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Biomedical subjects

N Yamaguchi

Publications and source records attributed to N Yamaguchi.

At least 829 records · Page 46Linked to original sources
PubMed1983

[Locked-in syndrome with bilateral midbrain infarcts--report of an autopsy].

A case of "Locked-in" syndrome with bilateral midbrain infarcts was reported. A 51-year-old man had a memory disturbance and a change of his personality after head trauma, and then became rapidly "Locked-in" state. He was quadriplegic and bulbar paralytic, but ocular movements were preserved. Left VAG showed the narrowing of the basilar artery and there was a striking anastomosis between the SCA and PICA. Neuropathological findings were as the following; 1) The lateral two third of bilateral cerebral peduncles were extensively infarcted. 2) There were contusion of the left frontal orbital surface and the ischemic infarction of the left frontal white matter. 3) Two small infarcted lesions were found in the ventral pons without involving the pyramidal tracts. 4) Additional findings were retrograde degeneration of the medial nucleus of the left thalamus from the left frontal orbital lesion, and were loss of the Purkinje cells and neurons of pontine nucleus from the infarction of the middle cerebellar peduncle. Tegmentum of the midbrain, pons and medulla were preserved, which was considered to be due to the anastomosis of the SCA and PICA. Bilateral midbrain infarcts are responsible lesions in this case and it seems that "Locked-in" state is not synonymous with the "Ventral pontine syndrome".

Cerebral Cortex↗
PubMed1982

Simultaneous determination of free 3-methoxy-4-hydroxymandelic acid and free 3-methoxy-4-hydroxyphenylethyleneglycol in plasma by liquid chromatography with electrochemical detection.

A new assay method is described for the simultaneous determination of free 3-methoxy-4-hydroxymandelic acid and 3-methoxy-4-hydroxyphenylethyleneglycol in plasma utilizing separation and purification by Bio-Gel P-10 followed by high-performance liquid chromatography with electrochemical detection. This technique is sensitive and reliable, and offers an inexpensive and practical alternative to gas chromatographic--mass fragmentographic methods for the monitoring of plasma levels of these catecholamine metabolites in the study of selective metabolic pathways of endogenous norepinephrine originating in the peripheral and the central nervous systems.

Adult↗
PubMed1982

Periodic urine cytology surveillance of bladder tumor incidence in dyestuff workers.

The validity of urine cytology surveillance of occupational bladder tumor incidence was evaluated by reviewing the clinical history of nine bladder tumor cases found in dyestuff plant workers. A bladder tumor surveillance system has been organized for workers (179) active and 65 retired) who had been exposed to benzidine or beta-naphthylamine in the plant. The system consists of two-stage tests: periodic urine cytology as the first-stage screening test, followed by, in suspicious cases, urological examinations as second-stage tests. The urine cytology surveillance was found to be useful for two reasons: first, it detected tumors in five out of six cases surveyed by athe system, and second, four cases screened by cytology had tumors curable by transurethral operation, while other cases underwent cystectomy. Calculated average latent periods from the first and last exposure was 26.4 years (SD = 6.0) and 14.0 years (SD = 6.2), respectively. This time period indicates that the surveillance system should continue to be used for the exposed group even after workers have ceased being exposed.

2-Naphthylamine↗
PubMed1982

Evidence supporting the existence of presynaptic alpha-adrenoceptors in the regulation of endogenous noradrenaline release upon hepatic sympathetic nerve stimulation in the dog liver in vivo.

The existence and functional significance of presynaptic alpha-adrenoceptors within the liver was investigated in anesthetized dogs. The stimulation-evoked endogenous catecholamine overflow was determined in hepatic venous blood upon hepatic nerve stimulation (12 V, 1-8 Hz, 1 min). Under resting conditions, average plasma catecholamine levels in hepatic venous and aortic blood were 0.064 ng/ml and 0.334 ng/ml, respectively. A frequency-dependent increase (P less than 0.001) was found in the hepatic venous catecholamine overflow, while aortic catecholamine levels did not change significantly at any stimulation frequency tested. The increases in catecholamine overflow were associated with decreases in hepatic arterial vascular conductance (35-66%, P less than 0.001) at all frequencies tested. Yohimbine (0.3 mg/kg, i.v.) potentiated the catecholamine overflow by 110-140% (P less than 0.05) upon stimulation at low frequencies (1-4 Hz). Clonidine (20 micrograms/kg, i.v.) inhibited the catecholamine overflow by 55-76% (P less than 0.05) at frequencies of 1 and 2 Hz, and reduced the hepatic arterial response by 46% (P less than 0.01) at 1 Hz. The pretreatment with yohimbine (0.1 mg/kg, i.v.) abolished the inhibitory effects of clonidine both on the catecholamine overflow and the hepatic arterial responses. The results support the existence of a negative feedback mechanism mediated by presynaptic alpha-adrenoceptors in the local regulation of noradrenaline release from hepatic sympathetic fibers. A functional significance of this process was suggested by an improved correlation found in the presence of clonidine between the catecholamine overflow and the hepatic arterial vascular conductance.

