Biomedical subjects
Publications and source records attributed to G Wurm.
Thermal lumbar sympathectomy has been the method of choice since the 'eighties in the treatment of reflex dystrophy. We are using this method since January 1990. First results are presented and critically analysed. 15 patients who underwent thermal lumbar sympathectomy were examined and interviewed 1 year after treatment. 7 patients reported persisting pain relief, while the remaining 8 did not.
We studied the effects of 37 flavonoids on prostaglandin endoperoxide synthase (EC 1.14.99.1) purified from sheep vesicular glands. Nonplanar flavans were more potent inhibitors than planar flavones and flavonols (IC50 values were, e.g., 40 mumol/l for catechin and epicatechin, 110 mumol/l for galangin, 490 mumol/l for quercetin and 450 mumol/l for kaempherol). Different inhibition mechanisms were observed, i.e. uncompetitive inhibition for nonplanar flavonoids and competitive or noncompetitive inhibition for planar flavonoids. Potent inhibitors in the group of flavones were substances with an o-dihydroxy structure in the B ring and in the group of flavonol substances with two hydroxyl groups in position 5 and 7 of the A ring. None of the flavanones studied caused significant inhibition, except for the flavanone-3-ol, silibinin (silybin), which caused potent inhibition with an IC50 of 120 mumol/l. Several flavonoids, which were able to inhibit the prostaglandin endoperoxide synthase at higher concentrations, were also able to stimulate the enzyme at lower concentrations. These results indicate that the flavonoids should be divided into two groups according to their capacity to inhibit the prostaglandin endoperoxide synthase, represented by planar and nonplanar substances as in each group a close correlation between structure and inhibitory activity was observed.
We tested the ability of a wide variety of organic compounds, including benzene and phenol derivatives, aromatic amines, pyrazoline derivatives and other non-steroidal anti-inflammatory drugs, to act as cosubstrates during the horseradish peroxidase/hydrogen peroxide-mediated oxygenation of arachidonic acid. Structural requirements for drug activation in our system proved to be an aromatic system and ring substitution by an easily oxidizable group. Complementary substituents modified drug activation. Among the phenol derivatives and aromatic amines we found the meta-substituted compounds to be significantly more effective than their ortho- and para-substituted analogues, indicating the involvement of radical intermediates in this type of reaction. The radical from 1-phenyl 3-methyl 2-pyrazolone(5) was detected by electron paramagnetic resonance spectroscopy. Kinetic studies on this radical were in good accordance with time-dependent measurement of arachidonic acid oxygenation.
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Studies on the combined effects of a variety of lipoxygenase inhibitors and cyclo-oxygenase inhibitors revealed strong evidence for the existence of supplementary binding sites on lipoxygenases which modify the reactions of inhibitors with the catalytic site of the enzyme. Independent of their low or non-existent inhibitory reaction at the catalytic site, compounds which interact more effectively with this putative supplementary site are capable of blunting the inhibitory efficacy of potent lipoxygenase inhibitors. Although the degree of interaction with the catalytic site determines the potency of inhibitors, an additional reaction at the supplementary site is also obligatory for inhibitory efficacy. We found that potent lipoxygenase inhibitors possess high affinities for both sites, whereas weak inhibitors and suitable cyclo-oxygenase inhibitors interact predominantly with the supplementary site on the lipoxygenase and possess low or negligible affinities for its catalytic site.
The stimulating or inhibiting influences of 33 phenolic compounds on the prostaglandin synthetase of rat renal medulla were tested. Dihydroxyphenylcarbonic acids clearly proved to be activators of the prostaglandin synthetase. Dimethoxyphenylcarbonic acids were ineffective. Aminoethylphenols as well as p-substituted monohydroxybenzenes with a carbonic acid side chain were clear stimulators in contrast to their alkyl derivatives which are pronounced inhibitors. Among the tested bioflavonoids (+)-cyanidanol-3 and morin were inhibitors of the prostaglandin synthesis. Flavonoids with polar substitution in 3,5,7-position such as rutin on the other hand showed activating properties.
The passive cutaneous anaphylaxis (PCA) activities of a number of new A- and B-ring carboxyflavone and carboxyflavonol derivatives with planar and without planar orientation of the B-ring--synthesized in relation to baicalein and 2-carboxyxanthone derivatives as antianaphylactic prototypes--are recorded. From the investigated compounds A-ring carboxylic acids are more active than B-ring carboxy derivatives and flavonols are less active than flavones. Problems resulting from the correlation of the PCA activity of a number of chromone derivatives with the substitution of the 3-position are discussed.
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