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Biomedical subjects

Y Shibata

Publications and source records attributed to Y Shibata.

At least 703 records · Page 39Linked to original sources
PubMed1982

Inhibitory effect of vitamin E on lipoperoxide formation in rat adrenal gland.

The tissue uptake of vitamin E administered to the rats was strikingly high in the adrenal glands, and microradioautographic studies showed that the vitamin was localized morphologically in the cells of fascicular and reticular zones of the adrenal cortex, where lipofuscin pigment appears with aging. On the other hand, it was confirmed that the TBA content in rat plasma and adrenal gland was elevated following whole-body 60Co irradiation as an aging model. It was also demonstrated that the TBA content in rat adrenal markedly increased in conditions of vitamin E deficiency with and without irradiation.

Adrenal Glands↗
PubMed1981

Location of functional -SH groups in NADPH-cytochrome P-450 reductase from rabbit liver microsomes.

The total -SH content of purified NADPH-cytochrome P-450 reductase (NADPH: ferricytochrome oxidoreductase, EC 1.6.2.4) from rabbit liver microsomes accessible to an excess equivalent of PCMB was 7.0 +/- 0.3 mol thiol groups/mol protein. The modification of four -SH groups at low concentration of PCMB stimulated the activity of the enzyme. On the other hand, further blocking of -SH groups (6-7 mol -SH groups/Mol protein) with an excess amount of PCMB completely inhibited cytochrome c (or DCPI) reductase activity. The fluorescence quenching of the flavin was rapidly removed by binding of PCMB to a fifth and sixth -SH group during a gradual titration. Kinetic and fluorimetric analyses confirmed the suggestion that these two -SH groups essential for catalytic function were partly protected by NADP+ or 2'-AMP against the reaction with PCMB. Excess PCMB begins to compete with the ligand preincubated with the enzyme. The spectral perturbation on the addition of approx. 6-7 equiv. PCMB/mol enzyme is accompanied by a slight blue shift of the absorbance maximum at 380 nm, with the appearance of a pronounced shoulder at 475 nm. In contrast to the native enzyme, 3-electron-reduced semiquinone form of PCMB-treated enzyme showed the same absorption spectrum as 1-electron-reduced semiquinone which has an absorption maximum at 585 nm with a broad shoulder around 635 nm. An inhibitory effect may be attributable to the fact that NADPH is less accessible to the FAD binding site as well as the pyridine nucleotide binding site, since the rate of FAD reduction becomes extremely slow after complete modification.

Adenosine Monophosphate↗
PubMed1981

Nonsteroidal antiinflammatory agents. 2. Synthesis of 4',5-disubstituted 3-biphenylylacetic acids and their derivatives with antiinflammatory and analgesic activities.

A series of 5',5-disubstituted 3-biphenylylacetic acids (5a-n) and several alpha-methyl derivatives (5o-v) were prepared as analogues of a newly developed nonsteroidal antiinflammatory agent, 5'-chloro-5-methoxy-3-biphenylylacetic acid [1 (DKA-9), R = 4-C1Ph; R' = Me], and evaluated for antiinflammatory and analgesic activities using both carrageenan rat paw edema and AcOH writhing assays. Among them, 5-fluoro-3-biphenylylacetic acid (5m) showed the highest antiinflammatory activity, while 2-(3-biphenylyl)propionic acid (5o) showed the highest analgesic activity. However, they were less potent than 1 (R = 4-C1Ph; R' = Me) in these assays.

Analgesics↗
PubMed1981

Nonsteroidal antiinflammatory agents. 3. Synthesis of the positional isomers of 4'-chloro-5-methoxy-3-biphenylylacetic acid and their antiinflammatory and analgesic activities.

The positional isomers 3a-i of 4'-chloro-5-methoxy-3-biphenylylacetic acid [1 (DKA-9), R = 4-ClPh; R' = MeO] which is a newly developed nonsteroidal antiinflammatory agent, have been prepared and evaluated for antiinflammatory and analgesic activities using both the carrageenan-induced rat paw edema and AcOH writhing assays. The 3- and 4-biphenylylacetic acids 3a,d, which closely resemble 1 (R = 4-ClPh, R' = MeO) structurally, showed, by far, excellent activities compared with the other isomers in these assays. However, none of the compounds tested was more active than 1 (R = 4-ClPh; R' = MeO). In this series of compounds, structural requirements for good antiinflammatory activity seemed to be parallel to those for analgesic activity.

Animals↗
PubMed1981

An affinity adsorbent, 5'-adenylate-aminohexyl-sepharose. I. Purification and properties of two forms of RNase U2.

