the brain and the absorption of oedema fluid could be simulated by the finite element method. The result of computer simulation represented interactive behaviour of the brain tissue, extracellular fluid, and cerebrospinal fluid in the clinical situation. The finite element method (FEM) may provide a new experimental tool to analyze the pathophysiology of vasogenic brain oedema.

Brain↗
PubMed1990

Enhancement by cytochalasin B of ouabain-stimulated catecholamine secretion from cultured bovine adrenal chromaffin cells: possible relation to alteration in Na+/K(+)-pump activity.

1. Catecholamine secretion evoked by ouabain from cultured bovine adrenal chromaffin cells has previously been shown to be markedly enhanced by pretreatment of the cells with cytochalasin B (Morita et al., 1988). To elucidate a possible mechanism of this enhancement, the stimulatory action of ouabain on Ca2+ influx as well as catecholamine secretion was then examined in the cells pretreated with or without cytochalasin B. The effect of cytochalasin B pretreatment on the inhibitory action of ouabain on the Na+/K+ pump was also examined by measuring 86Rb+ uptake into the cells. 2. Pretreatment of the cells with cytochalasin B caused enhancement of ouabain-induced catecholamine secretion, and this enhancement was accompanied by the elevation of ouabain-stimulated 45Ca2+ uptake into the cells. The inhibitory action of ouabain on 86Rb+ uptake was significantly enhanced by pretreatment of the cells with cytochalasin B under the same conditions. 3. These results indicate that the enhancement of ouabain-induced catecholamine secretion caused by cytochalasin B pretreatment may be due to the increase in ouabain-stimulated Ca2+ influx into the cells and, furthermore, suggest the possibility that this increase in Ca2+ influx may be attributed to the potentiation of the inhibitory action of ouabain on the Na+/K+ pump in the adrenal chromaffin cell. Thus, the present study provides an evidence for a possible role of microfilaments as one of the intrinsic factors modulating the plasma membrane functions.

Adrenal Medulla↗
PubMed1990

Development of the human mesencephalic trigeminal nucleus: a morphometric study.

Anatomical development of the human mesencephalic trigeminal nucleus was assessed quantitatively and qualitatively, using serial sections of brains, with the help of a computer-assisted image-analyser. Five fetuses at 16, 18, 21, 23 and 27 weeks of gestation; five neonates at 30, 32, 33, 35 and 40 weeks of gestation; a two-month-old infant and a 63-year-old adult were studied. Morphometric analyses of the mesencephalic trigeminal nucleus revealed that orocaudal columnar length and neuronal areas gradually increased with gestational age. Diversity of neuronal areas appeared after 32 weeks of gestation, but neuronal numbers and shapes showed little change throughout prenatal and postnatal life.

Cell Count↗
PubMed1990

[Anti-allergic effects of (E)-3-[p-(1H-imidazol-1-lylmethyl) phenyl]-2-propenoic acid (OKY-046), a specific thromboxane (TX) A2 synthetase inhibitor: effects on type I allergic reactions].

We studied the effects of OKY-046 on type I allergic reactions. OKY-046 (100 mg/kg) given orally suppressed antigen-induced bronchoconstriction and TXB2 generation in broncho alveolar lavage fluid in rats passively sensitized with anti-DNP-As monoclonal IgE. At the dose of 30 mg/kg given intraduodenally, it also inhibited antigen-induced bronchoconstriction in guinea pigs passively sensitized with anti DNP-As serum and actively sensitized with ovalbumin. However, aspirin (30 mg/kg) didn't suppressed them significantly. Azelastine (10 mg/kg) inhibited bronchoconstriction in passively sensitized rats and actively sensitized guinea pigs. In 48 hour homologous PCA reactions of rats and mice, oral administration of OKY-046 (300 mg/kg) and tranilast (100 mg/kg) suppressed the extravasated dye in the skin. OKY-046 decreased histamine release from passively sensitized rat peritoneal exudate cells. There was no effect of OKY-046 on SRS-A and leukotriene release from actively sensitized guinea pig lungs and passively sensitized rats. In conclusion, we think that OKY-046 should be an useful asthmatic drug or anti-allergic drug by oral administration.

Acrylates↗
PubMed1990

[Anti-allergic effects of (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoic acid (OKY-046), a specific thromboxane (TX) A2 synthetase inhibitor: effect of OKY-046 on II-IV type allergic reactions].

We studied the effects of OKY-046 on types II, III and IV allergic reactions, as classified by Coombs and Gell. In Type II, OKY-046 at 30-100 mg/kg intraduodenally (i.d.) and at 1-30 mg/kg intravenously (i.v.) inhibited the bronchoconstriction in a dose-dependent manner after Forssman antigen injection. Aspirin (3 mg/kg, i.v.) also suppressed it. OKY-046 (30-100 mg/kg, i.d.) suppressed the increase of TXB2 level in the plasma in a dose-dependent manner. However, there was no effect of OKY-046 and aspirin on the decrease in complement activity (CH50), platelets and leukocytes. Additionally, OKY-046 (300 mg/kg, p.o.) prolonged the survival time following Forssman antigen injection. However, the immune hemolysis reaction was not prevented by OKY-046 (10(-6)-10(-3) M). FUT-175 protected against the Forssman shock at 1 mg/kg, i.v. and the in vitro immune hemolysis reaction at 10(-5) M. In Type III, OKY-046 (300 mg/kg, p.o.) significantly suppressed the direct passive Arthus reaction and immune complex nephritis in rats. There was no effect of OKY-046 on the delayed-type hypersensitive response to picryl chloride in mice. We think that OKY-046 should be a beneficial drug for the treatment of types II and III allergic reactions.

Acrylates↗