Entwicklung von neuen Radiomarkierungsverfahren und deren Anwendung zur Synthese von Radiotracern für die Positronen-Emissions-Tomographie

In den letzten 30 Jahren hat sich die Positronen Emissions Tomographie (PET) zu einem der wichtigsten Instrumente in der klinischen Diagnostik entwickelt. Neben den ständigen technischen Verbesserungen verdankt die PET ihren klinischen Stellenwert vor allem dem ihr inhärenten Potenzial, physiologische und biochemische Prozesse auf molekularer Ebene und in Echtzeit darzustellen. Aufgrund der wachsenden Zahl neuer und krankheitsspezifischer Radiotracer nimmt sie auch auf dem Gebiet der Wirkstoffentwicklung sowie beim Monitoring von pharmakologischen Interventionen eine immer wichtigere Rolle ein. Grundlegend hierfür ist einerseits das intelligente Design innovativer und selektiver molekularer Sonden mit der Fähigkeit zur Visualisierung molekularer Targets, die in physiologischen und pathophysiologischen Prozessen involviert sind und andererseits die Entwicklung der dafür notwendigen fortschrittlichen Markierungsstrategien. Letzteres ist zentraler Bestandteil der radiochemischen Grundlagenforschung und Hauptgegenstand dieser kumulativen Promotionsarbeit, in dessen Rahmen ein neues „minimalistisches“ Protokoll zur Radiofluorierung ausgearbeitet wurde. Die Entwicklung der sog. „minimalistische“ Methode ermöglicht eine vereinfachte und zeitsparende Herstellung von unterschiedlichsten 18F-markierten Verbindungen, da sie weder der azeotropen Trocknung noch des Zusatzes einer Base oder anderer Additive bedarf. Das neue Radiomarkierungsverfahren umfasst eine direkte Elution von 18F- mittels alkoholischer Lösung der Ammonium-, Diaryliodonium- oder Triarylsulfoniumsalz Vorläufern. Nach Entfernung des Alkohols wird das resultierende [18F]Fluoridsalz in einem geeigneten Lösungsmittel erhitzt. Die hohe Effizienz der auf der „minimalistischen“ Methode basierenden Synthese bietet somit auch einen schnellen Zugang zu 18F-markierten Fluorbenzaldehyden ([18F]FBAs) in großen Aktivitätsmengen, was einen entscheidenden Vorteil für die Entwicklung neuer Markierungsmethoden mit Hilfe dieses Radiomarkierungsbausteins darstellt. Darauf aufbauend wurde, ausgehend von [18F]FBA, auf der Basis der Seyferth-Gilbert Homologisierung, ein innovatives Verfahren zur Synthese von bisher unbekannten 18F-markierten Fluorarylacetylenen entwickelt. Hierdurch konnten über Cycloadditions- und Kreuzkupplungsreaktionen unterschiedliche radiomarkierte Modellverbindungen sowie PET-Tracer hergestellt und somit die Vielseitigkeit der neuen radiomarkierten Synthone aufgezeigt werden. Die durch die „minimalistische“ Methode gesteigerte Effizienz der Synthese von [18F]FBA ermöglicht es ebenfalls, den bereits in der Literatur bekannten Markierungsbaustein C-(4-[18F]Fluorphenyl)-N-phenylnitron [18F]FPPN in ausreichenden Mengen zu produzieren und für die zielgerichtete Synthese diverser radiofluorierter -Lactame über die Kinugasa-Reaktion einzusetzen. Mit dem Erhalt der radiofluorierten β-Lactam-Peptid und -Protein-Konjugate in hohen radiochemischen Ausbeuten unter sehr milden Bedingungen, konnte die Eignung der Kinugasa-Reaktion als neues und leistungsstarkes Radiofluorierungsverfahren eindrucksvoll demonstriert werden. 

