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Biomedical subjects

M Miyazaki

Publications and source records attributed to M Miyazaki.

At least 883 records · Page 49Linked to original sources
PubMed1984

Preparation and primary culture of liver cells isolated from adult rats by dispase perfusion.

The dispase perfusion technique was used to isolate liver cells from adult rats. The optimum conditions for obtaining many isolated liver cells with high viability were an enzyme concentration of 2000 U/ml, a pH of 7.5 and a perfusion time of 20 min. The population of isolated liver cells prepared with dispase consisted of 43.6% cells with diameters less than 20 micron and 56.4% cells with diameters above 20 micron. The isolated liver cells were cultured in basal culture medium either supplemented with or without dexamethasone (1 X 10(-5)M) and insulin (10 micrograms/ml). The addition of hormones to the culture medium improved the attachment efficiency of the isolated liver cells and delayed the disappearance of mature hepatocytes. Epithelial-like clear cells proliferated early in primary culture even in the presence of hormones. Therefore, functioning mature hepatocytes and proliferating epithelial-like clear cells coexisted well in the hormone-containing medium. Furthermore, the number of cultured cells reached a maximal level earlier in the presence of hormones than in the absence of hormones. The level of TAT activity in primary cultured cells was higher up to 3 days after inoculation in the presence of hormones than in their absence. No difference between G6Pase activity in primary cultured cells in the presence of hormones and that in the absence of hormones was found.

Animals↗
PubMed1984

Effect of high-protein diet on liver alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase in rats.

In tryptophan-niacin metabolism, alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) [EC 4.1.1.45] is known to play an important role by catalyzing the decarboxylation of alpha-amino-beta-carboxymuconate-epsilon-semialdehyde, a metabolite of tryptophan which cyclizes spontaneously to form quinolinate. In this study, we investigated the effect of either dietary protein or amino acids on the activity of ACMSD in rats. When rats were fed on a high-protein diet ad libitum for several days, their liver ACMSD activity was greatly increased. Kidney ACMSD activity was also slightly elevated by a high-protein diet. Tryptophan, a precursor of the substrate of ACMSD, was not responsible for the increase of ACMSD activity caused by high-protein diet. On the contrary, insufficiency of dietary tryptophan rather elevated ACMSD activity. The increased amount of amino acids other than tryptophan in the diet resulted in the elevation of liver and kidney ACMSD activities. Although the increase of essential amino acids in the diet slightly elevated the liver ACMSD activity, the enzyme activity was enhanced markedly by feeding the diet containing both essential and nonessential amino acids in high concentrations. These results indicate that at least several amino acids, including some essential and nonessential ones, are responsible for the elevation of ACMSD activity which is induced by high-protein diet. Since liver ACMSD activity in adrenalectomized rats was also increased by feeding a high-protein diet, adrenocortical hormone was thought to be unnecessary for such enzyme induction.

Amino Acids↗
PubMed1984

Evidence for a putatively new angiotensin II-generating enzyme in the vascular wall.

An inhibitor of angiotensin I (ANG I) converting enzyme, SA446, reduced the response to ANG I of blood vessels isolated from dogs and monkeys, but did not abolish the response even at high concentrations. The residual action of ANG I in the presence of high concentrations of SA446 could be abolished by (Sar1, Ala8)-ANG II. Vascular strips and crude extracts of vessels and lungs possessed the enzymic activity generating ANG II from ANG I, or hippuric acid from hippuryl-histidyl-leucine (HHL). The HHL-hydrolysing activity of the crude extracts was completely inhibited by SA446 (10(-7) mol/l) and/or Na2-EDTA (10(-3) mol/l). However, the octapeptide generation was not abolished despite the combined treatment with SA446 (5 X 10(-4) mol/l) and Na2-EDTA (5 x 10(-3) mol/l). The residual activity forming ANG II was inhibited by chymostatin and soybean trypsin inhibitor, which however did not affect the HHL-hydrolysis. Combined treatment with SA446 (10(-5) mol/l) and chymostatin (2.5 X 10(-5) mol/l) abolished the vascular action of ANG I but did not alter the action of ANG II. These results strongly suggest that besides the ANG I converting enzyme, another enzyme which generates ANG II is present in vascular tissues and lungs, and may play an important role in the local generation of ANG II, which possibly regulates the regional vascular tone.

3-Mercaptopropionic Acid↗
PubMed1984

Phenotypical stability of a human hepatoma cell line, HuH-7, in long-term culture with chemically defined medium.

A chemically defined medium containing selenium was further improved, and the improved medium showed excellent ability to support growth and colony formation of a human hepatoma cell line, HuH-7. The improved defined medium (designated as IS-RPMI) contained small amounts of unsaturated fatty acids, inorganic trace elements including selenium, and HEPES buffer. Many of these additions exert only a small individual effect on the growth of cells, but their cumulative effects were substantial. HuH-7 cells replicated continuously with a doubling time of 47-51 hr in IS-RPMI. A conditioned medium from a semiconfluent population increased the colony-forming ability of HuH-7 cells in IS-RPMI. The addition of insulin to the medium gave good colony growth, thus duplicating the effect of the conditioned medium. Although some alterations of morphological and growth characteristics of HuH-7 cells were observed, the differentiated liver functions, as revealed by production of plasma proteins including high levels of alpha 1-fetoprotein, were maintained for a period of more than 3 years and through 70 passages under the above culture conditions.

Animals↗
PubMed1984

[Tubular dysfunction after open heart surgery].

beta 2-microglobulin (BMG) and conventional renal function parameters (creatinine clearance (C-cr) etc.) were measured in 36 adult patients before and after open heart surgery (Group-2). Same study was performed in 14 adult patients abdominal surgery (Group-1). Urinary BMG concentration (U-BMG) increased remarkably in both groups immediately after surgery. U-BMG returned to the preoperative level on the 4th postoperative day (4-POD) in Group-1, and 7-POD in Group-2. The degree of increase in Group-2 was remarkable comparing with that in Group-1. The tubular dysfunction after surgery was believed to result in a marked rise in U-BMG, therefore, the later recovery and higher increase of U-BMG in Group-2 indicated that the tubular dysfunction after open heart surgery was severer comparing with that after abdominal surgery. On 7-POD, in Group-2, U-BMG was still abnormal in 13 cases, which suggested the prolonged tubular dysfunction after open heart surgery. A retrospective study to determine the risk factors of prolonged tubular dysfunction was performed in 34 patients in Group-2. Significant risk factors were preoperative blood urea nitrogen and urine osmolarity. Several factors were not significant including perfusion time, aortic alamp time, preoperative C-cr, U-BMG, serum creatinine concentration and free water clearance.

Acute Kidney Injury↗
PubMed1984

[Preclinical studies of intra-arterial chemotherapy using mitomycin C microspheres].

Heated albumin microspheres 45 +/- 8 microns dia. containing 5% mitomycin C were infused into rabbit femoral artery to assess the depot effects. MMC levels were measured in the muscle and VX -2 tumor tissues fed by the femoral artery as well as in the drainage vein blood. Furthermore, the histologic changes in the VX -2 tumor and the MMC microspheres entrapped in the arterioles were surveyed microscopically. Drug concentration in the case of MMC microspheres was maintained at high levels in both tissue and venous blood over 4 hours, but in the rabbits infused conventional MMC, drug levels decreased below the assay limitation 2 hours after injection. The microscopic findings 2 weeks later revealed necrotic VX -2 tumor tissue as well as the MMC microspheres remaining in the arterioles .

Animals↗