An affinity adsorbent, 5'-adenylate-aminohexyl-Sepharose 4B, was prepared by the periodate oxidation of AMp followed by coupling and condensation with amino-hexyl-Sepharose 4B. RNase U2, a purine-specific RNase, was specifically bound to this adsorbent at pH 4.5 and eluted critically at pH 5.9 in the presence of 1 M NaCl, corresponding to the pH dependence of the binding of 2'-AMP to RNase U2. By using this affinity chromatography as a main tool, a simplified and effective purification method for RNase U2 was established with a high yield of 58%. Another form of RNase U2 with low specific activity, named RNase U2-B, was eluted at a slightly higher pH from this adsorbent. RNase U2-B was indistinguishable from the original enzyme (RNase U2-A) in base specificity, affinity for ApA, molecular weight and amino acid composition, but was clearly different in specific activity, molecular activity for ApA, isoelectric point and conformation of molecule. This affinity adsorbent is also effective for the detection or isolation of small amounts of base-specific RNases in crude cell extract.

Adenosine Monophosphate↗
PubMed1981

A technique for freeze fracturing minute amounts of isolated cardiac membrane.

Electron microscopy (EM) of freeze-fractured membranes provides more information about internal membrane structure than EM of thin-sectioned or negatively stained material. However, it has heretofore been impractical to use freeze fracture routinely for analysis of highly purified membrane fractions obtainable in small (micrograms) amounts, because the technique, when conventionally applied to minute pellets, yields only one fracture of unpredictable quality; it also precludes in parallel biochemical studies by using up the entire preparation. To solve this problem, we have developed a method for freeze fracturing tiny droplets of suspended membranes containing 1-10 micrograms membrane protein, thereby allowing both multiple fractures and biochemical studies. Before fracture, the final membrane fractions can be concentrated, subjected to experimental manipulations, cross-linked, and glycerinated in a dialysis bag. The technique is illustrated on isolated gap junctions from rabbit hearts, which were chosen because their unique internal membrane structure allows unequivocal identification of membrane type based on structural criteria.

Animals↗
PubMed1981

The endocrine pancreas in pyridoxine deficient rats.

Because the supplementation of pyridoxine (vitamin B6) improves the glucose tolerance in gestational diabetes and adult onset diabetes, pyridoxine deficiency has been considered to be one of the factors that cause diabetes mellitus. We produced pyridoxine deficient rats by giving pyridoxine-free food with deoxypyridoxine which competitively the activity of pyridoxal phosphate. In these pyridoxine deficient rats plasma insulin during the glucose tolerance test was significantly low as compared with controls. In vitro experiments of pancreas perfusion showed that secretion of insulin and glucagon was impaired in the pyridoxine deficiency. Since the restriction of diet-calorie caused a decrease in arginine-induced secretion of insulin and glucagon from the isolated pancreas, the impairment of the endocrine pancreas may depend on malnutrition. Pyridoxine deficiency is surely one of the factors that impair the endocrine pancreas by multifactorial derangement of metabolism besides the tryptophan-nicotinic acid pathway.

Animals↗
PubMed1981

Isolation and characterization of an immunosuppressive acidic protein from ascitic fluids of cancer patients.

Analytical isoelectric focusing in polyacrylamide gel at pH 2.5 to pH 5 was used successfully to detect an acidic protein which can be found in large quantities in the sera of cancer patients but in only small amounts in the sera of healthy persons. The main peak of this acidic protein when obtained from cancer patients revealed a pI of 3.0, while the pI of that obtained from normal subjects was 3.1. The results obtained also demonstrated that qualitative and quantitative differences of such serum acidic proteins discriminate between sera of normal persons and cancer patients. Purification of this acidic protein (pI 3.0) was attempted with cancer ascitic fluids by successive ammonium sulfate precipitation, diethylaminoethyl cellulose column chromatography, Sephadex G-100 gel filtration, and preparative isoelectric focusing. When the purified acidic protein was characterized for physicochemical properties, it was found to have an isoelectric point of 3.0, to have a molecular weight of 50,000, and to contain 31.5% carbohydrate. Its behavior in immunodiffusion and immunoelectrophoresis was indistinguishable from that of normal human alpha 1-acid glycoprotein. However, in gel isoelectric focusing, in molecular weight, and also in carbohydrate content, the acidic protein isolated from cancer ascitic fluid differed from normal alpha 1-acid glycoprotein. Furthermore, this acidic protein was found to suppress both phytohemagglutinin-induced lymphocyte blast formation and mixed-lymphocytes reaction in vitro. The acidic protein, which we called "immunosuppressive acidic protein," and its biological activities were discussed regarding its possible role in the impairment of the immunological surveillance mechanism in the tumor-bearing host.

Ascitic Fluid↗