Euthanasie: une éthique de la transgression

Une éthique de la transgression ne signifiera jamais une banalisation juridique. Je me propose de présenter et de discuter ici les développements récents de la question de l'euthanasie active directe dans le monde francophone, à partir des propositions émises en Suisse et en France notamment, mais aussi, dans une moindre mesure, en Belgique. Puis, de procéder à quelques clarifications conceptuelles au sujet des notions de légali- sation et de dépénalisation. Ma réflexion se concentrera enfin sur le thème de la trans- gression, un thème qui apparaît en général comme opposé à l'idée même de l'éthique, et notamment de l'éthique chrétienne. Je m'efforcerai de montrer au contraire que la transgression, dans son caractère exceptionnel, représente une possibilité à la fois très forte et tout à fait plausible du courage et de la véracité; je présupposerai, sans le déve- lopper ici, que l'appel à ces deux valeurs éthiques peut se réclamer à bien des titres de l'esprit de l'Evangile.

Schwangerschaftsassoziierte Lebererkrankungen [Pregnancy-associated liver diseases]

Lebererkrankungen treten in der Schwangerschaft selten auf, können jedoch für Mutter und Kind dramatische Folgen haben, wenn sie nicht rechtzeitig erkannt werden. Prinzipiell unterscheidet man schwangerschaftsspezifische Lebererkrankungen von interkurrierenden Lebererkrankungen während der Schwangerschaft. Zu ersteren gehören die hepatischen Manifestationen der Hyperemesis gravidarum, die intrahepatische Schwangerschaftscholestase, die Leberbeteiligung bei Präeklampsie bzw. Eklampsie inkl. HELLP-Syndrom und die akute Schwangerschaftsfettleber. Die Differentialdiagnose schwangerschaftsassoziierter Lebererkrankungen basiert auf der Anamnese (Stadium der Schwangerschaft), der Klinik, wenigen Laboruntersuchungen und einer Ultrasonographie als primärem bildgebendem Verfahren. Die Behandlung der intrahepatischen Schwangerschaftscholestase mit Ursodeoxycholsäure verbessert den Pruritus und die mütterlichen Leberwerte. Eine engmaschige Überwachung der Schwangerschaft bleibt jedoch unabdingbar. Beim HELLP-Syndrom und der akuten Schwangerschaftsfettleber ist die rasche Entbindung anzustreben. Vorbestehende Lebererkrankungen bedürfen in der Schwangerschaft einer intensivierten Kontrolle. While liver diseases are a rare occurrence in pregnancy, they may have dramatic implications for mother and child if not detected in good time. A distinction is drawn between pregnancy-specific liver diseases and intercurrent liver diseases during pregnancy. The former include hepatic manifestations of hyperemesis gravidarum, intrahepatic cholestasis of pregnancy, hepatic involvement in preeclampsia or eclampsia, including the HELLP syndrome, and acute fatty liver of pregnancy. Differential diagnosis of pregnancy-associated liver disorders is based on history (stage of pregnancy), clinical findings, a few laboratory tests and ultrasound as the primary imaging technique. Treatment of intrahepatic cholestasis of pregnancy with ursodeoxycholic acid improves pruritus and maternal liver tests. Close monitoring of pregnancy remains however indispensable. In HELLP syndrome and acute fatty liver of pregnancy the aim should be rapid delivery. Preexisting liver diseases require intensified monitoring during pregnancy.

Switch-peptides: From conformational studies to Alzheimer's disease

Studies on designed peptides that exhibit high tendencies for medium-induced conformational transitions have recently attracted much attention because structural changes are considered as molecular key processes in degenerative diseases. The experimental access to these events has been limited so far mainly due to the intrinsic tendency of the involved polypeptides for self-association and aggregation, e.g. amyloid P plaque formation, thought to be at the origin of Alzheimer's disease. We have developed a new concept termed 'switch-peptides' which allows the controlled onset of polypeptide folding and misfolding in vitro and in vivo, starting from a soluble, non-toxic precursor molecule. As a major feature, the folding process is initiated by enzyme-triggered N,O-acyl migrations restoring the native peptide backbone in situ. As the folding is set off in the moment of creating the bioactive molecule ('in statu nascendi', ISN), our concept allows for the first time the investigation of the early steps of protein misfolding as relevant in degenerative diseases, opening new perspectives for the rational design of therapeutically relevant compounds.