Die laesio enormis und der dolus re ipsa heute: die Verschuldensfrage

The mediaeval interpreters of Roman law have worked out the dolus re ipsa-concept to explain the mysterious laesio enormis (C. 4.44.2 [a. 285]). The inequality in exchange has been supposed then to be a result of malicious undertaking, for which paradoxically, no one was personally liable (Ulp. 45 ad Sab. D. 45.1.36). In course of time, the incorporation of laesio enormis into the scheme of dolus turned into a presumption of a malicious act on the part of the enriched party, even though, the laesio enormis is free from subjective criteria. It is astonishing how little the dolus re ipsa is discussed, although the modern paradigm for correcting inequality in exchange is based on same assumptions. This ‘Wiederkehr der Rechtsfigur’ certainly deserves more attention.

Hydroalumination of seleno acetylenes: a versatile generation and reactions of alpha-aluminate vinyl selenide intermediates in the highly regio and stereoselective synthesis of telluro(seleno)ketene acetals

The hydroalumination of butylseleno acetylenes with DIBAL-H followed by addition of n-butyllithium generated in situ the (Z)-butylseleno vinyl alanates intermediates which were captured with C(4)H(9)TeBr furnishing the (E)-telluro(seleno)ketene acetals exclusively. The isomers with opposite stereochemistry (Z)-telluro(seleno)ketene acetals were obtained by the reduction of phenylseleno acetylenes with lithium di-(isobutyl)-n-butyl aluminate hydride (Zweifel's reagent) followed by reaction of (E)-phenylseleno vinyl alanates intermediates with C(4)H(9)TeBr. (c) 2008 Elsevier Ltd. All rights reserved.

Distribution of neutral prilocaine in a phospholipid bilayer: Insights from molecular dynamics simulations

In this work, we report a 20-ns constant pressure molecular dynamics simulation of prilocaine (PLC), in amine-amide local anesthetic, in a hydrated liquid crystal bilayer of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine. The partition of PLC induces the lateral expansion of the bilayer and a concomitant contraction in its thickness. PLC molecules are preferentially found in the hydrophobic acyl chains region, with a maximum probability at similar to 12 angstrom from the center of the bilayer (between the C(4) and C(5) methylene groups). A decrease in the acyl chain segmental order parameter, vertical bar S-CD vertical bar, compared to neat bilayers, is found, in good agreement with experimental H-2-NMR studies. The decrease in vertical bar S-CD vertical bar induced by PLC is attributed to a larger accessible volume per lipid in the acyl chain region. (C) 2008 Wiley Periodicals, Inc.

Analysis of the isomerism effect on the mutual solubilities of bis(trifluoromethylsulfonyl)imide-based ionic liquids with water

The knowledge of the liquid-liquid equilibria (LLE) between ionic liquids (ILs) and water is of utmost importance for environmental monitoring, process design and optimization. Therefore, in this work, the mutual solubilities with water, for the ILs combining the 1-methylimidazolium, [C(1)im](+); 1-ethylimidazolium, [C(2)im](+); 1-ethyl-3-propylimidazolium, [C(2)C(3)im](+); and 1-butyl-2,3-dimethylimidazolium, [C(4)C(1)C(1)im](+) cations with the bis(trifluoromethylsulfonyl)imide anion, were determined and compared with the isomers of the symmetric 1,3-dialkylimidazolium bis(trifluoromethylsulfonyl)imide ([C(n)C(n)im][NTf2], with n=1-3) and of the asymmetric 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C(n)C(1)im][NTf2], with n = 2-5) series of ILs. The results obtained provide a broad picture of the impact of the IL cation structural isomerism, including the number of alkyl side chains at the cation, on the water-IL mutual solubilities. Despite the hydrophobic behaviour associated to the [NTf2](-) anion, the results show a significant solubility of water in the IL-rich phase, while the solubility of ILs in the water-rich phase is much lower. The thermodynamic properties of solution indicate that the solubility of ILs in water is entropically driven and highly influenced by the cation size. Using the results obtained here in addition to literature data, a correlation between the solubility of [NTf2]-based ILs in water and their molar volume, for a large range of cations, is proposed. The COnductor like Screening MOdel for Real Solvents (COSMO-RS) was also used to estimate the LLE of the investigated systems and proved to be a useful predictive tool for the a priori screening of ILs aiming at finding suitable candidates before extensive experimental measurements.

