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Biomedical subjects

U Sankawa

Publications and source records attributed to U Sankawa.

At least 91 records · Page 5Linked to original sources
PubMed1983

A cleavage product of mouse C3 adsorbable to (1----3)-beta-D-glucan from Alcaligenes faecalis var. myxogenes IFO 13140.

By using affinity chromatography of TAK, a gel-forming antitumor (1----3)-beta-D-glucan produced by Alcaligenes faecalis var. myxogenes IFO 13140 also known as an activator of the alternative complement pathway (ACP), we obtained from mouse serum a cleavage product of C3 (tentatively designated as C3X). Binding between C3X and TAK seemed to be noncovalent. In contrast to C3, C3X had an intact beta chain (70,000 daltons) and instead of an alpha chain, two peptide chains (40,000 and 30,000 daltons) linked by disulfide bonds. C3X retained a portion of C3 antigenicity. By trypsinolysis C3 yielded a fragment similar to C3X on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These results suggest that C3X is C3c. Since C3X was obtained by elution with a high salt solution from TAK incubated with ethylenediaminetetraacetate (EDTA)-serum (serum containing EDTA) but not from TAK incubated with EDTA-plasma, C3X could already be present in the serum before the activation of ACP by TAK.

Adsorption↗
PubMed1982

Depside as potent inhibitor of prostaglandin biosynthesis: a new active site model for fatty acid cyclooxygenase.

Forty depsides and depsidones, the esters of phenolcarboxylic acids, were examined for their inhibitory effect against prostaglandin biosynthesis with rabbit renal microsomes. 4-0-Methylcryptochlorophaeic acid was the most active inhibitor so far tested and its IC50 value was 0.34 muM. Kinetic investigation has shown that this depside acts competitively with respect to arachidonic acid as most of the non - steroidal antiinflammatory drugs. X-Ray analysis has revealed that 4-0-methylcryptochlorophaeic acid maintains its rigid conformation by forming a strong hydrogen bond between the hydroxyl and methoxyl groups. Comparison of CPK models between 4-0-methylcryptochlorophaeic acid and non-steroidal antiinflammatory drugs revealed that the carboxyl group and the two rings of these drugs are almost superimposable to those of the depside. This finding led us to propose a new active site model based on the three dimentional structure of the depside.

Animals↗
PubMed1980

Phosphatidylcholine liposomes containing cholesterol analogues with side chains of various lengths.

The effect of the length of the side chain of sterols on their interaction with phosphatidylcholine was studied by measuring the permeability properties of liposomes constituted with sterol analogues with side chains of various lengths. The sensitivities of liposomes constituted with these sterol analogues toward digitonin and polyene antibiotics were also examined. The effects of sterols on phase transition of phosphatidylcholine were examined by measuring their effects on permeability increase due to perturbation of phase equilibrium and by differential scanning calorimetry. An analogue with a short side chain, isopropyl (C-22), had a very similar effect to cholesterol in suppressing the permeability increase, suggesting that the full length of the side chain is not necessary for this effect. The permeability of egg yolk phosphatidylcholine at 42 degrees C was suppressed as much by the analogue C-22 as by cholesterol. Androstene-3-beta-ol, an analogue without a side chain, however, had little suppressive effect. Thus it is concluded that the condensing effect of sterol requires a side chain, but not the full length of side chain. Liposomes constituted with analogues having a side chain with more than 5 carbon atoms showed maximum reactivity with a polyene antibiotic, amphotericin B, whereas those constituted with analogues having a side chain with less than 4 carbon atoms showed weaker reactivity. These findings indicate that a side chain with more than 5 carbon atoms is essential for the maximum interaction of liposomes with amphotericin B. Unlike amphotericin B, filipin reacted almost equally well with liposomes containing C-22 and with those containing cholesterol. Thus the chain length of the side chain of sterol is less important for interaction of liposomes with filipin than for their interaction with amphotericin B. Liposomes containing analogues having a side chain with more than 6 carbon atoms showed maximum reactivity with digitonin. Thus for the maximum interaction of liposomes with digitonin, the side chain of sterol should be longer than 6 carbon atoms.

Anti-Bacterial Agents↗