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Biomedical subjects

C Tanaka

Publications and source records attributed to C Tanaka.

At least 433 records · Page 24Linked to original sources
PubMed1979

Transplantable argyrophilic gastric carcinoid of Mastomys natalensis secreting both histamine and serotonin.

A transplantable strain of gastric carcinoids of Mastomys (Praomys) natalensis secreted not only histamine but also serotonin [5-hydroxytryptamine (5-HT)]. Mastomys bearing growing transplants excreted 11.3 times more histamine and 4.4 times more 5-hydroxyindole-3-acetic acid (5-HIAA) in the urine than did Mastomys in which transplanted tumors did not grow. Mastomys that developed primary gastric carcinoids also excreted 3.9 times more histamine than did those free from primary tumors, but the difference in urinary excretion of 5-HIAA was not significant in both groups. All transplantable carcinoids contained definite amounts of both histamine and serotonin, whereas the primary gastric carcinoids contained only histamine. We also confirmed that the histamine and 5-HIAA excreted in urine increased as the size of transplanted tumors enlarged. 5-HT was histochemically demonstrated in a small number of carcinoid cells of the transplanted tumors but not in primary carcinoids.

Animals↗
PubMed1978

Enzymatic decarboxylation of L-threo-3,4-dihydroxyphenylserine in rat heart.

Decarboxylation of L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS) by the higher speed supernatant of the rat heart homogenate and the regional distribution of L-threo-DOPS decarboxylase activity were examined. Decarboxylation was demonstrated to occur specifically with L-isomer but not with D-isomer. Addition of pyrogallol was necessary for maximal recovery of norepinephrine. The optimal condition for decarboxylation of L-threo-DOPS by the rat heart enzyme was similar to conditions required with the enzymes from brain and kidney. Under the optimal conditions, Km and Vmax for L-threo-DOPS were 2.1 mM and 6.4 nmoles/mg protein/15 min, respectively. Decarboxylation of L-threo-DOPS was markedly inhibited by D-threo-DOPS and D-DOPA. The L-aromatic amino acid decarboxylase activity was highest in the right auricle followed by the atrial body, the left auricle, the right ventricle and the left ventricle.

Animals↗
PubMed1977

Morphological organization of catecholamine terminals in the diencephalon of the rhesus monkey.

The hypothalamus and thalamus of the rhesus monkey were investigated using the fluorescence histochemical method of Falck and Hillarp. The hypothalamus was found to be richly supplied with catecholamine fluorescent nerve terminals with many thick and a few varicosities, whereas nerve terminals with fine varicosities were found to be distributed over the thalamus except for the midline and medial nuclei which were innervated by nerve terminals with thicker and more intense fluorescent varicosities. The morphological characteristics and distribution pattern of catecholamine terminals were similar between the rhesus monkey and the rat. However, some species differences were noted in the suprachiasmatic nucleus, arcuate nucleus and internal layer of infundibulum in the hypothalamus. The pulvinar, which was nonexistent in the rat, had fine terminals.

Animals↗
PubMed1976

Histochemical mapping of dopamine neurons and fiber pathways in dog mesencephalon.

A topographic mapping of dopamine (DA)-containing neurons and fibers was done mainly in the mesencephalon of the dog using the fluorescent histochemical technique of Falck and Hillarp. The extensive DA neuron system was found to be located in the ventral and medial regions of the mesencephalon; the pars compacta of the substantia nigra, the area almost corresponding to the ventral tegmental area of Tsai (which consists of three groups, a caudal, the nucleus parabrachialis pigmentosus, a ventral, the nucleus paranigralis and a rostral, the caudal part of the nucleus tegmentalis ventralis of Tsai), the nucleus linearis of the raphe, and the mesencephalic reticular formation. The nigro-neostriatal projection can be traced in the non-treated or nialamide plus L-dopa treated puppies without the lesion-degeneration technique. Most fibers arising from these DA cell groups assemble at the prerubral area and ascend just dorsal to the medial forebrain bundle. Most fibers turn laterally at the lateral hypothalamus and enter the neostriatum via the dorsal part of the subthalamic nucleus, the zona incerta and the capsula interna. These findings show that the distribution of DA neurons and the nigro-neostriatal pathway are fundamentally similar to those in other mammals. In this study, the processes of the nigral and paranigral DA neurons have been demonstrated to project into the pars reticulata in the dog.

Animals↗
PubMed1976

[Inhibition of harmaline induced tremor by L-threo-3, 4-dihydroxyphenylserine, an L-norepinephrine precursor].

Effect of 3, 4-dihydroxyphenylserine (DOPS), a norepinephrine precurosr, on harmaline tremor was investigated in mice to elucidate the role of norepinephrine in the genesis of tremor. 1) Spontaneous motor activity was inhibited by L-threo-DOPS (200 mg/kg i.p.). 2) Tremor induced by harmaline (5 and 7 mg/kg i.p.) was enhanced by alpha-methyl-p-tyrosone (200 mg/kg i.p.). 3) The development and duration of tremor induced by harmaline (10 mg/kg i.p.) were inhibited significantly in a dose dependent manner by L-threo-DOPS (50, 70, 100, 150 and 200 mg/kg i.p.), but neither by D-threo-DOPS (200 mg/kg i.p.) nor DL-erythro-DOPS (200 mg/kg i.p.). 4) L-threo-DOPS (200 mg/kg i.-.) had no effect on the development of tremor induced by tremorine (5 and 10 mg/kg i.p.), while lacrimation and diarrhea caused by tremorine was markedly inhibited. 5) Administration of harmaline (10 mg/kg i.p.) produced an increase in brain 5-hydroxytryptamine content but not in that of norepinephrine. Administration of L-threo-DOPS (100 mg/kg i.p.) increased the norepinephrine content but not the 5-hydroxytryptamine content in the brain. Inhibition of harmaline tremor induced by L-threo-DOPS is attributed to the L-norepinephrine converted from L-threo-DOPS and the involvement of a noradrenergic mechanism in harmaline tremor has to be considered.

Alkaloids↗