Animals↗
PubMed1982

Sclerosing leucoencephalopathy with membranocystic lesions of adipose tissue: a contribution to the pathology of Nasu disease.

A case of sclerosing leucoencephalopathy with membranocystic lesions of adipose tissue was reported. A 38-year-old Japanese housewife, whose parents were consanguineous, developed gradually neuropsychiatric symptoms characterized by euphoria, gait disturbance and urinary incontinence, followed by spastic tetraplegia with epileptic convulsions and died eight years later. Neuropathologically a form of sudanophilic leucodystrophy with a prominent fibrillary gliosis (dissociation glio-myelinique) associated with axonal spheroids and calcospherite depositions was revealed. A peculiar membranocystic lesion of adipose tissue was recognized not only in the bone marrow but also in other areas. However, no apparent bone pathology was observed except for a ring-like pleated lamellar structure. This case was thought to be classified as heterogeneous phenotype of membranous lipodystrophy (Nasu).

Adipose Tissue↗
PubMed1982

The monoamine oxidase and catechol-O-methyltransferase activities in the dog liver.

The activity of monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) was investigated in the liver of anesthetized dogs. The MAO activity was determined by means of the method described by Wurtman and Axelrod (1963, Biochem. Pharmacol. 12: 1439-1440) using tryptamine as a substrate. The activity of COMT was assayed with the method of Axelrod (1962, Methods in Enzymology, Vol. 5. Academic Press, New York) in the presence of epinephrine bitartrate as a substrate. The average values for the activity of MAO and COMT were found to be 57.7 nmol . min-1 . g-1 of liver and 101.8 nmol . min-1 . g-1 of liver, respectively. No significant difference in the enzyme activity was observed among various samples obtained from distinct zones (peripheral and central) and lobes at different time of sample collections. The results suggest the homogeneous distribution of MAO and COMT in the dog liver. The striking difference in the COMT activity in the dog liver as compared with that reported by others for the cat liver is probably due to a species difference between these two animals.

Animals↗
PubMed1982

Pharmacological evidence for the existence of a neuronal amine uptake mechanism in the dog liver in vivo.

The possibility of a neuronal uptake mechanism in the liver was studied in dogs anesthetized with sodium pentobarbital. Plasma catecholamine concentrations in hepatic venous blood were determined by a radioenzymatic assay following injections of tyramine (30-1000 micrograms) into either the common hepatic artery or the portal vein. Concomitant changes in hepatic vascular parameters and aortic catecholamine concentrations were also investigated. The mean basal values for hepatic venous and aortic catecholamine concentrations were found to be 0.081 +/- 0.007 ng/mL and 0.433 +/- 0.080 ng/mL, respectively. Injections of tyramine (300 and 1000 micrograms) into the hepatic artery increased hepatic venous catecholamine concentrations significantly to 0.109 +/- 0.017 ng/mL and 0.126 +/- 0.023 ng/mL (P less than 0.05, n = 7), respectively. Hepatic arterial vascular conductance decreased concomitantly by 29.7 and 44.9% (P less than 0.05, n = 7), respectively. Intraportal injections of tyramine did not bring about significant changes in either hepatic venous catecholamine concentrations or portal venous vascular conductance at any dose tested. After inhibition of monoamine oxidase with pargyline (10 mg/kg. i.v.), the effects of tyramine (1000 micrograms) injected into the hepatic artery were potentiated. The duration of action was approximately 10 min after pargyline pretreatment (control duration: 1 min). The effects of tyramine were absent after inhibition of the neuronal uptake mechanism with desipramine (1 mg/kg. i.v.). No drug tested had a significant effect on aortic catecholamine concentrations. The present results support the presence of the neuronal uptake mechanism in the dog liver.

Animals↗