Search PubMed⌕ Search

Biomedical subjects

M Miyazaki

Publications and source records attributed to M Miyazaki.

At least 937 records · Page 52Linked to original sources
PubMed1983

Effects of buflomedil on isolated dog arteries.

Buflomedil (10(-6) to 10(-4) M) relaxed, in a concentration-dependent manner, helical strips of dog mesenteric, renal and femoral arteries, partially contracted due to previous exposure to noradrenaline. When partial contraction was caused by prostaglandin F2 alpha, Buflomedil produced a slight relaxation of the mesenteric and coronary arterial strips, had no effect in cerebral and femoral arteries and caused a small contraction of renal arterial strips. Buflomedil did not reduce contractions induced by submaximal concentrations of K+ in normal media and those induced by Ca++ in mesenteric arteries exposed to Ca++-free media and depolarized by excess K+. Contractile responses to transmural electrical stimulation and exogenous noradrenaline were attenuated by buflomedil; the attenuations in femoral and mesenteric arteries did not differ. Protection against persistent blockade of alpha-adrenoceptors by phenoxybenzamine was obtained by pretreatment of mesenteric arteries with buflomedil. Relaxant responses of cerebral and coronary arteries to nicotine were suppressed or abolished by buflomedil, whereas the relaxation of coronary arteries induced by tyramine was unaffected or reduced only slightly. It is concluded that buflomedil reversibly blocks alpha-adrenoceptors in arterial smooth muscle and possesses an anti-nicotinic action. As far as the concentrations used in the present study are concerned, buflomedil does not appear to interfere with the transmembrane influx of Ca++.

Animals↗
PubMed1982

High-performance liquid chromatographic determination of clioquinol and its conjugates in biological materials.

A method has been established for the determination of clioquinol (C) and its glucuronide (CG) and sulfate (CS) in biological materials. C and its internal standard were extracted with benzene-pyridine from samples. CG and CS were also hydrolyzed to C and extracted by the same method. The extracts were evaporated to dryness and redissolved in methanol. The methanol solution was subjected to HPLC using a column packed with Iatrobeads 6cp.2010 and a UV monitor (254 nm). The mobile phase was 0.1 M citric acid-methanol-n-hexane (8:86:6). The detection limit of C and 1 nmole and its recovery was above 92%.

Animals↗
PubMed1982

Regulation of rat alpha-fetoprotein production by methionine during ethionine-hepatocarcinogenesis.

The levels of serum alpha-fetoprotein (AFP) in rats were determined during hepatocarcinogenesis with ethionine, and the effects of methionine administration on serum AFP elevation in these animals were studied with the aim of investigating regulatory mechanisms of AFP was observed 6 weeks following the start of feeding a diet containing 0.25% ethionine and again at the 22nd week of feeding, when a well-differentiated hepatoma had already developed. These biphasic elevations of serum AFP concentrations in rats fed a 0.25% ethionine-containing diet decreased abruptly an significantly following a change to the basal diet either supplemented with or without 0.7% methionine. The possibility that regulation of AFP production in these rats may correlate with methionine metabolisms is discussed on the basis of the experimental data obtained.

Animals↗
PubMed1982

Effect of 3'-methyl-4-dimethylaminoazobenzene on liver cells from adult rat in primary culture.

Primary mass cultures of isolated liver cells, which prepared from normal adult rat by a collagenase-liver-perfusion technique, were treated with 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) to study the production of transformed liver cells. Enzymatically isolated liver cells had high sensitivity to 3'-Me-DAB in primary culture. By 2- or 6-day treatment, mature hepatocytes remarkably decreased in their numbers due to cytotoxic effect of 3-Me-DAB, but thereafter active proliferation of epithelial-like clear cells was observed. Six-day treatment induced epithelial-like clear cells with gross chromosomal abnormalities, although 2-day treatment failed to induce transformed cells. However, the transformed epithelial-like clear cells with chromosomal abnormalities were negative for gamma-glutamyl-transpeptidase (GGT).

Animals↗
PubMed1982

Alpha-fetoprotein dynamics during ethionine-induced hepatocarcinogenesis in rat.

Rats fed on a diet containing 0.25% DL-ethionine (ethionine), which has been usually used as carcinogenic dose, demonstrated the early elevations of serum alpha-fetoprotein (AFP) approximately in week 6 of the feedings. After declining once between week 10 and 14, the serum AFP levels increased again in week 22 of the continuous feeding, when well differentiated hepatocellular carcinoma had already developed. The level of serum AFP after development of hepatoma was found to be lower than those seen during the early elevation of AFP. Furthermore, in ethionine-induced hepatoma-bearing rats, AFP levels in the tumors were rather low as compared to those in the nontumorous portions of the liver surrounding the tumors. The results indicated that ethionine-induced hepatocellular carcinoma is not an AFP-highly-producing tumor.

Animals↗
PubMed1982

Selective growth of epithelial-like clear cells from adult rat liver by short-term exposure to glucocorticoids in primary culture.