Donors/recipients representations about living-kidney donation : P-527

Living-kidney donation offers an option to patients awaiting renal transplantation. Representations about giving-receiving are explored retrospectively in a qualitative study. Questionnaires with open questions were sent to thirty donor-recipient dyads. Interviews were also conducted, during which participants were invited to propose an image representing donation. Thematic analysis was performed on the questionnaires (twenty-nine donors; twenty-five recipients), and on the comments of ten images selected by five donors and five recipients. Percentages are given regarding each part (donors; recipients). In the questionnaires, life (34.5%; 12%), love (27.6%; 40%), quality of life (27.6%; 8%) and generosity (6.9%; 24%) are common grounds regarding giving-a-kidney. Obviousness, hope, personal benefits or duty are expressed by donors. Recipients explain donation through emphatic sentences, qualify it as a gift or refer to the donor's courage or risk-taking. Regarding receiving-a-kidney, life (31%; 60%), gift (10.3%; 28%) and debt (3.4%; 4%) are common grounds. Donors refer to generosity or love. Quality of life, donor's risk-taking or emphatic sentences are characteristic of recipients, who highlight that nobody had to die. Preliminary data on the comments of the images underline that live-donation represents life and love. Mutual help, sharing-act, obviousness and personal benefits are expressed by donors. Recipients use emphatic sentences or refer to quality of life, gift or the difficulty to accept donation. Life and love are common grounds in live-donation. Improvement in quality of life is underlined by recipients, who stress the donor's courage or risk-taking. Donors describe donation as obvious, sometimes accompanied by personal benefits. Feelings of duty (donors) and of debt (recipients) are less discussed. Representations about giving and receiving differ between donors and recipients. These data show the specificity of each perspective. This analysis provides valuable information in order to adapt individual or dyad psychological support in live-donation.

Characterization of a selective antagonist of neuropeptide Y at the Y2 receptor. Synthesis and pharmacological evaluation of a Y2 antagonist.

Neuropeptide Y (NPY) is a potent inhibitor of neurotransmitter release through the Y2 receptor subtype. Specific antagonists for the Y2 receptors have not yet been described. Based on the concept of template-assembled synthetic proteins we have used a cyclic template molecule containing two beta-turn mimetics for covalent attachment of four COOH-terminal fragments RQRYNH2 (NPY 33-36), termed T4-[NPY(33-36)]4. This structurally defined template-assembled synthetic protein has been tested for binding using SK-N-MC and LN319 cell lines that express the Y1 and Y2 receptor, respectively. T4-[NPY(33-36)]4 binds to the Y2 receptor with high affinity (IC50 = 67.2 nM) and has poor binding to the Y1 receptor. This peptidomimetic tested on LN319 cells at concentrations up to 10 microM shows no inhibitory effect on forskolin-stimulated cAMP levels (IC50 for NPY = 2.5 nM). Furthermore, we used confocal microscopy to examine the NPY-induced increase in intracellular calcium in single LN319 cells. Preincubation of the cells with T4-[NPY(33-36)]4 shifted to the right the dose-response curves for intracellular mobilization of calcium induced by NPY at concentrations ranging from 0.1 nM to 10 microM. Finally, we assessed the competitive antagonistic properties of T4-[NPY(33-36)]4 at presynaptic peptidergic Y2 receptors modulating noradrenaline release. the compound T4-[NPY(33-36)]4 caused a marked shift to the right of the concentration-response curve of NPY 13-36, a Y2-selective fragment, yielding a pA2 value of 8.48. Thus, to our best knowledge, T4-[NPY(33-36)]4 represents the first potent and selective Y2 antagonist.

Temozolomide: a milestone in neuro-oncology and beyond?

