Aryl hydrocarbon receptor modulation by tuberculosis drugs impairs host defense and treatment outcomes

Animal science

The orofacial formalin test in mice re-visited - effects of formalin concentration, age, morphine and analysis method

Hintergrund und Ziele: Der in der Schmerzforschung etablierte Formalintest wurde am Mausorganismus erstmals im Versorgungsgebiet des Nervus trigeminus angewandt, um eine Basis für die Erforschung von Pathologien des trigeminalen Systems in dieser aufgrund der Knock-out-Technologie interessanten Spezies zu schaffen. Zielsetzung war es, eine für die Testung potentiell analgetischer Substanzen optimale Formalinkonzentration zu finden, zeitsparende Alternativen zur gängigen Messung des kumulativen Schmerzverhaltens und eine mögliche Altersabhängigkeit des Schmerz-induzierten Verhaltens zu prüfen. Methoden: In der ersten Versuchsreihe wurde die Wirkung von Formalin in Konzentrationen von 0,5%, 1%, 2,5%, 5%, 7,5%, 10% und 15% auf das Verhalten der Tiere untersucht. Der Einfluß von Morphin in Dosierungen von 1, 5 und 10 mg/kg auf das durch 2,5% Formalin induzierte Verhalten war Gegenstand der zweiten Versuchsreihe. Verhaltensunterschiede von Tieren im Alter von 6, 10, 15 und 20 Wochen nach Gabe von 2,5% Formalin untersuchten wir in der dritten Versuchsreihe. Für alle drei Versuchsreihen wurde das kumulative nozizeptive Verhalten in Sekunden bestimmt. Das nozizeptive und nicht-nozizeptive, sonstige Verhalten wurde zusätzlich auf der Basis eines Bewertungsscores erfasst, der in einminütigen Abständen ermittelt wurde. Beide Bewertungsmodi wurden für jedes Tier über einen Zeitraum von einer Stunde erhoben und bezüglich ihrer Reproduzierbarkeit und Effizienz miteinander verglichen. Ergebnisse: In der ersten Versuchsreihe war das kumulative Schmerzverhalten für sämtliche Gruppen mit Formalininjektion signifikant stärker ausgeprägt als in den Kontrollgruppen. Bei hohen Formalinkonzentrationen kam es zu keinem weiteren signifikanten Anstieg des kumulativen Schmerzverhaltens (Ceiling-Effekt). Der Score 3 für nozizeptives Verhalten („Kratzen der Injektionsstelle mit der Hinterpfote“) zeigte mit dem kumulativen Schmerzverhalten vergleichbare Ergebnisse. Die halbmaximale Formalinkonzentration (EC50) betrug für das kumulative Schmerzverhalten 2,7%, für den Score 3 des nozizeptven Verhaltens 3,4%. Morphin in einer Dosierung von 1, 5 und 10 mg/kg unterdrückte das kumulative nozizeptive Verhalten nach Formalininjektion um 18%, 93% bzw. 99,7%. Wiederum lieferte der Score 3 für nozizeptives Verhalten dem kumulativen Schmerzverhalten vergleichbare Ergebnisse. Altersabhängige Verhaltensänderungen wurden weder durch das kumulative Schmerzverhalten noch durch einen der Bewertungsscores nachgewiesen. Schlussfolgerungen: Der Formalintest im trigeminalen Innervationsgebiet der Maus stellt ein valides Modell für das Erzeugen und die Quantifizierung von länger anhaltendem, tonischem Schmerz dar, das auf Morphingabe sensibel reagiert. Geeignet sind mittlere Konzentrationen im Bereich der halbmaximalen Effektkonzentration (EC50). Die Bewertung des nozizeptiven Verhaltens in einminütigen Abständen ist eine zeitsparende Alternative zur kontinuierlichen Messung mit hoher Aussagekraft, mit deren Hilfe der Arbeitsaufwand pro Tier drastisch gesenkt werden kann.Aims: The formalin test, which is well established in the study of pain, was applied to the orofacial region of the mouse for the first time to provide a basis for the further investigation of pathologies in the trigeminal system of this species, which is especially interesting due to the development of transgenic knockout technology. The aim of our study was to find the formalin concentration which is most qualified for testing potentially analgesic drugs in the future and to examine time-saving alternatives for the measurement of pain currently used as well as possible age differences in nociception. Methods: In the first series of tests the effects of formalin concentrations of 0.5%, 1%, 2.5%, 5%, 7.5%, 10% and 15% on the animals’ behavior were tested. Subsequently, we examined the effects of morphine at doses of 1, 5 and 10 mg/kg on the nociceptive response induced by 2.5% formalin. Behavioral differences between mice aged 6, 10, 15 and 20 weeks after injection of 2.5% formalin were the subject of the third part of the experiment. The number of seconds the animals spent showing nociceptive behaviors was collected for any series of tests. Additionally, nociceptive as well as non-nociceptive behaviors were determined based on a score that was recorded once per minute. Continuous rating method and time-sampling method were each measured over a period of one hour for any mouse and were compared regarding reproducibility and efficiency. Results: The total amount of time spent with nociceptive behavior was significantly higher for mice of any of the formalin groups compared to those of the control groups. The highest formalin concentrations did not result in a further increase of nociceptive behavior (ceiling effect). The findings for score 3 of the nociceptive behavior (“scratching of injection site with the hindpaw”) were comparable with those obtained by means of the continuous rating method. The formalin concentration that lead to 50% of the maximum effect (EC50) was 2.7% and 3.4% for the continuous rating method and score 3 of nociceptive behavior, respectively. Morphine at doses of 1, 5 and 10 mg/kg after formalin injection suppressed the time spent with nociceptive behavior by 18%, 93% and 99.7%, respectively. Again, the score 3 of the nociceptive behavior was comparable to the continuous rating method. Age differences in behavior could not be verified either by the continuous rating method or by any score of nociceptive or non-nociceptive behaviors. Conclusions: The orofacial formalin test represents a valid model for generating and quantifying long-lasting, tonic pain in the mouse which is sensitive to the application of morphine. Middle-range formalin concentrations close to the EC50 value are suited best. The evaluation of nociceptive behaviors at an interval of one minute is a time-saving alternative to the continuous rating method which diminishes the amount of work drastically

