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Biomedical subjects

K Ushio

Publications and source records attributed to K Ushio.

At least 109 records · Page 6Linked to original sources
PubMed1981

Erythrocyte factors concerned in the inhibition of ALA-D by lead.

Erythrocyte factors are concerned in the inhibition of delta-aminolaevulinic acid dehydratase (ALA-D) by lead at 20 to 100 nM concentrations. The activity of the factors in detected in Hb fractions from Sephadex G-200 gel filtration of erythrocyte supernatant. After gel filtration of erythrocyte supernatant from a lead worker, 50% of lead is found in ALA-D fractions, although the fractions recover from ALA-D inhibition. The recovered activity is reinhibited if the enzyme fraction is preincubated with Hb fraction obtained from the same chromatography. Similarly obtained enzyme from a normal subject is also inhibited when it is preincubated with normal Hb fraction and lead acetate at 20 to 100 nM concentrations. The extent of the inhibition depends on the concentrations of Hb fraction and lead acetate preincubated. Reinhibition of lead worker enzyme with normal Hb fraction may be deleted not only by heating but also by zinc or DTT as well. Hb fraction heated at 60 degrees C for 5 min is also able to induce the lead-inhibition of the activity in ALA-D fraction. Half life of the factors is 26 min at 60 degrees C and 3 min at 80 degrees C.

Chromatography, Agarose↗
PubMed1981

[A modified FEP (free erythrocyte protoporphyrin) test (author's transl)].

In order to simplify FEP (free erythrocyte protoporphyrin) test, we studied on the Piomelli's method, specially on the preparation of standard solution and on the role of celite-saline. N,N-dimethylformamide (DMFA) was used as the solvent of protoporphyrin standard (protoporphyrin IX dimethylester, Sigma Chemical Co.). The stock solution was stable for over 6 months at 4 degrees C. To examine the recovery and extraction efficiency, the stock solution (PP) diluted with DMFA was also added to blood. Ten microliter of DMFA added to 40 microliter blood had no effect on the FEP extraction. In the absence or at low concentrations of protein components, fluorescence intensity of added protoporphyrin extremely decreased in the extract with celite-saline. It seems to be due to the adsorption of protoporphyrin to celite. In the presence of proteins, there was no difference between fluorescence intensity of protoporphyrin with celite-saline dilution extraction and that with distilled water dilution extraction. The FEP levels in 128 lead workers (blood lead levels, 4.9-80.8 micrograms/100 g) with celite-saline extraction were almost the same as with distilled water dilution extraction. Thus celite-saline dilution was able to be displaced by the distilled water dilution, and the extraction procedure was slightly simplified. With our method, the average recovery was 93% and extraction efficiency was 80-90%.

Dimethylformamide↗
PubMed1980

Restoration of lead-inhibited 5-aminolevulinate dehydratase activity in whole blood by heat, zinc ion, and (or) dithiothreitol.

We examined effects of heat, zinc, ion, and dithiothreitol in restoring the activity of lead-inhibited-5-aminolevulinate dehydratase (EC 4.2.1.24). The ratio of non-activated to activated activity produced by dithiothreitol correlated well with blood lead concentration among 35 lead workers. The individual effects of heat, zinc, or dithiothreitol differ from each other in the shift of pH optimum as well as in the extent to which activity is restored. Dual or triple combinations of these agents show additive or complementary restoration of activity. The combination of heat and zinc or zinc and dithiothreitol expands the range of optimum concentration of zinc in restoring activity. Using these combinations of agents, we can expect more accurate evaluation of lead exposure than by measuring only activation of zinc. Although dithiothreitol most powerfully restores activity, it restores not only the activity inhibited by lead exposure but also the activity removed by oxidation of SH-groups in the enzyme molecule.

Dithiothreitol↗
PubMed1980

Chemotherapeutic study on canine gastric cancer induced by N-ethyl-N'-nitro-N-nitrosoguanidine.

Studies were made on the chemotherapy of gastric cancer in dogs induced by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG). Four male Beagle dogs were given a solution of ENNG at 100 approximately 150 microgram/ml with or without 0.4% Tween 60 to drink for 5 approximately 8 months. They all developed gastric adenocarcinomas, which were confirmed by histological examination of biopsy specimens taken in months 13 approximately 32 of the experiment. After confirming the presence of gastric cancer, 1-n-hexylcarbamoyl-5-fluorouracil (HCFU), a derivative of 5-fluorouracil, was given to the dogs orally as capsules at a daily dose of 5 or 10 mg/kg body weight. One dog died from adverse effects of HCFU 12 days after the beginning of chemotherapy. The other 3 dogs were treated with CHFU for 82 approximately 424 days. In these dogs, the tumor size, measured by X-ray examination, increased during chemotherapy. On autopsy, the tumors in the stomach were found to be restricted to the antrum, and metastases of the gastric adenocarcinomas to the regional lymph nodes and/or liver were found in 2 dogs. No degenerative changes of tumor cells were found in the stomach or metastasized organs, except for necrosis of cells in a perigastric regional lymph node of the dog. The value of using canine gastric cancer in studies on chemotherapy is discussed.

Adenocarcinoma↗
PubMed1977

Studies on the mechanism of the adenosylcobalamin-dependent diol dehydrase reaction by the use of analogs of the coenzyme.

A series of 16 analogs of 5'-deoxy-5'-adenosylcobalamin (adenosylcobalamin) were examined for their effects on the diol dehydrase system of Klebsiella pneumoniae (Aerobacter Aerogenes). Four analogs, ara-adenosyl-, aristeromycyl-, 3-isoadenosyl-, and nebularylcobalamin, were able to function as coenzymes in the diol dehydrase reaction, coenzyme activity decreasing in that order. Like the native holoenzyme, complexes of the enzyme with these four analogs show a cob(II)alamin-like absorption peak or shoulder in the presence of 1,2-propanediol. Analogs containing hypoxanthine, cytosine, or benzimidazole do not function as coenzymes, but are weak competitive inhibitors in the presence of adenosylcobalamin. Analogs in which the D-ribosyl moiety is replaced by L-ribose or by an alkyl chain of 2 to 6 carbons are inactive as coenzymes, but act as competitive inhibitors with extremely high affinity for the apoenzyme. Complexes with the inactive analogs showed visible spectra similar to those of the corresponding free cobalamins. Upon anaerobic photolysis and subsequent aeration, complexes with the first group of inactive analogs produced unusually stabilized cob(II)alamin, while complexes with the second group of inactive analogs were readily photolyzed to a hydroxocobalamin-enzyme complex. Complexes with adeninylpentyl- and L-adenosylcobalamin were stable to light under the same conditions. These findings suggest that both the ribose and the adenine moiety of the nucleoside participate in enzyme-coenzyme interaction, involving not only the binding to the apoenzyme but also the activation of the carbon-cobalt bond.

Apoenzymes↗
PubMed1976

Lesions associated with familial polyposis coli: studies of lesions of lesions of the stomach, duodenum, bones, and teeth.

The entire gastrointestinal tract and bones were examined systematically in 24 patients (10 pedigrees) in whom familial polyposis coli was diagnosed. Polypoid lesions were observed in the stomach in as high as 68.2% of the cases, and in the duodenum in 90%. Abnormalities were noted in the skeleton in 50% and in the mandible in 81.3%. The authors emphasize the possibility that familial polyposis coli is substantially the same entity as Gardner's Syndrome.

Adolescent↗