Photoluminescent materials based on PMMA and a highly-emissive octahedral molybdenum metal cluster complex

Materials that combine photoluminescence, optical transparency and facile processability are of high importance in many applications. This article reports on the development of photoluminescent poly(methyl methacrylate) materials based on novel highly emissive anionic molybdenum cluster complex [{Mo6I8}(OTs)6]2- (where OTs- is the p-toluenesulfonate ion). The materials were obtained by both solution and bulk copolymerisation of methyl methacrylate and (dMDAEMA)2[{Mo6I8}(OTs)6], where dMDAEMA+ is the polymerisable cation [2-(methacryloyloxy)ethyl]dimethyl-dodecylammonium. Evaluation of the resultant hybrid materials showed that one could combine the excellent photoluminescent properties of the cluster complex with the transparency and processability of PMMA.

The preparation of a certified reference material of polar pesticides in freeze-dried water (CRM 606)

The preparation of a certified reference material of polar pesticides in freeze-dried water is described. The pesticides selected were atrazine, simazine, carbaryl, propanil, linuron, fenamiphos and permethrin which were added to 6000 litres of tap water at 50–80 μg · L–1 (200–320 μg · L–1 for permethrin) level in presence of NaCl (2.5 g · L–1) prior lyophilization. After the freeze-drying process the residue was rehomogenized, filled into amber glass bottles and stored at –20 °C, +4 °C and +20 °C. All pesticides were determined by HPLC/diode array detector, except permethrin which was determined by GC/ECD. The results obtained for atrazine, simazine, carbaryl, propanil, linuron and fenamiphos showed no within- or between-bottle inhomogeneity, however the material was non-homogeneous for permethrin and therefore this was withdrawn from further studies. With respect to the stability for over one year, all pesticides were stable at –20 °C. At +4 °C all pesticides were stable for at least 9 months and at +20 °C the stability was demonstrated only during the first month of storage. The content (mass fractions) of atrazine, simazine, carbaryl, propanil and linuron in freeze-dried water (CRM 606) was certified by an interlaboratory testing and a certification campaign.

β-lactams from their structural features to their biological applications

β-lactam compounds represent an important class of four-membered cyclic amides (azetidin-2-ones) thanks to their valuable and varied biological activities. The presence of a β-lactam ring in a series of bioactive molecules targeting different proteins, allows us to consider the azetidin-2-one a privileged structure. The constrained four-membered cyclic amide could easily undergo ring-opening reactions by nucleophilic residues in the active sites of enzymes and this is the mechanism suggested for antibacterial activity; moreover, the rigid core structure could favour and actually enhance directional noncovalent bonding for an effective ligand−receptor recognition. Nowadays monocyclic β-lactams are known as anticancer, antidiabetic, anti-tubercular, anti-inflammatory agents and as ligands of integrin receptors. In order to consider different facets of 4-azetidin-2-ones, this theis will be divided into two sections: the first one will be dedicated to the design, synthesis and characterization of biological active β-lactams (new β-lactam based integrin ligands and their different applications and novel N-thio-alkyl substituted azetidinones for the treatment of Tuberculosis); the second one instead, will be based on two projects which consider two different proprieties of β-lactams: stereochemistry, evaluated by biocatalytic methods and reactivity at C-4 position. In the first case we want to obtain enantiomerically pure 4-acetoxy-2-azetidinone, useful for synthesis of stereo-chemically defined bioactive β-lactams, while in the second case we want to study in which conditions the nucleophilic substitutions occur. A final section will be instead dedicated to the research project conducted in Philochem AG, Zurich, under the supervision of Prof. Dario Neri and Dr. Samuele Cazzamalli, based on the study of new cleavable disulfide linkers for small molecule drug conjugates targeting Fibroblast activation protein (FAP).

