Rational design of highly stabilized and selective adrenomedullin analogs.

The peptide hormone adrenomedullin (ADM) consists of 52 amino acids with a disulfide bond and an amidated C-terminus. Due to the vasodilatory and cardioprotective effects, the agonistic activity of the peptide on the adrenomedullin 1 receptor (AM1 R) is of high pharmacological interest. However, the wild-type peptide shows low metabolic stability leading to rapid degradation in the cardiovascular system. Previous work by our group has identified proteolytic cleavage sites and demonstrated stabilization of ADM by lipidation, cyclization, and N-methylation. Nevertheless, these ADM analogs showed reduced activity and subtype selectivity toward the closely related calcitonin gene-related peptide receptor (CGRPR). Here, we report on the rational development of ADM derivatives with increased proteolytic stability and high receptor selectivity. Stabilizing motifs, including lactamization and lipidation, were evaluated regarding AM1 R and CGRPR activation. Furthermore, the central DKDK motif of the peptide was replaced by oligoethylene glycol linkers. The modified peptides were synthesized by Fmoc/t-Bu solid-phase peptide synthesis and receptor activation of AM1 R and CGRPR was measured by cAMP reporter gene assay. Peptide stability was tested in human blood plasma and porcine liver homogenate and analyzed by RP-HPLC and MALDI-ToF mass spectrometry. Combination of the favorable lactam, lipidation, ethylene glycol linker, and previously described disulfide mimetic resulted in highly stabilized analogs with a plasma half-life of more than 144 h. The compounds display excellent AM1 R activity and wild-type-like selectivity toward CGRPR. Additionally, dose-dependent vasodilatory effects of the ADM derivatives lasted for several hours in rodents. Thus, we successfully developed an ADM analog with long-term in vivo activity.

A Selective Carborane-Functionalized Gastrin-Releasing Peptide Receptor Agonist as Boron Delivery Agent for Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) allows the selective elimination of malignant tumor cells without affecting healthy tissue. Although this binary radiotherapy approach has been known for decades, BNCT failed to reach the daily clinics to date. One of the reasons is the lack of selective boron delivery agents. Using boron loaded peptide conjugates, which address G protein-coupled receptors overexpressed on tumor cells allow the intracellular accumulation of boron. The gastrin-releasing peptide receptor (GRPR) is a well-known target in cancer diagnosis and can potentially be used for BNCT. Here, we present the successful introduction of multiple bis-deoxygalactosyl-carborane building blocks to the GRPR-selective ligand [d-Phe6, ß-Ala11, Ala13, Nle14]Bn(6-14) (sBB2L) generating peptide conjugates with up to 80 boron atoms per molecule. Receptor activation was retained, metabolic stability was increased, and uptake into PC3 cells was proven without showing any intrinsic cytotoxicity. Furthermore, undesired uptake into liver cells was suppressed by using l-deoxygalactosyl modified carborane building blocks. Due to its high boron loading and excellent GRPR selectivity, this conjugate can be considered as a promising boron delivery agent for BNCT.

Fluorescently labeled adrenomedullin allows real-time monitoring of adrenomedullin receptor trafficking in living cells.

The human adrenomedullin (ADM) is a 52 amino acid peptide hormone belonging to the calcitonin family of peptides, which plays a major role in the development and regulation of cardiovascular and lymphatic systems. For potential use in clinical applications, we aimed to investigate the fate of the peptide ligand after binding and activation of the adrenomedullin receptor (AM1), a heterodimer consisting of the calcitonin receptor-like receptor (CLR), a G protein-coupled receptor, associated with the receptor activity-modifying protein 2 (RAMP2). Full length and N-terminally shortened ADM peptides were synthesized using Fmoc/tBu solid phase peptide synthesis and site-specifically labeled with the fluorophore carboxytetramethylrhodamine (Tam) either by amide bond formation or copper(I)-catalyzed azide alkyne cycloaddition. For the first time, Tam-labeled ligands allowed the observation of co-internalization of the whole ligand-receptor complex in living cells co-transfected with fluorescent fusion proteins of CLR and RAMP2. Application of a fluorescent probe to track lysosomal compartments revealed that ADM together with the CLR/RAMP2-complex is routed to the degradative pathway. Moreover, we found that the N-terminus of ADM is not a crucial component of the peptide sequence in terms of AM1 internalization behavior.

Selective Neuropeptide Y Conjugates with Maximized Carborane Loading as Promising Boron Delivery Agents for Boron Neutron Capture Therapy.