Anion-pi Catalysis: Foldamers, Carbon Nanotubes and Electric Fields

To build new functional materials non-covalent interactions play a major role in today’s chemistry. They provide a large plethora of possibilities to mimic nature and create systems with functions or reactivities that could otherwise not be reached. In this PhD thesis unorthodox anion-π interactions were explored. NDI foldamers up to tetramers were designed synthesized and investigated for their stacking behavior. They were successfully employed in homogeneous catalysis of enolate additions to nitroolefins to prove that synergistic effects between π-π stacking and anion- π interactions exist and can give access to remarkable catalytic activities. Additionally, highly polarizable single- and multiwalled carbon nanotubes were applied in the same reaction. The synergy between polarizability along and between the tubes in multiwalled carbon nanotubes covalently and non-covalently functionalized with tertiary amines lead to unprecedented activities despite the heterogeneous nature of the systems. Finally attempts with surface catalysts polarized by electric fields were made

Lifetime broadening and impulsive generation of vibrational coherence triggered by ultrafast electron transfer

AbstractData presented in the article: 'Lifetime broadening and impulsive generation of vibrational coherence triggered by ultrafast electron transfer', by A. Aster, A.-B. Bornhof, S. Matile and E. Vauthe

Anion-π Catalysis of Diels-Alder Reactions

Among concerted cycloadditions, the Diels–Alder reaction is the grand old classic, which is usually achieved with acid catalysis. In this report, hydroxypyrones, oxa-, and thiazolones are explored because they provide access to anionic dienes. Their [4+2] cycloaddition with cyclic and acyclic dienophiles, such as maleimides and fumarates, affords bicyclic products with four new stereogenic centers. Bifunctional anion–π catalysts composed of amine bases next to the π surface of naphthalenediimides (NDIs) are shown to selectively stabilize the “open”, fully accessible anionic exo transition state on the π-acidic aromatic surface. Our results also include reactivities that are hard to access with conventional organocatalysts, such as the exo-specific and highly enantioselective Diels–Alder reaction of thiazolones and maleimides with complete suppression of the otherwise dominant Michael addition. With increasing π acidity of the anion–π catalysts, the rates, chemo-, diastereo-, and enantioselectivities increase consistently

IL-36/LXR axis modulates cholesterol metabolism and immune defense to Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) is a life-threatening pathogen in humans. Bacterial infection of macrophages usually triggers strong innate immune mechanisms, including IL-1 cytokine secretion. The newer member of the IL-1 family, IL-36, was recently shown to be involved in cellular defense against Mtb. To unveil the underlying mechanism of IL-36 induced antibacterial activity, we analyzed its role in the regulation of cholesterol metabolism, together with the involvement of Liver X Receptor (LXR) in this process. We report that, in Mtb-infected macrophages, IL-36 signaling modulates cholesterol biosynthesis and efflux via LXR. Moreover, IL-36 induces the expression of cholesterol-converting enzymes and the accumulation of LXR ligands, such as oxysterols. Ultimately, both IL-36 and LXR signaling play a role in the regulation of antimicrobial peptides expression and in Mtb growth restriction. These data provide novel evidence for the importance of IL-36 and cholesterol metabolism mediated by LXR in cellular host defense against Mtb

Rational Synthesis of 2‑Bromoporphyrins and 2,12-Dibromoporphyrins

Bromoporphyrins were prepared by the metal-mediated self-condensation of brominated 1-formyl­dipyrro­methanes. Depending on the conditions, Mg­(II)-2,12-dibromo­porphyrin and Mg­(II)-2-bromoporphyrin could be obtained in up to 11% and 17% isolated yield, respectively. Zn­(II) was also a viable templating metal. The positions of the bromine substituents were confirmed by 2D-NMR spectroscopic analysis and the X-ray crystal structure of a derivative. Suzuki and Sonogashira reactions of the bromoporphyrins yielded 2-substituted or 2,12-disubstituted porphyrins with red-shifted absorption and emission spectra. This method provides access to the minimalist core of β-mono- and β,β′-disubstituted porphyrins from readily available starting materials

IL-36/LXR axis modulates cholesterol metabolism and immune defense to Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) is a life-threatening pathogen in humans. Bacterial infection of macrophages usually triggers strong innate immune mechanisms, including IL-1 cytokine secretion. The newer member of the IL-1 family, IL-36, was recently shown to be involved in cellular defense against Mtb. To unveil the underlying mechanism of IL-36 induced antibacterial activity, we analyzed its role in the regulation of cholesterol metabolism, together with the involvement of Liver X Receptor (LXR) in this process. We report that, in Mtb-infected macrophages, IL-36 signaling modulates cholesterol biosynthesis and efflux via LXR. Moreover, IL-36 induces the expression of cholesterol-converting enzymes and the accumulation of LXR ligands, such as oxysterols. Ultimately, both IL-36 and LXR signaling play a role in the regulation of antimicrobial peptides expression and in Mtb growth restriction. These data provide novel evidence for the importance of IL-36 and cholesterol metabolism mediated by LXR in cellular host defense against Mtb