Ricerche in materia di 'ius emphyteuticum' sulle 'meliorationes, quae graeco vocabulo emponemata dicuntur'

Le presenti ricerche indagano la disciplina delle «meliorationes, quae graeco vocabulo emponemata dicuntur» nell’ambito dell’enfiteusi privata giustinianea, pervenendo, a seguito della ricostruzione della nozione di «emponemata», a una interpretazione di C. 4.66.3 (a. 530) secondo la quale questa costituzione non implicherebbe – anche in ragione del confronto testuale con Nov. 64 (a. 538), in materia di «misthosis» – una deroga al principio «superficies solo cedit» e – con riferimento alla fattispecie della loro alienazione – farebbe del termine «meliorationes» un uso condizionale e metonimico, volto a enucleare – nell’ambito delle diverse possibilità di trasferimento «inter vivos» dell’enfiteusi – il caso (oggetto di speciale normazione) della «venditio» per la sola ipotesi in cui sul fondo enfiteutico fossero intervenute «meliorationes» tali da poter essere qualificate come «emponemata».

Seawater carbonate chemistry and net photosynthesis, C/N ratio, growth rate, size of Ostreococcus tauri in a laboratory experiment

Phytoplankton are the basis of marine food webs, and affect biogeochemical cycles. As CO2 levels increase, shifts in the frequencies and physiology of ecotypes within phytoplankton groups will affect their nutritional value and biogeochemical function. However, studies so far are based on a few representative genotypes from key species. Here, we measure changes in cellular function and growth rate at atmospheric CO2 concentrations predicted for the year 2100 in 16 ecotypes of the marine picoplankton Ostreococcus. We find that variation in plastic responses among ecotypes is on par with published between-genera variation, so the responses of one or a few ecotypes cannot estimate changes to the physiology or composition of a species under CO2 enrichment. We show that ecotypes best at taking advantage of CO2 enrichment by changing their photosynthesis rates most should increase in relative fitness, and so in frequency in a high-CO2 environment. Finally, information on sampling location, and not phylogenetic relatedness, is a good predictor of ecotypes likely to increase in frequency in this system.

BALB/c Mice Infected with Antimony Treatment Refractory Isolate of Leishmania braziliensis Present Severe Lesions due to IL-4 Production

Background: Leishmania braziliensis is the main causative agent of cutaneous leishmaniasis in Brazil. Protection against infection is related to development of Th1 responses, but the mechanisms that mediate susceptibility are still poorly understood. Murine models have been the most important tools in understanding the immunopathogenesis of L. major infection and have shown that Th2 responses favor parasite survival. In contrast, L. braziliensis-infected mice develop strong Th1 responses and easily resolve the infection, thus making the study of factors affecting susceptibility to this parasite difficult. Methodology/Principal Findings: Here, we describe an experimental model for the evaluation of the mechanisms mediating susceptibility to L. braziliensis infection. BALB/c mice were inoculated with stationary phase promastigotes of L. braziliensis, isolates LTCP393(R) and LTCP15171(S), which are resistant and susceptible to antimony and nitric oxide (NO), respectively. Mice inoculated with LTCP393(R) presented larger lesions that healed more slowly and contained higher parasite loads than lesions caused by LTCP15171(S). Inflammatory infiltrates in the lesions and production of IFN-gamma, TNF-alpha, IL-10 and TGF-beta were similar in mice inoculated with either isolate, indicating that these factors did not contribute to the different disease manifestations observed. In contrast, IL-4 production was strongly increased in LTCP393(R)-inoculated animals and also arginase I (Arg I) expression. Moreover, anti-IL-4 monoclonal antibody (mAb) treatment resulted in decreased lesion thickness and parasite burden in animals inoculated with LTCP393(R), but not in those inoculated with LTCP15171(S). Conclusion/Significance: We conclude that the ability of L. braziliensis isolates to induce Th2 responses affects the susceptibility to infection with these isolates and contributes to the increased virulence and severity of disease associated with them. Since these data reflect what happens in human infection, this model could be useful to study the pathogenesis of the L. braziliensis infection, as well as to design new strategies of therapeutic intervention.

