Biomedical subjects
H Bohner
Publications and source records attributed to H Bohner.
Relative bioavailability of different butamirate citrate preparations after single dose oral administration to 18 healthy volunteers.
Eighteen volunteers have been treated with different oral formulations of butamirate citrate according to 2 randomized 2-way crossover designs. In the first study (study I) the test preparation was a syrup (Demotussol Hustensirup, Demopharm), and the reference preparation was a syrup already marketed (Sinecod Sirup, Zyma SA). A test preparation (Demotussol Tabletten) was compared to a solution (Demotussol Hustentropfen) in the second study (study II). Within the 2 study periods the volunteers received single 45 mg doses of the test and the reference formulation, respectively. Blood samples have been drawn immediately prior to each administration and at 17 sampling points within 96 h after dosing. A wash-out period of 1 week was maintained between successive drug doses. The plasma concentration of one of the main metabolites, 2-phenylbutyric acid, was determined by a validated reversed-phase HPLC method with UV detection, with a lower limit of quantification of 50 ng/ml. The following mean values have been obtained in study I (syrup preparations) for the test: AUC0-infinity 46.9 micrograms x h/ml, Cmax of 1.77 micrograms/ml at 1.1 h, t1/2 28 h and after administration of the reference: AUC0-infinity 50.4 micrograms x h/ml, Cmax 1.86 micrograms/ml, tmax 1.5 h, t1/2 26 h. In study II the following mean values have been obtained for the test preparation (tablet): AUC0-infinity 54.7 micrograms x h/ml, Cmax of 1.88 micrograms/ml at 1.1 h, t1/2 27 h and for the reference (solution): AUC0-infinity 54.5 micrograms x h/ml, Cmax 1.94 micrograms/ml, tmax 1.1 h, t1/2 26 h. Both preparations have been proven to be bioequivalent to their corresponding references regarding extent and rate of absorption.
[Exercise performance after long-term administration of enalapril or metoprolol. A randomized double-blind study of hypertensive leisure-time sportsmen].
A randomized double-blind trial was conducted in 36 leisure-time sportsmen (mean age 40.1 +/- 5.4 years) with mild or moderate essential hypertension (WHO groups I or II) to find out whether an 8-week antihypertensive treatment with daily 10-20 mg enalapril or 100-200 mg metoprolol changed their exercise performance. This was measured by bicycle spiroergometry together with determination of lactate levels, before and at the end of the treatment period. Maximal oxygen uptake rose by 1.86 ml/kg.min during enalapril administration and by 1.06 ml/kg.min at the individual anaerobic threshold. But under metoprolol these parameters fell by 6.57 ml/kg.min and 4.61 ml/kg.min, respectively. After treatment with these two drugs 3 and 15 patients, respectively, had the sensation of greater exercise performance at identical exercise levels. The differences in exercise between the two drugs using the stated three primary criteria were statistically significant. The Watt-time product decreased in only one of the patients of the enalapril group, but in 17 of the metoprolol group. Only metoprolol significantly reduced exercise heart rate. Both drugs caused a similar fall in systolic blood pressure during exercise.
Formation of silver plastocyanin in Scenedesmus.
Silver ions up to 5 microM do not affect growth of the green microalga Scenedesmus acutus. They induce formation of protein species precipitable by an antibody specific against plastocyanin. The metal is incorporated into a part of the induced protein in competition with copper. Bismuth, lead and molybdenum had no effect. The amount of both silver- and copper-containing plastocyanins so formed apparently regulates concurrently inhibition of soluble plastidic cytochrome c-553. The silver-copper competition for the build-up of blue plastocyanin can be shown with intact cells, not with isolated algal plastocyanin.
Reciprocal formation of plastocyanin and cytochrome c-553 and the influence of cupric ions on photosynthetic electron transport.
The green alga Scenedesmus acutus is able to synthesize plastocyanin and cytochrome c-553. The concentrations of plastocyanin and cytochrome c-553 vary inversely in response to the cupric-ion concentrations of the growth medium (Bohner, H. and Böger, P. (1978) FEBS Lett. 85, 337-339). Both proteins form a homogeneous donor pool to the reaction center of Photosystem I. This donor pool can be varied quantitatively and qualitatively by different growth conditions. These variations have no influence on algal growth or photosynthetic electron transport as measured in vivo by oxygen evolution, fluorescence induction and cytochrome f-553 and c-553 redox reactions using Cu2+ concentrations of less than 10 microM in the culture medium. At higher cupric-ion concentrations, which already retard algal growth, specific sites of the photosynthetic electron-transport chain are affected: the oxidizing side of Photosystem II and the reducing side of Photosystem I.
High variability of the electron carrier plastocyanin in microalgae.
1. The plastocyanin content of Scenedesmus can be dramatically varied with the copper content of the culture medium. Figures as high as 7 mmol plastocyanin/mol chlorophyll are possible. Electron paramagnetic resonance (EPR) spectroscopy has been used to determine this physiological response quantitatively in intact cells having different amounts of plastocyanin. The results obtained by the EPR technique were compared with data on isolated plastocyanin determined either by spectrophotometry or immunoelectrophoresis. Agreement was found for the amount of plastocyanin detected by the first two methods, whereas the last assay yielded data at least 25% higher on the average. Under all culture conditions a copper-free plastocyanin precursor is present. 2. The EPR properties of purified plastocyanin and those of cellular plastocyanin located within the thylakoids are practically identical in terms of g-values, hyperfine splittings, signal linewidths and saturation behavior at temperatures of 12--15 K. Our data indicate that plastocyanin is not present in a membrane-bound form but exists as a single soluble pool. 3. The studies have been extended to the algae Dunaliella parva and Bumilleriopsis filiformis. The first species exhibits a limited variation of plastocyanin with the copper content of the medium. Furthermore, no cytochrome c-553 could be detected in Dunaliella even under conditions of copper deficiency. In contrast, Bumilleriopsis does not contain plastocyanin regardless of the amount of copper offered.
Reciprocal formation of cytochrome c-553 and plastocyanin in Scenedesmus.
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Reactivity of germ-free and conventional mice to pertussis vaccine.
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