How to Deal with Weak Interactions in Noncovalent Complexes Analyzed by Electrospray Mass Spectrometry: Cyclopeptidic Inhibitors of the Nuclear Receptor Coactivator 1-STAT6

Mass spectrometry, and especially electrospray ionization, is now an efficient tool to study noncovalent interactions between proteins and inhibitors. It is used here to study the interaction of some weak inhibitors with the NCoA-1/STAT6 protein with KD values in the μM range. High signal intensities corresponding to some nonspecific electrostatic interactions between NCoA-1 and the oppositely charged inhibitors were observed by nanoelectrospray mass spectrometry, due to the use of high ligand concentrations. Diverse strategies have already been developed to deal with nonspecific interactions, such as controlled dissociation in the gas phase, mathematical modeling, or the use of a reference protein to monitor the appearance of nonspecific complexes. We demonstrate here that this last methodology, validated only in the case of neutral sugar–protein interactions, i.e., where dipole–dipole interactions are crucial, is not relevant in the case of strong electrostatic interactions. Thus, we developed a novel strategy based on half-maximal inhibitory concentration (IC50) measurements in a competitive assay with readout by nanoelectrospray mass spectrometry. IC50 values determined by MS were finally converted into dissociation constants that showed very good agreement with values determined in the liquid phase using a fluorescence polarization assay

Management des malignen Melanoms und des Merkelzell-Karzinoms im Kopf-Hals-Bereich - Einfluss der Wächterlymphknotenbiopsie

Hintergrund: Sowohl das maligne Melanom (MM) als auch das Merkelzell-Karzinom (MZK) stellen hochaggressive Hauttumoren dar, die u.a. durch frühzeitige Metastasierung charakterisiert sind. Die primäre Therapie ist chirurgisch und beim MM durch eine S3-Leitlinie geregelt. Dennoch ist der Nutzen und die Praktikabilität der Wächterlymphknoten-Biopsie (WLKB) im Vergleich zur primären elektiven Neck dissection (ND) im Kopf-Hals-Bereich (KHB) nicht abschließend geklärt.Methodik: Es wurden zwischen 2006 und 2016 die Daten von 86 Patienten (76 MM, 10 MZK) retrospektiv ausgewertet. 57 WLKB wurden durchgeführt. Bei einer Detektionsrate von 89,5% und einer Falsch-Negativ-Rate (d.h. ein lokoregionäres Rezidiv innerhalb eines Jahres nach neg. WLKB) von 25% ergaben sich 39/57 neg. und 12/57 pos. Biopsien. Die Sensitivität betrug 75%, der Negativ-Prädiktive-Wert 89,5%. 11/12 der pos. WLK-Patienten erhielten zweizeitig eine ND mit weiteren Metastasen in 27,3% der Fälle. 16 Patienten erhielten eine elektive ND mit Metastasennachweis in 6 Fällen (37,5%). In 1/6 (16,7%) der Fälle, in denen die WLKB kein Ergebnis erbrachte, trat ein lokoregionäres Rezidiv auf. Die rezidivfreie 3-Jahres-Überlebensrate lag bei WLK-neg. Patienten bei 74,2% und bei WLK-pos. Patienten bei 22,9% (p=0,274).Schlussfolgerung: Die WLKB bleibt trotz einiger Vorteile (wenig invasives Staging, prognostischer Marker für das rezidivfreie Überleben) weiterhin mit einigen Fallstricken behaftet. Aufgrund des interdisziplinären Vorgehens und der Risiken falsch negativer WLKB, gegeben durch den Lymphabfluss und die komplexe Anatomie im KHB, sollte die Anwendung Tumorzentren vorbehalten bleiben. Insbesondere im KHB bedarf es aufgrund fehlender Langzeitdaten und unzureichender Fallzahlen weiteren multizentrischen Studien.Der Erstautor gibt keinen Interessenkonflikt an

A novel 3D-printed laryngoscope with integrated working channels for laryngeal surgery

BackgroundFor the surgical treatment of early-stage laryngeal cancer, the use of transoral laser microsurgery (TLM) has emerged as the gold standard. However, this procedure requires a straight line of sight to the operating field. Therefore, the patient's neck needs to be brought into a hyperextended position. In a considerable number of patients, this is not possible due to anomalies in the cervical spine anatomy or soft tissue scarring, e.g., after radiation. In these cases, adequate visualization of relevant laryngeal structures cannot be ensured using a conventional rigid operating laryngoscope, which may negatively affect the outcome of these patients.MethodsWe present a system based on a 3D-printed prototype of a curved laryngoscope with three integrated working channels (sMAC). The curved profile of the sMAC-laryngoscope is specifically adapted to the nonlinear anatomy of the upper airway structures. The central working channel provides access for flexible video endoscope imaging of the operating field while the two remaining channels provide access for flexible instrumentation. In a user study (n = 11), visualization and reachability of relevant laryngeal landmarks as well as the feasibility of basic surgical procedures with the proposed system were examined in a patient simulator. In a second setup, the system was evaluated for its applicability in a human body donor.ResultsAll participants of the user study were able to visualize, reach and manipulate the relevant laryngeal landmarks. Reaching those took significantly less time in the second attempt compared to the first one (27.5 s ± 5.2 s vs. 39.7 s ± 16.5 s, p = 0.008) indicating a significant learning curve for handling the system. Instrument changes were performed quickly and reliably by all participants (10.9 s ± 1.7 s). All participants were able to bring the bimanual instruments into position for a vocal fold incision. Relevant laryngeal landmarks could be visualized and reached in the human body donor setup.ConclusionPossibly, the proposed system may develop into an alternative treatment option for patients with early-stage laryngeal cancer and restricted mobility of the cervical spine in the future. Further improvements of the system could include finer end effectors and a flexible instrument with a laser cutting tool