Uptake and metabolism of the antidepressants sertraline, clomipramine, and trazodone in a garden cress (Lepidium sativum) model

Environmental contamination with pharmaceuticals has received growing attention in recent years. Several studies describe the presence of traces of drugs in water bodies and soils and their impacts on nontarget organisms including plants. Due to these facts investigations of the uptake and metabolism of pharmaceuticals in organisms is an emerging research area. The present study demonstrates the analysis of three selected antidepressants (sertraline, clomipramine, and trazodone) as well as metabolites and transformation products in a cress model (Lepidium sativum). Cress was treated with tap water containing 10 mg/L of the parent drugs. Employing an analytical approach based on high performance liquid chromatography coupled with quadrupole time of flight or Orbitrap mass spectrometry in MS and MS² modes, in total 14 substances were identified in the cress extracts. All three parent drugs were taken up by the cress and translocated from the roots to the leaves in specific patterns. In addition to this, eleven metabolite species were identified. They were generated by hydroxylation, demethylation, conjugation with amino acids, or combinations of these mechanisms. Finally, the inclusion of control cultures in the experimental setup allowed for a differentiation of "true" metabolites generated by the cress and transformation products generated by plant-independent mechanisms.

The influence of various storage conditions on cell viability in amniotic membrane

Up to now freeze-dried, gamma-sterilised or glycerol-preserved amniotic membranes (AMs) have widely been used in the field of ophthalmology and wound care (e.g. leg ulcers, burns). After some preservation processes in use, like freeze-drying or glycerol-preserving, the cells in the AM are no longer viable. Within this study we evaluated the influence of different short-term and long-term storage conditions on cell viability in AM. Therefore AMs from cesarean section placentae were washed and biopsied to evaluate the microbiological status and to determine the viability of the tissue. Additionally, viability under various storage conditions was examined by assessment of mitochondrial activity. Preservation included temperatures above and below 0 degrees C as well as various media compositions. As expected, cell viability in amnion decreases during storage, in fact the effect was more pronounced when stored frozen, but the higher viability of amnion obtained by storage above 0 degrees C with medium is associated with the limitation to a short period of storage of about 28 days. The evaluated preservation methods are the basis for future non-clinical in-vivo studies in which the possible benefit of amnion as a viable biomaterial in wound healing will be investigated.

Identification of benz(othi)azepine-binding regions within L-type calcium channel alpha1 subunits

To identify the binding domain for diltiazem-like Ca2+ antagonists on L-type Ca2+ channel alpha1 subunits we synthesized the benzazepine [3H]benziazem as a novel photoaffinity probe. [3H]Benziazem reversibly labeled the benzothiazepine (BTZ)-binding domain of partially purified skeletal muscle Ca2+ channels with high affinity (Kd = 12 nM) and photoincorporated into its binding domain with high yield (>66%). Antibody mapping of proteolytic labeled fragments revealed specific labeling of regions associated with transmembrane segments S6 in repeats III and IV. More than 50% of the labeling was found in the tryptic fragment alanine 1023-lysine 1077 containing IIIS6 together with extracellular and intracellular amino acid residues. The remaining labeling was identified in a second site comprising segment S6 in repeat IV and adjacent residues. Unlike for dihydropyridines, no labeling was observed in the connecting IIIS5-IIIS6 linker. The [3H]benziazem photolabeled regions must be in close contact to the drug molecule when bound to the channel. We propose that the determinants for high affinity BTZ binding are located within or in close proximity to segments IIIS6 and/or IVS6. Therefore the binding domain for BTZs, like for the other main classes of Ca2+ antagonists, must be located in close proximity to pore-forming regions of the channel.

An automated fast MR-imaging method for localized measurements of dose distributions using NMR-Fricke gel dosimetry. Evaluation of influences on the measurement accuracy

PURPOSE

The calculation of radiation absorbed dose using a chemical dosimeter and NMR-imaging techniques provides non-invasive 3D dosimetry. The main problems with this new method are measurement accuracy and diffusion effects. These involve influences on chemical preparations, correct data acquisition (evaluation of the T1 values) and a lack of methods for reducing diffusion effects. The aim of this study was to develop a computer assisted localized dosimetry method using fast and quantitative NMR-imaging techniques in order to reduce diffusion effects and to determine the accuracy of this new approach. We show successful localized dosimetry experiments and present a new method for the calculation of the diffusion coefficient.

MATERIAL AND METHODS

The dosimeter gel contained a modified Fricke solution and was stabilized with gelatin. Several compositions of dosimeter gels and different conditions were investigated in order to optimize the treatment. IR-Snapshot-Flash has been used to determine the T1-values. The diffusion coefficient of the bound ferric ions was estimated by taking advantage of the short acquisition times of this fast NMR-imaging technique.

RESULTS

Dependencies of the dosimeter system were investigated. The calculated error limits for evaluation of the measurement accuracy are in the range of 10 to 20%. The accurate localized determination of the T1-values and the diffusion has considerable influence on the measurement. Fast and quantitative NMR-imaging methods for accurate T1-calculations like IR-Snapshot-Flash reduce this effect.

CONCLUSION

Our results show the advantage of the use of fast MR-imaging techniques for NMR Fricke dosimetry. The diffusion effects are reduced effectively, so even details can be imaged. We also developed a new method for the calculation of the diffusion coefficient, which can be used for paramagnetic ions in any aqueous solution.