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Biomedical subjects

T Mizoguchi

Publications and source records attributed to T Mizoguchi.

At least 163 records · Page 9Linked to original sources
PubMed1985

Methods for enzymatic and colorimetric determinations of D-erythrulose (D-tetrulose).

The specific determinations of D-erythrulose by enzymatic assay or colorimetric method, which permit the quantitative determination of between 20 and 400 nmol of the sugar, are described. Enzymatic determination of D-erythrulose made use of the D-erythrulose reductase purified from beef or chicken liver, which catalyzes specifically the reduction of D-erythrulose with concomitant conversion of NADH to NAD+. The colorimetric microdetermination of erythrulose could be carried out by utilizing the phenol-sulfuric acid reaction under low temperature. These methods are simple, rapid, and sensitive, and give reproducible results.

Animals↗
PubMed1985

Characterization of an enzyme which catalyzes isomerization and epimerization of D-erythrose 4-phosphate.

The enzyme which catalyzes the conversion of D-erythrose 4-phosphate to D-erythrulose 4-phosphate and D-threose 4-phosphate has been purified to homogeneity from a crude extract of beef liver. Analysis of the purified enzyme by Sephadex G-100 gel filtration and sodium dodecyl sulfate/polyacrylamide gel electrophoresis revealed it to be a dimer of relative molecular mass 43 000. From the gas chromatography/mas spectrometry analyses of the enzymatic reaction products, it appeared that about 90% of the total amount of tetrose 4-phosphate was present as D-erythrulose 4-phosphate after equilibration. The purified enzyme, which is tentatively called 'erythrose-4-phosphate isomerase' had no significant isomerase activities on D-glyceraldehyde 3-phosphate, D-ribose 5-phosphate, D-glucose 6-phosphate and D-fructose 6-phosphate, but a strong D-ribulose-5-phosphate 3-epimerase activity was co-purified with the erythrose-4-phosphate isomerase activity through every step in the isolation. Both the erythrose-4-phosphate isomerase and D-ribulose-5-phosphate 3-epimerase activities were inactivated at the same rate at the elevated temperature, and also inhibited to the same extent by various inhibitors. It is likely, that both activities are catalyzed by the single enzyme protein.

Animals↗
PubMed1985

Release of thioltransferase from rabbit polymorphonuclear leucocytes by immune complex in vitro and inhibition of the enzyme by chloramphenicol.

Immune complex induced the release of thioltransferase from rabbit peritoneal exudates polymorphonuclear leucocytes in vitro. The release of thioltransferase occurs from viable cells and does not depend on a cytolysis. The catalytic activity of the released enzyme with S-sulfocysteine and glutathione as substrates had a distinct optimum pH at 7.6. On the contrary, opsonized zymosan was not effective as a stimulus for the liberation of thioltransferase from polymorphonuclear leucocytes. Thioltransferase liberated by the stimulation with immune complex was inhibited by chloramphenicol, but not by bacitracin. The inhibition was non-competitive (apparent Ki of 0.2 mM).

Animals↗
PubMed1985

Purification and properties of beef liver aldehyde reductase catalyzing the reduction of D-erythrose 4-phosphate.

An aldehyde reductase catalyzing the NADPH-dependent reduction of D-erythrose 4-phosphate to D-erythritol 4-phosphate was purified from beef liver. It was proved to be homogeneous by polyacrylamide gel electrophoresis, sodium dodecyl sulfate polyacrylamide gel electrophoresis and ultracentrifugation analysis. The enzyme was proved to be a monomeric enzyme and its molecular weight was about 40,000. The enzyme was able to reduce not only tetroses but also trioses, aromatic aldehydes, D-glucuronate and succinic semialdehyde. Apparent Km-values for aromatic aldehydes were lower than those for tetroses, trioses, D-glucuronate and succinic semi-aldehyde. Barbiturates and valproate were potent inhibitors of the enzyme and their apparent K1-values were in the range of 80-180 microM. Quercitrin was the most potent inhibitor and its K1-value was about 7 microM. From the viewpoint of substrate specificity and inhibitor sensitivity, it seems that the enzyme belongs to the high-Km type aldehyde reductases.