G-protein-coupled receptors like the human Y1 receptor (hY1R) are promising targets in cancer therapy due to their high overexpression on cancer cells and their ability to internalize together with the bound ligand. This mechanism was exploited to shuttle boron atoms into cancer cells for the application of boron neutron capture therapy (BNCT), a noninvasive approach to eliminate cancer cells. A maximized number of carboranes was introduced to the hY1R-preferring ligand [F7,P34]-NPY by solid phase peptide synthesis. Branched conjugates loaded with up to 80 boron atoms per peptide molecule exhibited a maintained receptor activation profile, and the selective uptake into hY1R-expressing cells was demonstrated by internalization studies. In order to ensure appropriate solubility in aqueous solution, we proved the need for eight hydroxyl groups per carborane. Thus, we suggest the utilization of bis-deoxygalactosyl-carborane building blocks in solid phase peptide synthesis to produce selective boron delivery agents for BNCT.

The Impact of Adrenomedullin Thr22 on Selectivity within the Calcitonin Receptor-like Receptor/Receptor Activity-Modifying Protein System.

Adrenomedullin (ADM) is a peptide hormone of the calcitonin gene-related peptide (CGRP) family. It is involved in the regulation of cardiovascular processes such as angiogenesis, vasodilation, and the reduction of oxidative stress. ADM mediates its effects by activation of the ADM-1 and -2 receptors (AM1 R/AM2 R), but also activates the CGRP receptor (CGRPR) with reduced potency. It binds to the extracellular domains of the receptors with its C-terminal binding motif (residues 41-52). The activation motif, consisting of a disulfide-bonded ring structure (residues 16-21) and an adjacent helix (residues 22-30), binds to the transmembrane region and stabilizes the receptor conformation in the active state. While it was shown that the binding motif of ADM guides AM1 R selectivity, there is little information on the activation motif itself. Here, we demonstrate that Thr22 of ADM contributes to the selectivity. By using solid-phase peptide synthesis and cAMP-based signal transduction, we studied the effects of analogues in the activation motif of ADM on AM1 R and CGRPR activity. Our results indicate that Thr22 terminates the α-helix and orients the ring segment by hydrogen bonding. Using olefin stapling, we showed that the α-helical arrangement of the ring segment leads to decreased AM1 R activity, but does not affect CGRPR activation. These results demonstrate that the conformation of the ring segment of ADM has a strong impact on the selectivity within the receptor system.

[The meaning of 'consensus' in the context of guidelines--an introduction into the problem]. / Die Rolle der Konsensbildung in Leitlinien Eine Einführung in die Problematik.

From the point of view of sociology a consensus may be incompatible with science. This also applies to consensus statements developed by a scientific medical society, since a lack of facts might have been replaced by a majority decision. This is in contrast to the idea of evidence-based medicine (EbM). Personal beliefs do not gain more plausibility (a higher level of evidence) by the mere fact that they are supported by a majority. Thus it is not helpful to demand that EbM-oriented guidelines also be consensus-based.

Adrenomedullin 2.0: Adjusting Key Levers for Metabolic Stability.

The 52 amino acid peptide hormone adrenomedullin (ADM) plays a major role in the development and regulation of the cardiovascular and lymphatic system and has therefore gained significant interest for clinical applications. Because adrenomedullin exhibits low metabolic stability, enhancement of the plasma half-life is essential for peptide-based drug design. Fluorescently labeled ADM analogues synthesized by Fmoc/t-Bu solid phase peptide synthesis were used to analyze their enzymatic degradation and specific fragmentation pattern in human blood plasma. The determination of important cleavage sites allowed the development of selectively modified peptides in a rational approach. By combination of palmitoylation, lactam-bridging, and Nα-methylation, ADM analogues protected from enzymatic cleavage in human blood were developed and revealed an explicitly elongated half-life of 5 days in comparison to the wild-type in vitro. This triple-modification did not alter the selectivity of the analogues at the AM1 receptor, highlighting their potential for therapeutic applications.

[Political issues in internal medicine in Europe]. / Zur Situation der Inneren Medizin in Europa Ein Positionspapier der Europäischen Föderation für Innere Medizin.

What will be the future of Internal Medicine in Europe? Because of rapidly growing concerns regarding the position of Internal Medicine in many European countries, the European Federation of Internal Medicine (EFIM) has established a working group to analyze the situation. Being well aware of the variation of working practices in the different countries, the members of the group used an "all-European" approach to answer the following questions: -- Are there problems for Internal Medicine, what problems and why? -- Why do health care systems of the European countries need Internal Medicine? -- Why do the patients need Internal Medicine? -- What needs to be done? Internal Medicine is the modern, clinical and scientific medical discipline taking care of adult patients with one or more complex, acute or chronic illnesses. Internal Medicine is the cornerstone of integrated health care delivery service that is needed today. Decision-makers in politics and hospitals, insurers, journalists and the general public need a better understanding of what Internal Medicine can offer to the health care systems and to the individual patient.