Isolated liver cells, which were prepared from adult rats by a trypsin-liver-perfusion technique, were treated with dexamethasone or hydrocortisone at a concentration of 7.7 X 10(-6) M for 8 days in primary culture. The treated cultures displayed homogeneous population consisting of epithelial-like clear cells, while the untreated cultures displayed mixed population consisting of epithelial-like clear cells and fibroblast-like cells. The epithelial-like clear cells, which proliferated in the cultures treated with glucocorticoids for 8 days in primary culture, did not show any morphological changes following cultivation in glucocorticoid-free medium. After continuous glucocorticoid-treatment for more than 1 month, the treated cultures showed relatively low cell densities at confluence. The surface area of individual epithelial-like clear cells in the cultures treated with glucocorticoids for long periods of time was evidently greater than that in the cultures treated for only 8 days. The epithelial-like clear cells had glucose 6-phosphatase and tyrosine aminotransferase activities even though the levels of these enzyme-activities were very low compared with those in rat liver homogenates.

Animals↗
PubMed1982

Influence of methionine administration on serum alpha-fetoprotein levels in ethionine-injured rats.

Serum alpha-fetoprotein (AFP) concentrations increased promptly 2 days following a single injection of DL-ethionine (ethionine) in adult female rats. Continuous elevation of serum AFP was also observed on feeding a diet containing 1% ethionine for at least 2-3 weeks. A rise of serum AFP was not found if the diet was supplemented with 2.8% methionine. Furthermore, in rats fed on 1% ethionine for 2 weeks, dietary change to the laboratory chow supplemented with and without 2.8% methionine produced a decrease of increased serum AFP levels.

Animals↗
PubMed1982

Characteristics of gait ataxia in spinocerebellar degeneration assessed by means of simple quantitative method.

Cerebellar ataxic gait was compared with normals by a simple quantitative method. Strain gauges attached to the heel, the first and the fifth metatarsal areas of a shoe, were used and the gait was telemetrically recorded. A natural and one per second click sound-synchronized gait was analyzed. A contact sequence of the three areas of the sole, the stride time, the stance-phase time and the foot contact pattern were compared between patients and normals. All of these items disclosed different results in the two groups.

Adult↗
PubMed1982

An electronmicroscopical study on peroxidase activity of rabbit monocytes, resident and exudate macrophages.

Changes of peroxidase (PO) activity in blood monocytes, untreated or stimulated peritoneal macrophages and subcutaneous exudate macrophages of rabbits were investigated with the glucose-oxidase method in the culture experiments of these cells after their in vitro or in vivo adherence to the surface of foreign bodies. 1) PO activity was demonstrated in the nuclear envelope (NE) and rough endoplasmic reticulum (rER) in 75% of the untreated peritoneal macrophages. 2) Blood monocytes, most of the stimulated peritoneal macrophages, and subcutaneous exudate macrophages showed no PO positivity. 3) In the in vitro culture of blood monocytes and stimulated peritoneal macrophages, there appeared from 2 hours cells showing PO positivity in NE and rER. 4) Although blood monocytes, stimulated peritoneal macrophages, and subcutaneous exudate macrophages after their in vivo surface adherence showed no PO positivity, it appeared in these cells when further cultured in vitro. From the fact that such a positive change of PO activity in these cultured cells is not only a transient phenomenon but also in vitro cultural one, we cannot subscribe to the view that blood monocyte is the precursor of resident macrophages.

Animals↗
PubMed1982

Primary writing tremor treated by stereotactic selective thalamotomy.

Three cases with primary writing tremor were treated successfully by stereotactic selective thalamotomy centred mainly on the ventralis intermedius nucleus. They exhibited progressive coarse tremor of 5-7 Hz during writing, and Westphal's phenomenon on stretch, as the only neurological manifestations. Within the thalamus, a very high incidence of irregular burst discharges was recorded. These findings suggest that the writing tremor is an organic disorder.

Dominance, Cerebral↗
PubMed1982

Responses to adenine nucleotides and related compounds of isolated dog cerebral, coronary and mesenteric arteries.

In helically cut strips of dog cerebral, coronary and mesenteric arteries contracted with prostaglandin F2 alpha, adenosine, AMP, ADP, ATP and cyclic AMP produced dose-related, persistent relaxation. On the basis of ED50S, the relaxant effect seen in cerebral arteries was in the order of AMP, ADP, ATP greater than adenosine, cyclic AMP greater than aderine, dibutyryl cyclic AMP greater than inosine. On the basis of maximum relaxations, the effect was in the order of adenine, dibutyryl cyclic AMP greater than or equal to adenosine, AMP, ADP, ATP greater than cyclic AMP, inosine. The relaxant responses to adenosine, AMP, ADP, ATP and cyclic AMP were attenuated by treatment with aminophylline, whereas the relaxations induced by dibutyryl cyclic AMP, adenine and inosine were not altered. It is concluded that adenosine, AMP, ADP and ATP, but not adenine and inosine, appear to share receptors underlying arterial relaxations, and the cyclic AMP-induced relaxation does not derive from increments in cellular cyclic AMP. Treatment with aspirin did not alter the relaxant effect of ADP, adenosine and adenine, suggesting that the release of vasoactive prostaglandins is not involved.

Adenosine↗