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Biomedical subjects

J Ziegler

Publications and source records attributed to J Ziegler.

At least 37 records · Page 2Linked to original sources
PubMed1999

On the specificity of allene oxide cyclase.

Jasmonic acid is a carbocyclic fatty acid that is biosynthesized from alpha-linolenic acid in several steps. The formation of the ring structure of jasmonic acid is catalyzed by the enzyme allene oxide cyclase (EC 5.3.99.6) and involves the cyclization of an unstable allene oxide into the cyclopentenone 12-oxo-10,15(Z)-phytodienoic acid. In this study, a number of allene oxides were generated, and their enzymatic and nonenzymatic cyclization into cyclopentenones was investigated. Nonenzymatic cyclization was observed with allene oxides having one pair of conjugated double bonds and an additional isolated double bond in the beta,gamma position relative to the epoxide group, i.e., the partial structure 4,5-epoxy-1,3,7-octatriene. Enzymatic cyclization took place provided that this structural element was inserted in the fatty acid chain with its epoxide group in the n-6,7 position and the isolated double bond in the n-3 position. A number of oxygenated fatty acids having structural features in common with the natural allene oxides were tested as inhibitors of allene oxide cyclase. Fatty acids having an allene oxide structure in the n-6,7 position but lacking the double bond in the n-3 position, as well as fatty acids having a saturated epoxide group in the n-6,7 position, served as competitive inhibitors of the enzyme. Data on the substrate specificity of allene oxide synthase (EC 4.2.1.92) from corn seeds indicated that fatty acid hydroperoxides with a double bond at n-3 and with the hydroperoxide function at n-6 exhibit the highest affinity but the slowest reaction velocity.

Animals↗
PubMed1999

Practitioners and saints: medical men in canonization processes in the thirteenth to fifteenth centuries.

This article shows that recourse to expert medical judgement for authenticating miracles has medieval roots which lead to the thirteenth century. It provides a survey of those cases in the printed versions of canonization processes from c. 1200 to c. 1500 where medical men actively appeared as witnesses. It shows how, from the second half of the thirteenth century, many canonization processes (overwhelmingly in southern Europe) included at least one medical man who witnessed or gave expert testimony as a supplier of medicine. The physicians who appeared as expert witnesses were expected to rule out the possibility that there was a natural explanation for the wonderous cure. To acquire medical confirmation that a certain cure was miraculous seemed highly desirable to those wishing to substantiate claims of sanctity. Physician witnesses were often called upon to evaluate cases of which they had personal knowledge because of the medical know-how they possessed: however, medical science was not considered so universal that any physician could review the case (as is theoretically the case today in the medical council at the Vatican). Thus, to the therapeutic function of physicians and surgeons in southern Europe from the second half of the thirteenth century, a hitherto neglected duty should be added: whenever necessary, the community as well as the local ecclesiastical authorities expected the suppliers of medical services to contribute to the formal recognition of an apparent saint.

Catholicism↗
PubMed1998

Mosaicism in X-linked severe combined immunodeficiency.

We performed gamma c gene analysis of a boy with severe combined immunodeficiency whose brother died of the same condition. A base pair deletion in exon 6 was found, which was absent in his mother, indicating maternal mosaicism with important implications for genetic counseling and demonstrating the importance of mutation analysis in boys with severe combined immunodeficiency.

Biomarkers↗