Characterization of the Active Site and Insight into the Binding Mode of the Anti-angiogenesis Agent Fumagillin to the Manganese(II)-Loaded Methionyl Aminopeptidase from \u3cem\u3eEscherichia coli\u3c/em\u3e

EPR spectra were recorded for methionine aminopeptidase from Escherichia coli (EcMetAP-I) samples (~2.5 mM) to which one and two equivalents of Mn(II) were added (the latter is referred to as [MnMn(EcMetAP-I)]). The spectra for each sample were indistinguishable except that the spectrum of [MnMn(EcMetAP-I)] was twice as intense. The EPR spectrum of [MnMn(EcMetAP-I)] exhibited the characteristic six-line g≈2 EPR signal of mononuclear Mn(II) with A av(55Mn)=9.3 mT (93 G) and exhibited Curie-law temperature dependence. This signal is typical of Mn(II) in a ligand sphere comprising oxygen and/or nitrogen atoms. Other features in the spectrum were observed only as the temperature was raised from that of liquid helium. The temperature dependences of these features are consistent with their assignment to excited state transitions in the S=1, 2 ... 5 non-Kramer’s doublets, due to two antiferromagnetically coupled Mn(II) ions with an S=0 ground state. This assignment is supported by the observation of a characteristic 4.5 mT hyperfine pattern, and by the presence of signals in the parallel mode consistent with a non-Kramers’ spin ladder. Upon the addition of the anti-angiogenesis agent fumagillin to [MnMn(EcMetAP-I)], very small changes were observed in the EPR spectrum. MALDI-TOF mass spectrometry indicated that fumagillin was, however, covalently coordinated to EcMetAP-I. Therefore, the inhibitory action of this anti-angiogenesis agent on EcMetAP-I appears to involve covalent binding to a polypeptide component at or near the active site rather than direct binding to the metal ions

Devices for Prevention of Atrial Tachyarrhythmias

Atrial fibrillation (AF) is the most frequent sustained cardiac arrhythmia in clinical practice and, although its importance has been underestimated even in recent years, we are now becoming aware of its clinical transcendence1,2,3. The classical treatment is pharmacological, but its efficacy is limited and it does have side effects4,5. Therefore, in recent years, there has been an increasing interest in other types of non-pharmacological treatments6,7. Physiologic cardiac pacing has proven to be more effective than VVI mode pacing to prevent the occurrence of AF during the follow-up of patients who have had a permanent pacemaker implanted 8,9,10. There are currently different lines of research that use different atrial pacing techniques to prevent and treat episodes of paroxysmal atrial fibrillation11,12. Techniques of multi-site pacing in the right atrium or both atria, new atrial pacing sites, prevention algorithms for paroxysmal atrial fibrillation episodes, and even high-frequency atrial tachyarrhythmia termination algorithms have all been proposed. In this article, we will try to synthesize the grounds for and findings of the different lines of research currently being developed

Modelling and simulation techniques to investigate pharmacokinetics, pharmacodynamics, and drug-drug interactions

Modelling and simulation (M&S) techniques can support characterisation and understanding of pharmacokinetics (PK), pharmacodynamics (PD), and drug-drug interactions (DDI) of drugs, therewith supporting dosing strategies during drug development and regulatory decision making. Three endothelin receptor antagonists were investigated by developing target-mediated drug disposition (TMDD) PKPD models, explaining the nonlinear PK behaviour, hypothesising a class effect and revealing an effect on PK through endogenous rhythms in receptor fluctuation. The DDI potential of fluvoxamine is a therapeutically unpleasant characteristic, but useful for its usage as a lead substance for DDI predictions with physiology-based (PB) PK modelling. Fluvoxamine was investigated using a population PK approach, enabling the characterisation and quantification of the influence of CYP2D6 phenotype and cigarette smoking its PK, thus supporting the role of fluvoxamine in a network for DDI.Modellierungs- und Simulationstechniken (M&S) können zur Charakterisierung und zum Verständnis des pharmakokinetischen (PK) und pharmakodynamischen (PD) Verhaltens eines Arzneimittels eingesetzt werden und damit Dosierungsstrategien und Entscheidungsfindung während der Arzneimittelentwicklung und für regulatorische Zwecke unterstützen. Endothelin-Rezeptor-Antagonisten (ERAs) sind eine Klasse von kleinen Molekülen, die endogenes Endothelin- 1 (ET-1) von seinen Rezeptor-Bindungsstellen verdrängen. Da ET-1 in der Pathogenese verschiedener Erkrankungen eine Rolle spielt, sind ERAs interessante Verbindungen für die Behandlung von Erkrankungen, in denen das ET-1-System involviert ist. Bosentan war der erste ERA, der für die Behandlung der pulmonalen arteriellen Hypertonie (PAH), einer tödlichen und seltenen Krankheit, zugelassen wurde. Da Bosentan eine ausgeprägte nichtlineare PK und Variabilität in der PK und PD aufweist, wurde ein Populationsmodell entwickelt, um die Eigenschaften des Medikaments besser zu charakterisieren und zu verstehen. Ein sogenanntes target-mediated drug disposition (TMDD) PKPD-Modell beschrieb die nichtlineare PK von Bosentan am besten. So gelang es, die starke Rezeptor-Bindungsaffinität von Bosentan abzubilden und gleichzeitig die Verdrängung des natürlichen ET-1 aus diesen Bindungsstellen, sowie die Wirkung auf Blutdruck und Herzfrequenz zu beschreiben. Die für Bosentan entwickelte Modellstruktur, das TMDD-Modell, wurde erfolgreich auf dessen Nachfolgeprodukte Clazosentan und Tezosentan angewandt. Das Modell ermöglichte die Unterscheidung zwischen selektiven ETA- und nicht-selektiven ETA- / ETB-Rezeptorantagonisten, was sich in der fehlenden Internalisierung des Wirkstoff-Rezeptor-Komplexes für Clazosentan widerspiegelt. Darüber hinaus wurde eine zeitlich schwankende Rezeptorexpression in das Modell integriert, die das beobachtete Phänomen mehrfacher Spitzen in den Plasmakonzentrationen der PK Profile beschreiben kann. Zusätzliche wurde ein PK-Populationsmodell für Fluvoxamin entwickelt, um den Einfluß des CYP2D6- Phänotyps und des Rauchens auf die Clearance und die Fluvoxamin-Exposition zu untersuchen. Ein Ein- Kompartiment-Modell mit kombinierter linearer Absorption nullter und erster Ordnung sowie linearer Elimination wurde erfolgreich auf die Daten angewendet. Das Modell zeigte, dass bei schlechten CYP2C6 Metabolisierern höhere Fluvoxamin-Plasmakonzentrationen zu erwarten sind, da die Metabolisierung von Fluvoxamin durch CYP2D6 reduziert ist. Gleichzeitig wurde gezeigt, dass das Rauchen von Zigaretten den CYP1A2-Stoffwechsel von Fluvoxamin induziert und zusätzlich zu einer Abnahme der oralen Absorption führt. Folglich wird erwartet, dass die Exposition bei Rauchern im Vergleich zu Nichtrauchern abnimmt. Das Modell unterstrich und bestätigte die Ergebnisse eines physiologiebasierten PK (PBPK) Modells von Fluvoxamin als Teil eines Netzwerks für Arzneimittelwechselwirkungen mit Theophyllin, Koffein, Rifampicin und Midazolam, welches nun für Vorhersagen von Arzneimittelwechselwirkungen mit CYP1A2 verwendet werden kann