Alcohol Oxidoreductases↗
PubMed1985

Purification and some properties of rabbit liver cytosol thioltransferase.

Thioltransferase was purified 650-fold from rabbit liver by procedures including acid treatment, heat treatment, gel filtration on Sephadex G-50, column chromatography on DEAE-cellulose, isoelectric focusing (pH 3.5-10) and gel filtration on Sephadex G-75. The final enzyme preparation was almost homogeneous in polyacrylamide gel electrophoretic analysis. Only one active peak with an apparent molecular weight (Mr) of 13,000 was detected by gel filtration on Sephadex G-50 and only a single protein band with a molecular weight of 12,400 was detected by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Isoelectric focusing revealed only one enzyme species, having an isoelectric point (pI) of 5.3. The enzyme has an optimum pH about 3.0 with S-sulfocysteine and GSH as substrates. The purified enzyme utilized some disulfides including S-sulfocysteine, alpha-chymotrypsin, trypsin, bovine serum albumin, and insulin as substrates in the presence of GSH. The enzyme does not act as a protein : disulfide isomerase (the activity of which can be measured in terms of reactivation of randomly reoxidized soybean Kunitz trypsin inhibitor). The enzyme activity was inhibited by chloramphenicol, but not by bacitracin. The inhibition by chloramphenicol was non-competitive (apparent K1 of 0.5 mM). Thioltransferase activity was found in the cytosol of various rabbit tissues.

Animals↗
PubMed1984

Enzymatic isomerization and epimerization of D-erythrose 4-phosphate and its quantitative analysis by gas chromatography/mass spectrometry.

An enzyme preparation from beef liver catalyzed the isomerization and epimerization of D-erythrose 4-phosphate to D-erythrulose 4-phosphate and D-threose 4-phosphate. The presence of D-erythrulose 4-phosphate and D-threose 4-phosphate was demonstrated by several analytical methods. After dephosphorylation, the presence of D-erythrulose and D-threose was confirmed by thin-layer chromatography, gas-liquid chromatography and an enzymatic method depending upon D-erythrulose reductase. The enzymatic products were also identified and simultaneously quantitated by a new procedure using gas chromatography/mass spectrometry. Each of three tetroses was distinguished by the combination of the reduction with sodium borodeuteride and the determination of relative intensities of the ion pairs m/z 379 and 380 of sugar tetritol trifluoroacetate. By gas chromatography/mass spectrometry, we observed that D-threose 4-phosphate was also converted into D-erythrulose 4-phosphate and D-erythrose 4-phosphate. At the equilibrium, about 90% of the tetrose 4-phosphate existed in the form of D-erythrulose 4-phosphate. On the basis of gas chromatography/mass spectrometric evidence together with gas chromatographic and thin-layer chromatographic patterns, it is suggested that the single enzyme of the beef liver catalyzed both reactions of isomerization and epimerization of aldotetrose 4-phosphate.

Animals↗
PubMed1984

A rare case of early carcinoma of the gallbladder.

A 38-year-old woman was diagnosed preoperatively to have a benign polyp of the gallbladder with a delineated polypoid mass, as demonstrated with drip infusion cholangiography and ultrasonography. Cholecystectomy was performed. Postoperatively, however, this tumor proved to be an early stage carcinoma of the gallbladder. In the neck of the gallbladder, there was a protruded polypoid elastic tumor of 1.1 X 0.9 cm in width and 2.5 cm in height. The tumor was supported by a stem of 0.1 cm in diameter and 0.2 cm in height. Histopathological examination revealed a well differentiated papillotubular adenocarcinoma, which exhibited no invasion of the stem itself or its basal region. This is a rare case of early carcinoma of the gallbladder (Stage I) which grew only towards the lumen of the gallbladder cavity, and did not invade the wall. Postoperatively, cholecystectomy alone was thought to be sufficient for cure.

