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Biomedical subjects

T Tsuda

Publications and source records attributed to T Tsuda.

At least 613 records · Page 34Linked to original sources
PubMed1985

[A case of acoustic neurinoma presenting as subarachnoid hemorrhage].

A case of acoustic neurinoma presenting with subarachnoid hemorrhage is reported. The patient, a 33-year-old female, had suffered from left hearing disturbance and tinnitus for several years prior to admission. She had sudden onset of severe headache in the left posterior auricular region, nausea and vomiting while watching a play-going. Immediately she was brought to a neighboring hospital by ambulance. Lumbar puncture demonstrated xanthochromic cerebrospinal fluid with high opening pressure of 380 mmH2O or more and she was diagnosed as having subarachnoid hemorrhage (SAH). As her level of consciousness was progressively lowered, she was transferred and admitted to our hospital. Findings of plain CT scan on admission suggested that she had a brainstem hemorrhage with acute obstructive hydrocephalus. After the immediate operation of ventricle drainage, she became alert. Two weeks after admission, contrast-enhanced CT scan, internal meatus tomography and vertebral angiography were performed because she complained of tinnitus and hearing loss of her left ear. A huge lt. C-P angle tumor was revealed and its total removal was carried out successfully after V-P shunt operation for her hydrocephalic condition. Histological examination showed a typical acoustic neurinoma. The postoperative course was uneventful only with a moderate facial paresis on her left side. Acute and severe subarachnoid hemorrhage of the posterior fossa in cases of acoustic neurinoma has been reported very sporadically. However, CT examination revealed such a rare case of acoustic neurinoma and lead us to a successful surgical treatment for the patient.

Adult↗
PubMed1984

Activation of protein kinase C by non-phorbol tumor promoter, mezerein.

Mezerein, classified as a second-stage tumor promoter, has no diacylglycerol-like structure in its molecule, but can activate protein kinase C both in vitro and in vivo. This non-phorbol diterpene competitively inhibits the specific binding of a radioactive tumor-promoting phorbol ester to the enzyme. It is suggestive that tumor-promoting phorbol esters and mezerein cause analogous changes in the membrane to activate protein kinase C, and utilize this protein kinase as a common receptive protein for tumor promotion.

Animals↗
PubMed1984

Influence of lesions in the limbic-hypothalamic system on insulin responses to daily repeated cold exposures in rabbits.

The effects of lesions in the basal medial hypothalamus and limbic structures on the responses in plasma levels of insulin and glucose to daily repeated cold exposure in rabbits have been investigated. The results obtained were summarized as follows: (1) The 1st cold exposure (cold exposure on the 1st day) decreased insulin levels and increased glucose levels, and these responses of insulin and glucose to cold exposure gradually decreased and then completely abolished by daily repetition of exposures in intact rabbits and each sham-operated group. (2) The lesions of periventricular arcuate nucleus (ARC), stria terminalis (ST) and dorsal fornix (FX) had no effects on the insulin responses to the 1st cold exposure, but the rates of insulin responses to the 1st cold exposure were decreased by the lesions of ventromedial hypothalamus (VMH). (3) The ARC lesions had no effects on the glucose responses to the 1st cold exposure, but the glucose responses to the 1st cold exposure were abolished by VMH lesions and were altered by lesions of ST and FX. (4) The insulin responses to cold exposure were abolished by daily repetition of exposures in rabbits with ARC lesions as same in the cases of sham-operated animals, but the insulin responses to cold exposure persisted even after daily repetition of exposures in rabbits with lesions of VMH, ST and FX different from sham-operated animals. (5) The glucose responses to cold exposure were abolished by daily repetition of exposures in rabbits with lesions of ARC and ST as same as in the cases of sham-operated animals, but the glucose responses to cold exposure persisted even after daily repetition of exposures in rabbits with FX lesions different from sham-operated animals.

Animals↗
PubMed1984

Effects of acetylcholine and short-chain fatty acids on acinar cells of the exocrine pancreas in sheep.

In order to investigate the actions of acetylcholine and short-chain fatty acids on acinar cells of the exocrine pancreas of sheep, measurements of amylase release and 45Ca efflux from superfused segments, as well as changes in membrane potential, input resistance and equilibrium potential in the acinar cells, were carried out in vitro. The application of acetylcholine or short-chain fatty acids caused a dose-dependent increase in amylase release from the superfused tissue segments. The amylase release evoked by 10(-3) M-short-chain fatty acids containing 2-8 carbon atoms increased with increasing carbon number, up to 5 (i.e. it was maximum with iso-valerate, which has 5 carbon atoms). The amylase release stimulated by acetylcholine (5.5 X 10(-6) M) or caprylate (10(-3) was accompanied by an increase in 45Ca efflux, and was significantly reduced by the removal of extracellular Ca2+. The stimulating effect of caprylate (10(-3) M) on amylase secretion was also observed in superfused segments of the guinea-pig, but not in those of the mouse, rabbit or hamster. The resting membrane potential and input resistance of acinar cells of sheep pancreas were -31.1 +/- 1.6 mV and 2.7 +/- 0.7 M omega (means +/- S.E. of means), respectively. The application of acetylcholine or short-chain fatty acids always depolarized the cell membrane and reduced the input resistance. The effect of short-chain fatty acids was observed in the presence of atropine (1.4 X 10(-6) M). The equilibrium potentials for acetylcholine and butyrate were -15.0 +/- 0.8 and -16.0 +/- 1.1 mV, respectively. It is concluded that the cellular secretory process evoked by acetylcholine is qualitatively similar to that of short-chain fatty acids, and that Ca2+ ions might be an important mediator for these secretagogues in the acinar cells of the pancreas of sheep.

Acetylcholine↗
PubMed1983

Extrachromosomal circular DNAs from murine hemopoietic tissue cells.

Extrachromosomal circular DNA complexes from cells of murine hemopoietic organs, bone marrow, thymus, spleen, and lymph nodes were examined by mica-press-adsorption method (H. Yamagishi, T. Kunisada, and T. Tsuda, 1982, Plasmid 8, 299-306). They showed wide size distribution, from 0.3 to 10 micron. The large-size DNAs of more than 1 micron (3.1 kb) in contour length were more abundant in bone marrow and thymus than they were in spleen and lymph nodes. The appearance of the large size DNAs was examined on splenocytes of athymic nude mice during ontogeny. The large-size DNAs first became detectable after 2 weeks of age and the amount increased thereafter until 9 weeks of age. It appears that large-size circular DNAs appear during differentiation from the hemopoietic stem cells into several descendent cells. Possible immunological implications for the appearance of extrachromosomal circular DNAs are discussed.

Age Factors↗