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Biomedical subjects

S Aoyagi

Publications and source records attributed to S Aoyagi.

At least 289 records · Page 16Linked to original sources
PubMed1980

The characteristics of anticoagulation by covalently immobilized heparin.

The reactions of covalently immobilized heparin, abbreviated as I-Hep, with thrombin or Factor Xa were investigated both in the presence and absence of antithrombin III, AT III. Although I-Hep was able to bind to thrombin, the complex formation of thrombin and I-Hep did not affect the thrombin activity when measured by using a small artificial substrate, a peptide-MCA. Similarly, Factor Xa bound to I-Hep, but the activity of Factor Xa was not decreased in the absence of AT III, when a peptide-MCA was used for Factor Xa assay. Thrombin bound to I-Hep in much larger amounts than Factor Xa. Thrombin and Factor Xa were instantaneously inhibited by AT III in the presence of soluble heparin. However, when I-Hep was used instead of soluble heparin, instantaneous inhibition was not observed. When a natural, high-molecular-weight substrate was used for assay, the results were dependent on the structure of the immobilization carrier. Heparin immobilized on Sepharose 4B or Poly HEMA showed considerable prolongation of plasma recalcification time. However, heparin immobilized on the surface of PVA fiber did not prolong plasma recalcification time.

Antithrombin III↗
PubMed1980

Anticoagulant activity of artificial biomedical materials with co-immobilized antithrombin III and heparin.

An approach to providing anticoagulant activity to biomedical materials was presented, applying an immobilization technique. Antithrombin III (AT III) inactivates the activated coagulation factors including Factor Xa and thrombin. Heparin stimulates the inactivation of Factor Xa and thrombin by AT III. Thus AT III and heparin were co-immobilized on Sepharose 4B, polyvinyl alcohol, polyhydroxy-ethyl methacrylate and silicone-coated nylon by the cyanogen bromide procedure. Those co-immobilized preparations, abbreviated as I-AT III . Hep, actively neutralized both Factor Xa and thrombin. The activity of I-AT III . Hep was much higher than immobilized heparin and/or immobilized AT III. I-AT III . Hep, like soluble AT III and heparin, instantaneously neutralized both thrombin and Factor Xa. When two enzymes, thrombin and Factor Xa, were present, I-AT III . Hep neutralized Factor Xa in preference to thrombin : The neutralization of thrombin was inhibited by the presence of Factor Xa, but neutralization of Factor Xa was independent of the presence of thrombin. The amount of Factor Xa neutralized was higher than that of thrombin.

Animals↗
PubMed1979

Strain differences in rat liver (UDP-glucuronyltransferase activity towards androsterone.

Male Donryu, Wistar King rats showed discontinuous variations in hepatic microsomal UDP-glucuronyltransferase activities towards androsterone, but not towards testosterone, bilirubin, phenolphthalein and 4-nitrophenol. Fresh microsomal fraction with a low transferase activity towards androsterone formed 0.049--0.080 nmole of glucuronide/min per mg of protein, whereas fresh microsomal fraction with a high transferase activity towards androsterone formed 0.335--0.557 nmol of glucuronide/min per mg of protein. The microsomal fraction with low enzyme activity towards androsterone was not stimulated by treatment with Triton X-100 or freezing and thawing. In contrast, male Long Evans and Sprague-Dawley rats did not exhibit such diversity.

Androsterone↗
PubMed1979

Biological studies on the degradation products of 3-[(S)-1'-phenylethylamino]propylaminobleomycin: a novel analog (pepleomycin).

Pepleomycin (PEP), 3-[(S)-1'-phenylethylamino]propylaminobleomycin has potent activity and is less pulmonary toxic than bleomycin (BLM). Biological activity and toxicity of the following degradation products of PEP have been studied in detail: the product of carbamoyl migration (ISO), the product of decarbamylation (DC), the product of ring closure of the side chain on the pyrimidine moiety (RC), the depyruvamide product (DP) and the product of an enzymatic inactivation (DA). These degradation products showed much lower activity than PEP in vitro: antimicrobial and anti-HeLa activities, inhibition of DNA synthesis in AH66 cells and the DNA strand cleavage. Acute toxicity and pulmonary toxicity were tested in mice. Results indicated much lower acute toxicity corresponding to the decreased in vitro activity when compared to PEP. DP and RC did not cause lung fibrosis in mice, while ISO and DC showed 1/2.6 and 1/5.7 degree of pulmonary toxicity, respectively, in comparison with PEP.

Animals↗