Adenocarcinoma↗
PubMed1984

Purification and some properties of bovine liver cytosol thioltransferase.

A cytosol thioltransferase was purified 37,000-fold from bovine liver by essentially the same procedure as reported for rat liver enzyme by Axelsson et al. [1978) Biochemistry 17, 2978-2984). The purified enzyme appears to be homogeneous on sodium dodecyl sulfate (SDS)-gel electrophoresis and has a molecular weight (Mr) of 11,000, an isoelectric point (pI) of 8.1, and an optimum pH with S-sulfocysteine and GSH as substrates of 8.5. It is specific for disulfides including L-cystine, S-sulfocysteine, ribonuclease A, trypsin, soybean kunitz trypsin inhibitor, soybean Bowman Birk trypsin inhibitor and insulin, and converts Bowman Birk trypsin inhibitor to an inactive form. The enzyme does not act as a protein : disulfide isomerase, as measured by reactivation of "scramble" ribonuclease and Kunitz soybean trypsin inhibitor. Thioltransferase activity was found in cytosol of various bovine tissues.

Animals↗
PubMed1984

Limbic kindling in the forebrain-bisected photosensitive baboon, Papio papio.

When forebrain-bisected photosensitive baboons, Papio papio, were kindled from the amygdala or hippocampus, bilateralization of convulsive seizure proved difficult, and the final stage of bisymmetrical and bisynchronous convulsive seizure unique to this species did not develop despite more than twice the number of kindling stimulations required for its development in nonbisected baboons. At the secondary site amygdala, convulsive seizure development was suppressed. Findings of the present and previous studies suggest that the corpus callosum plays: (a) a major, if not an exclusive, role in convulsive seizure bilateralization ; and (b) a critical role in the development of primarily generalized convulsive seizures unique to this epileptic baboon. Finally, in the absence of the corpus callosum (and the hippocampal commissure) the transhemisphere seizures suppressing effect generated by amygdaloid kindling appears to be mediated through the subcortical pathway which presumably exists in the brainstem.

Amygdala↗
PubMed1983

Poly-adenosine diphosphate ribose autoantibody in systemic lupus erythematosus and other related autoimmune diseases.

The binding activities of poly-adenosine diphosphate-ribose (ADPR) and ds-DNA were measured in the sera of patients with systemic lupus erythematosus (SLE) and other collagen diseases in comparison with normal subjects. High polyADPR binding activity was detected in the SLE sera. The polyADPR binding assay was as sensitive as the DNA binding assay for diagnosing SLE. In SLE sera, the increased polyADPR binding activity was correlated with that of ds-DNA and negatively with the complement (CH50) titer. With improvement of clinical symptoms of SLE, the binding activity of polyADPR decreased in parallel to the binding activity of ds-DNA and opposite to the CH50 titer. The polyADPR binding activity was occasionally high in other collagen diseases. Effects of steroid treatment of SLE on the binding activities of polyADPR and ds-DNA, and CH50 titer were examined over half a year, indicating that both binding activities are reliable parameters for judgment of the clinical course.

Adult↗
PubMed1983

New beta-lactam antibiotics, carpetimycins C and D.

Two new carbapenem antibiotics, carpetimycins C and D have been isolated from the culture broth of Streptomyces sp. KC-6643, which produced carpetimycins A and B. The structures of carpetimycins C and D have been determined to be (5R,6R)-3-[2-acetamidoethyl-(R)-sulfinyl]-6-(1-hydroxy-1-methylethyl) -7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid and (5R,6R)-3-[2-acetamidoethyl-(R)-sulfinyl]-6-(1-hydroxysulfonyloxy-1 -methylethyl)-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylic acid, respectively. Studies on the fermentation, isolation and physico-chemical properties of these antibiotics are also described.

Bacteria↗