Physiologically-Based Pharmacokinetic Modeling to Support the Clinical Management of Drug-Drug Interactions With Bictegravir

Bictegravir is equally metabolized by cytochrome P450 (CYP)3A and uridine diphosphate-glucuronosyltransferase (UGT)1A1. Drug-drug interaction (DDI) studies were only conducted for strong inhibitors and inducers, leading to some uncertainty whether moderate perpetrators or multiple drug associations can be safely coadministered with bictegravir. We used physiologically-based pharmacokinetic (PBPK) modeling to simulate DDI magnitudes of various scenarios to guide the clinical DDI management of bictegravir. Clinically observed DDI data for bictegravir coadministered with voriconazole, darunavir/cobicistat, atazanavir/cobicistat, and rifampicin were predicted within the 95% confidence interval of the PBPK model simulations. The area under the curve (AUC) ratio of the DDI divided by the control scenario was always predicted within 1.25-fold of the clinically observed data, demonstrating the predictive capability of the used modeling approach. After the successful verification, various DDI scenarios with drug pairs and multiple concomitant drugs were simulated to analyze their effect on bictegravir exposure. Generally, our simulation results suggest that bictegravir should not be coadministered with strong CYP3A and UGT1A1 inhibitors and inducers (e.g., atazanavir, nilotinib, and rifampicin), but based on the present modeling results, bictegravir could be administered with moderate dual perpetrators (e.g., efavirenz). Importantly, the inducing effect of rifampicin on bictegravir was predicted to be reversed with the concomitant administration of a strong inhibitor such as ritonavir, resulting in a DDI magnitude within the efficacy and safety margin for bictegravir (0.5-2.4-fold). In conclusion, the PBPK modeling strategy can effectively be used to guide the clinical management of DDIs for novel drugs with limited clinical experience, such as bictegravir

Momentum

Momentum was an exhibition of work by 8 applied artists who incorporate digital technologies in the creation of their artworks. The exhibition included 7 original objects created by Illner, using a combination of traditional craft-based and digital technologies such as rapid prototyping and laser engraving, and in materials such as paper, glass and silver. The show took place at Craft in the Bay, which is a leading centre for showcasing new crafts in Wales, with an internationally recognised reputation. The show travelled to the University of Hertfordshire (UH Galleries), a national centre for the theory of practice-led research (2012/13). An accompanying symposium brought together the artists the issues and themes arising from the use of new technologies within contemporary crafts. Illner's pieces were also shown in Framework Gallery (UH) as part of a group show The Printed Image (2012). Illner's work for this show was "an enquiry and exploration with materials, processes and techniques." (Dr. Cathy Treadaway, Momentum catalogue) Illner is described as a maker with “a playful and creative approach to materials and forms – these contrasting qualities are fundamental to her way of thinking, making and inspiring others.” (Felicity Cooke, Momentum catalogue). This work continues Illner's ongoing research project exploring how the digital can be embedded within materials, to create new possibilities in form and technique. Includes collaboration with other craftspeople and technical specialists, in order to develop innovative technical solutions to material connections. Illner’s current research use laser engraving on layered glass to create virtual imagery through shadow and reflection, challenging viewers to reflect on their perception of materials and their visual characteristics. Illner's practice-led research has also been shown in UK and European galleries over the last 20 years. Her work features in the Crafts Council and other private collections

A biregional survey and review of first-line treatment failure and second-line paediatric antiretroviral access and use in Asia and southern Africa

To better understand the need for paediatric second-line antiretroviral therapy (ART), an ART management survey and a cross-sectional analysis of second-line ART use were conducted in the TREAT Asia Paediatric HIV Observational Database and the IeDEA Southern Africa (International Epidemiologic Databases to Evaluate AIDS) regional cohorts