Photosynthesis and water relations of well-watered orange plants as affected by winter and summer conditions

The aim of this study was to evaluate how the summer and winter conditions affect the photosynthesis and water relations of well-watered orange trees, considering the diurnal changes in leaf gas exchange, chlorophyll (Chl) fluorescence, and leaf water potential (I) of potted-plants growing in a subtropical climate. The diurnal pattern of photosynthesis in young citrus trees was not significantly affected by the environmental changes when compared the summer and winter seasons. However, citrus plants showed higher photosynthetic performance in summer, when plants fixed 2.9 times more CO(2) during the diurnal period than in the winter season. Curiously, the winter conditions were more favorable to photosynthesis of citrus plants, when considering the air temperature (< 29 A degrees C), leaf-to-air vapor pressure difference (< 2.4 kPa) and photon flux density (maximum values near light saturation) during the diurnal period. Therefore, low night temperature was the main environmental element changing the photosynthetic performance and water relations of well-watered plants during winter. Lower whole-plant hydraulic conductance, lower shoot hydration and lower stomatal conductance were noticed during winter when compared to the summer season. In winter, higher ratio between the apparent electron transport rate and leaf CO(2) assimilation was verified in afternoon, indicating reduction in electron use efficiency by photosynthesis. The high radiation loading in the summer season did not impair the citrus photochemistry, being photoprotective mechanisms active. Such mechanisms were related to increases in the heat dissipation of excessive light energy at the PSII level and to other metabolic processes consuming electrons, which impede the citrus photoinhibition under high light conditions.

The viability of three probiotic organisms grown with yoghurt starter cultures during storage for 21 days at 4 degrees C

This study investigated the viability of probiotic (Lactobacillus acidophilus LA5, Lactobacillus rhamnosus LBA and Bifidobacterium animalis subsp. lactis BL-04) in milk fermented with Lactobacillus delbrueckii subsp. bulgaricus LB340 and Streptococcus thermophilus TAO (yoghurt - Y). Each probiotic strain was grown separately in co-culture with Y and in blends of different combinations. Blends affected fermentation time(s), pH and firmness during storage at 4 degrees C. The product made with Y plus B. animalis subsp. lactis and L. rhamnosus had counts of viable cells at the end of shelf life that met the minimum required to achieve probiotic effect. However, L. acidophilus and L. delbrueckii subsp. bulgaricus were inhibited.

Spin states of C-60(3-) and C120On- (n=2, 3, 4) anions using electron spin transient nutation spectroscopy

Electron spin transient nutation (ESTN) experiments show that the spin multiplicity of the ground state of C-60(3-) in frozen solution is a doublet with S = 1/2. In purified samples, there is no evidence for excited states or other species with higher multiplicity. In the anions Of C120On- (n = 2, 3, 4), where the CW EPR experiments have shown that a mixture of species is present, ESTN experiments confirm that a doublet with S = 1/2 is associated with the 3- anion and triplets with S = 1 are associated with the 2- and 4- anions. A weak nutation peak attributable to m(s) = -1/2 1/2 transitions within a quartet state may arise from association of anions with spins of 1/2 and 1 in solute aggregates.

The effect of nutrient enrichment on growth, photosynthesis and hydraulic conductance of dwarf mangroves in Panama

1. Dwarf stands of the mangrove Rhizophora mangle L. are extensive in the Caribbean. We fertilized dwarf trees in Almirante Bay, Bocas del Toro Province, north-eastern Panama with nitrogen (N) and phosphorus (P) to determine (1) if growth limitations are due to nutrient deficiency; and (2) what morphological and/or physiological factors underlie nutrient limitations to growth. 2. Shoot growth was 10-fold when fertilized with P and twofold with N fertilization, indicating that stunted growth of these mangroves is partially due to nutrient deficiency. 3. Growth enhancements caused by N or P enrichment could not be attributed to increases in photosynthesis on a leaf area basis, although photosynthetic nutrient-use efficiency was improved. The most dramatic effect was on stem hydraulic conductance, which was increased sixfold by P and 2.5-fold with N enrichment. Fertilization with P enhanced leaf and stem P concentrations and reduced C : N ratio, but did not alter leaf damage by herbivores. 4. Our findings indicate that addition of N and P significantly alter tree growth and internal nutrient dynamics of mangroves at Bocas del Toro, but also that the magnitude, pattern and mechanisms of change will be differentially affected by each nutrient.