Temozolomide (Temodal, Temodar), an imidazol derivative, is a second-generation alkylating agent. The orally available prodrug with the capacity of crossing the blood-brain barrier received accelerated US FDA approval in 1999. Three pivotal Phase II trials showed modest activity in the treatment of recurrent anaplastic astrocytoma glioblastoma. In 2005, the FDA and the European Agency for the Evaluation of Medicinal Products approved temozolomide for use in newly diagnosed glioblastoma, in conjunction with radiotherapy, based on an European Organisation for Research and Treatment of Cancer/National Cancer Institute of Canada Phase III trial. The adverse events associated with temozolomide are mild-to-moderate and generally predictable; the most serious are noncumulative and reversible myelosuppression and, in particular, thrombocytopenia, which occurs in less than 5% of patients. Continuous temozolomide administration is associated with profound CD4-selective lymphocytopenia. Molecular studies have suggested that the benefit of temozolomide chemotherapy is restricted to patients whose tumors have a methylated methylguanine methyltransferase gene promotor and are thus unable to repair some of the chemotherapy-induced DNA damage. Temozolomide is under investigation for other disease entities, in particular lower-grade glioma, brain metastases and melanoma.

A template-assembled synthetic protein surface mimetic of the von Willebrand factor A1 domain inhibits botrocetin-induced platelet aggregation.

Platelet adhesion, the initial step of platelet activation, is mediated by the interaction of von Willebrand factor (VWF) with its platelet receptor, the GPIb-IX complex. The binding of VWF to GPIb-IX is induced either by increased shear stress or by exogenous modulators, such as botrocetin. At a molecular level, this interaction takes place between the A1 domain of VWF and the GPIb alpha chain of the GPIb-IX complex. We report here the design and functional characteristics of a VWF template-assembled synthetic protein (TASP), a chimeric four-helix-bundle TASP scaffold mimicking the surface of the A1 domain. Twelve residues located on helices alpha 3 and alpha 4 in the native A1 domain were grafted onto a surface formed by two neighboring helices of the TASP. VWF TASP was found to inhibit specifically botrocetin-induced platelet aggregation and to bind both botrocetin and GPIb alpha. However, in contrast to the native A1 domain, VWF TASP did not bind simultaneously to both ligands. Modeling studies revealed that the relative orientation of the alpha helices in VWF TASP led to a clash of bound botrocetin and GPIb alpha. These results demonstrate that a chimeric four-helix-bundle TASP as a scaffold offers a suitable surface for presenting crucial residues of the VWF A1 domain; the potential of the TASP approach for de novo protein design and mimicry is thereby illustrated.

A modular magnetic anastomotic device for minimally invasive digestive anastomosis: proof of concept and preliminary data in the pig model.

BACKGROUND: The aim of our study was to assess the feasibility of minimally invasive digestive anastomosis using a modular flexible magnetic anastomotic device made up of a set of two flexible chains of magnetic elements. The assembly possesses a non-deployed linear configuration which allows it to be introduced through a dedicated small-sized applicator into the bowel where it takes the deployed form. A centering suture allows the mating between the two parts to be controlled in order to include the viscerotomy between the two magnetic rings and the connected viscera. METHODS AND PROCEDURES: Eight pigs were involved in a 2-week survival experimental study. In five colorectal anastomoses, the proximal device was inserted by a percutaneous endoscopic technique, and the colon was divided below the magnet. The distal magnet was delivered transanally to connect with the proximal magnet. In three jejunojejunostomies, the first magnetic chain was injected in its linear configuration through a small enterotomy. Once delivered, the device self-assembled into a ring shape. A second magnet was injected more distally through the same port. The centering sutures were tied together extracorporeally and, using a knot pusher, magnets were connected. Ex vivo strain testing to determine the compression force delivered by the magnetic device, burst pressure of the anastomosis, and histology were performed. RESULTS: Mean operative time including endoscopy was 69.2 ± 21.9 min, and average time to full patency was 5 days for colorectal anastomosis. Operative times for jejunojejunostomies were 125, 80, and 35 min, respectively. The postoperative period was uneventful. Burst pressure of all anastomoses was ≥ 110 mmHg. Mean strain force to detach the devices was 6.1 ± 0.98 and 12.88 ± 1.34 N in colorectal and jejunojejunal connections, respectively. Pathology showed a mild-to-moderate inflammation score. CONCLUSIONS: The modular magnetic system showed enormous potential to create minimally invasive digestive anastomoses, and may represent an alternative to stapled anastomoses, being easy to deliver, effective, and low cost.