PubMed Health⌕ Search

Biomedical subjects

B Wiesen

Publications and source records attributed to B Wiesen.

9 recordsLinked to original sources
PubMed1998

Characterization of enzymes from Ancistrocladus (Ancistrocladaceae) and Triphyophyllum (Dioncophyllaceae) catalyzing oxidative coupling of naphthylisoquinoline alkaloids to michellamines.

Peroxidase active preparations from three Ancistrocladus species and from Triphyophyllum peltatum have been partially purified. They catalyze the oxidative dimerization of korupensamines A and B to michellamines A and C, respectively, as well as the mixed coupling to michellamines A, B, and C. All of these enzymes consist of single polypeptides of approximately 65 kDa with peroxidase activity as monomers. They were characterized as soluble proteins predominantly localized in the leaf phloem of all species examined. Comparative studies with various naphthol precursors revealed an unexpected substrate specificity. Only korupensamines were dimerized by the enzymes, while other monomers, even if closely related, were not accepted as substrates. The coupling reactions described here represent the first direct synthesis of michellamines from korupensamines without previous protection of these precursors.

Alkaloids↗
PubMed1997

Dioncophylline A as a growth-retarding agent against the herbivorous insect Spodoptera littoralis: structure-activity relationships.

Dioncophylline A (1) represents a novel insecticidal agent, as documented by its enhanced growth-retarding effect on larvae of the polyphagous pest insect Spodoptera littoralis. Within the scope of the work described here, the potential of this as yet most active naphthylisoquinoline alkaloid was further elucidated by the preparation and testing of selected analogues. Investigation of a broad series of structurally modified dioncophylline A analogues (2-20) revealed the free amine function to be essential for the growth inhibitory effect, whereas a modification of the OH function partially led to a distinct increase of activity. In particular, the 8-O-alkyl (especially 8-O-benzylated) derivatives (14 and 15 as well as 16-19) displayed pronounced effects. In the case of 8-O-(p-bromobenzyl)dioncophylline A (16), the activity of the natural parent compound dioncophylline A (1) (EC50 = 277 micrograms/g fresh wt of diet; concentration that inhibits larval growth by 50%) was even improved by a factor of > 15 (EC50 = 15.6 micrograms/g fresh wt).

Animals↗
PubMed1990

The use of rapeseed screenings in diets for lactating cows and subsequent effects on milk yield and composition.

This trial was to determine the effect of dietary rapeseed screenings on milk production, milk composition, and feed intake of lactating dairy cows. Pelleted rapeseed screenings were fed at 0, 7, and 14% of diet DM. Assignment of 36 multiparous Holstein cows was based upon parity and previous lactation performance. The experimental period was from parturition through wk 16 of lactation. The control ration had 3.1% ether extract, whereas the ration with 14% rapeseed screenings had 5.4% ether extract. The rapeseed screenings contained 52.2% of C18:1 and 24.2% of C18:2 as percentage of total fatty acids. There were no significant effects of dietary treatment on milk yield or feed intake. There were significant increases in milk fatty acids C18:1 and C18:2 for cows consuming the diets with rapeseed screenings. Treatment did not significantly affect milk protein percentage as measured by Kjeldahl N or by the infrared method. Increased unsaturated fatty acids in the milk of cows fed rapeseed screenings had no apparent effect on infrared fat analysis. There was no interaction of treatment and milk fat analysis method (infrared versus Babcock). Dietary treatment did not affect blood serum nonesterified fatty acid concentrations over the 16-wk period. In conclusion, rapeseed screenings, fed at levels up to 14% of the diet, did not affect milk yield, milk protein, or milk fat percentage but did change milk fatty acid composition.

Amino Acids↗
PubMed1988

[The cast walking shoe combined with modern synthetic support bandages].

Rehabilitation with regard to mobility and function of immobilized lower extremities can be speeded up if the patient can move more frequently and freely with a loadbearing cast. This paper reports on the use of a new external cast system together with a cast shoe. Based on documented cases of empirical experience it is demonstrated that in many cases patients can return to work despite having to wear a cast.

Adult↗