[Extracorporeal Membrane Oxygenation in the Therapy of Cardiogenic Shock Due to Fulminant Myocarditis].

This article presents a clinical case of a 40-year-old woman with fulminant myocarditis which progressed rapidly to the development of cardiogenic shock resistant to standard intensive care, but with a positive response to extracorporeal membrane oxygenation.

Free radical lipid peroxidation inhibits enzymatic conversion of beta-carotene into vitamin A.

Free radical oxidation of arachidonic acid with soybean lipoxygenase was accompanied by inhibition of retinal synthesis from beta-carotene catalyzed by enzyme preparation from rabbit intestinal mucosa. Lipoxygenase inhibitor salicylhydroxamic acid and antioxidants suppressing free radical reactions (ethyl gallate, alpha-tocopherol, astaxanthine, and quercetin) promoted conversion of beta-carotene into retinal catalyzed by beta-carotene-15,15'-dioxygenase. These results indicate that lipoperoxides and/or products of their homolysis attenuate enzymatic conversion of beta-carotene and confirm the important role of natural antioxidants in the maintenance of stable vitamin A content in mammals.

Some natural and synthetic antioxidants as stabilizers of beta-carotene conversion into vitamin A.

The effect of antioxidants (vitamins C and E, quercetin, probucol, butylated hydroxytoluene) on the oxidation of beta-carotene and its conversion into retinal under the influence of beta-carotene 15,15'- dioxygenase (CDO) from rat intestinal mucosa was studied. The activity of CDO decreased in the presence of oxidants. Antioxidants protected both the substrate and the enzyme. The extent of the protection depended on the antioxidant type. The combined injection of antioxidants and beta-carotene to animals completely or partially prevented the inhibition of the intestinal CDO which was caused by products of non-enzymatic oxidation of beta-carotene. Vitamins C and E, which protected the enzyme--substrate complex in vivo and in vitro, were found to be the most efficient protectors of beta-carotene conversion into retinal.

[Conversion of beta-carotene and some beta-apocarotinoids under the effect of substances from the intestinal mucosa]. / Issledovanie prevrashcheniia beta-karotina i nekotorykh beta-apokarotinolov pod deistviem preparatov mukoidal'nogo sloia kishechnika.

Products of cleavage of beta-carotene and certain apocarotenoids (beta-apo-4', 8', 10', and 12'-carotenols and citranaxanthol) were studied, and the dynamics of their generation in the presence of an enzyme preparation isolated from rabbit intestinal mucosa was determined. The data suggest that metabolism of beta-apocarotenols involves the production of retinal and beta-apo-14'-carotenal mediated by enzymes different from beta-carotene-15,15'-dioxygenase, which converts beta-carotene to retinal. A scheme of metabolic conversion of beta-carotene is discussed.

Enzymatic oxidation of beta-apo-8'-carotenol to beta-apo-14'-carotenal by an enzyme different from beta-carotene-15,15'-dioxygenase.

Extracts of rat and rabbit intestinal mucosa were fractionated with ammonium sulfate. The precipitate contained beta-apocarotenoid-14',13'-dioxygenase (ADO) activity. beta-Apo-14'-carotenal was found to be the product of enzymatic cleavage of beta-apo-8'-carotenol. Activities of ADO and beta-carotene-15,15'-dioxygenase (CDO) were detected in the presence of thiols and were inactivated by 1,10-phenanthroline. Optimal pH values were 7.0 for ADO and 8.0 for CDO. Heating at 52 degrees C inhibited ADO by 70% and produced no effect on CDO. ADO activity was maximal in the presence of sodium cholate or 3-[(3-cholamidopropyl)-dimethyl-ammonio]-1-propanesulfonate (CHAPS). Sodium dodecylsulfate was required for maximal CDO activity. Proteins with ADO activity were not retained by phenyl-Sepharose CL-4B. CDO activity was eluted from columns only in the presence of detergents. The data suggest that the enzymes that catalyze the oxidative cleavage of beta-carotene to yield retinal are different from those that cleave beta-apo-8'-carotenol to yield beta-apo-14'-carotenal.