Teleradiology requirements and aims in Germany and Europe: status at the beginning of 2000.

Specific radiological requirements have to be considered for realization of telemedicine. In this article the goals and requirements for an extensive implementation of teleradiology are defined from the radiological user's point of view. Necessary medical, legal and professional prerequisites for teleradiology are presented. Superior requirements, such as data security and privacy or standardization of communication, must be realized. Application specific requirements, e. g. quality and extent of teleradiological functions as well as technological alternatives, are discussed. Each project must be carefully planned in relation to one's own needs, extent of functions and system selection. Topics like legal acceptance of electronic documentation, reimbursement of teleradiology and liability must be clarified in the future.

Collagen gel immobilisation provides a suitable cell matrix for long term human hepatocyte cultures in hybrid reactors.

An easy to apply culture technique is presented that protects a monolayer configuration of liver cells within an extracellular matrix. The Immobilising Gel (IG)-Technique not only preserves hepatocyte morphology and supports a variety of differentiated cell functions over long term periods, but also offers higher resistance of IG-culture systems against shear forces of fluids in a hybrid reactor device, as compared to other culture techniques. Human hepatocyte cultures in IG-Technique: DNA-normalised levels for the total production of cholinesterase, albumin, urea and lactate remained high throughout the investigational period (50 days). Glutamic-Pyruvic-Transaminase (GPT) release decreased after peak values during early culture adaptation. Electron Microscopic (EM) findings after the shear forces experiment revealed undisturbed subcellular structures and a preserved intercellular morphology, including bile canaliculi and desmosomes. We conclude that the IG-technique is of considerable advantage as compared to other culture systems, especially in the field of dynamic applications, e.g. hybrid reactors for artificial organ development.

Biosynthesis of cyclopentenyl fatty acids. Cyclopentenylglycine, a non-proteinogenic amino acid as precursor of cyclic fatty acids in Flacourtiaceae.

In seeds of Hydnocarpus anthelminthica of Flacourtiaceae, cyclopentenylglycine and cyclopentenyl fatty acids are found naturally. The non-proteinogenic amino acid may serve as precursor of cyclopentenyl fatty acids via aleprolic acid, the starter molecule for these long-chain compounds. After administration of cyclopentenyl[2-14C]glycine to maturing seeds of H. anthelminthica, labelled cyclopentenyl fatty acids were synthesized. Comparative activities were observed, when [1-14C]aleprolic acid was supplied to the seeds. Incorporation studies with [1-14C]acetate revealed that the chain-lengthening systems for straight-chain and cyclic fatty acids were still functioning in mature seeds. Endosperm and embryo of H. Anthelminthica seeds synthesized cyclopentenyl fatty acids from cyclopentenyl[2-14C]glycine, [1-14C]aleprolic acid and [1-14C]acetate. In embryonic tissue, a dilution experiment proved the following path for cyclopentenyl fatty acid biosynthesis: cyclopentenylglycine leads to aleprolic acid leads to cyclopentenyl fatty acids. The conversion of cyclopentenylglycine to aleprolic acid may occur via transamination and oxidative decarboxylation; activated aleprolic acid is then lengthened by C2-units to cyclopentenyl fatty acids.

Biosynthesis of cyclopentenyl fatty acids. (2-Cyclopentenyl)carboxylic acid (aleprolic acid) as a special primer for fatty acid biosynthesis in Flacourtiaceae.

The biosynthesis of cyclopentenyl fatty acids from (2-cyclopentenyl)carboxylic acid (aleprolic acid) via chain-lengthening by C2-units was tested in seeds and leaves of Caloncoba echinata and Hydnocarpus anthelminthica of Flacourtiaceae and in various prepatations of higher plants other than Fla courtiaceae. Only tissues of Flacourtiaceae, where cyclopentenyl fatty acids are found naturally, were able to accept aleprolic acid as a starter molecule for the synthesis of cyclic fatty acids. Labelling patterns of straight chain and cyclic fatty acids, synthesized after incubation of Flacourtiaceae seeds with [1-(14)C[-acetate, indicated de novo synthesis of C16 fatty acids in either case, followed by elongation to higher homologs.

Homologous synthesis: a method for the preparation of mixed substrates and individual compounds.

Equimolar mixtures of several homologous or vinylogous alkyl methanesulfonates (mesylates) are converted, by a series of reactions, into equimolar mixtures of compounds having one methylene group more, per molecule, than the starting material. Such mixtures can be used for studying the specificity of an enzymatic reaction in a single experiment in vivo or in vitro. The simultaneous synthesis of a mixture of compounds is also of great advantage in the preparation of a series of radioactively labelled substances. It is more convenient and much more efficient to prepare several labelled compounds of a homologous or vinylogous series in a single reaction, and to isolate each of them by chromatographic methods, than to synthesize the individual substances separately.