[The critical incident reporting system (CIRS) as a measure to improve quality in medicine]. / Das Critical Incident Reporting System (CIRS) als Mittel zur Qualitätsverbesserung in der Medizin.

It may be seen as regrettable that a measure which is suitable for improvement of quality in medicine is broadly discussed only in the context of risk avoidance. The system of reporting adverse events (incidents), known under its internationally used term CIRS, is based on the observation that there is a close correlation between the occurrence of severe incidents with consequences and milder incidents or near misses without consequences. By avoiding mild incidents the severe incidents will automatical also be reduced. In contrast to a classic analysis of mistakes and errors the consequence itself only plays a minor role with CIRS. In Germany mistakes are usually seen under the aspects of a personal responsibility and they are prone to sanctions. But only when mistakes are accepted as occurring everywhere and with everybody and when they are regarded under the aspect of how to be avoided in future the necessary transparency can grow and an open dealing with mistakes can arise. This enables analyses with the only goal of quality improvement by avoidance of mistakes.

Complementary and alternative drug therapy versus science-oriented medicine.

This opinion deals critically with the so-called complementary and alternative medical (CAM) therapy on the basis of current data. From the authors' perspective, CAM prescriptions and most notably the extensive current endeavours to the "integration" of CAM into conventional patient care is problematic in several respects. Thus, several CAM measures are used, although no specific effects of medicines can be proved in clinical studies. It is extensively explained that the methods used in this regard are those of evidence-based medicine, which is one of the indispensable pillars of science-oriented medicine. This standard of proof of efficacy is fundamentally independent of the requirement of being able to explain efficacy of a therapy in a manner compatible with the insights of the natural sciences, which is also essential for medical progress. Numerous CAM treatments can however never conceivably satisfy this requirement; rather they are justified with pre-scientific or unscientific paradigms. The high attractiveness of CAM measures evidenced in patients and many doctors is based on a combination of positive expectations and experiences, among other things, which are at times unjustified, at times thoroughly justified, from a science-oriented view, but which are non-specific (context effects). With a view to the latter phenomenon, the authors consider the conscious use of CAM as unrevealed therapeutic placebos to be problematic. In addition, they advocate that academic medicine should again systematically endeavour to pay more attention to medical empathy and use context effects in the service of patients to the utmost. The subsequent opinion discusses the following after an introduction to medical history: the definition of CAM; the efficacy of most common CAM procedures; CAM utilisation and costs in Germany; characteristics of science-oriented medicine; awareness of placebo research; pro and contra arguments about the use of CAM, not least of all in terms of aspects related to medical ethics.

ROMPgel-supported triphenylphosphine with potential application in parallel synthesis.

[reaction: see text] ROMPgel-supported triphenylphosphine was synthesized in three steps (67%) from norbornadiene, 4-bromoiodobenzene, and chlorodiphenylphosphine. The supported reagent has a high loading (2.5 mmol/g) and favorable swelling properties in organic solvents. It has been utilized for the conversion of alcohols to halides, the reduction of ozonides, and the isomerization of alpha,beta-acetylenic esters and in the Staudinger reaction. In general, filtration of the resin from the reaction mixtures and evaporation gave the corresponding products in high yield and purity.

[Influence of the reimbursement system on medical quality]. / Einfluss von Vergütungssystemen auf die medizinische Qualität.

BACKGROUND: The relationship between reimbursement for medical care and the quality of medicine is mostly discussed if there are warnings about underuse as a consequence of underpayment. By various examples it can be illustrated that not only a lack of services but also an overuse of medical care may be hazardous and reduce quality in medicine. This relates to the risk, which is part of each medical intervention. PRESENT SITUATION: The introduction of the Diagnosis Related Groups (DRGs) in Germany is at present mostly discussed under the aspect of a possible risk of underuse. On the other hand, there are chances for the quality of medicine as a result from a lean diagnostic and therapy, which will be the consequence of economic changes induced by the DRGs. A guideline-oriented medicine will often avoid unnecessary procedures and thereby improve the quality of medical services. CONCLUSION: Loss of quality and improvement of quality arise in the field of medicine from overuse as well as from underuse. Most important for an optimal quality is a quantitatively appropriate treatment. In general, we observe that medical decisions are more and more oriented on economic frames. It has to be observed during forthcoming years to what extent ethical problems arise by this situation.

A Surprising Solid-Phase Effect: Development of a Recyclable "Traceless" Linker System for Reactions on Solid Support.

Triazenes as "traceless" linkers for solid-phase synthesis have been utilized for the attachment of arenes to a solid support and yield the corresponding products after various organometallic reactions (Heck reaction and asymmetric dihydroxylation, see the reaction scheme) and cycloadditions (Diels-Alder reaction). The triazene linker is distinguished by its accessibility, thermal robustness, and capability to undergo regeneration.