Applying logic to pulmonary artery catheter use

Mansour and colleagues recommend not routinely using the pulmonary artery catheter to guide hemodynamic management in the intensive care unit, because the perceived benefits are largely intangible [1]. Pulmonary artery catheter monitoring of the right ventricular ejection fraction (RVef) and of the right ventricular end-diastolic volume (EDV), however, reflects powerful yet underutilized relationships that assess right ventricular performance. Since the cardiac output equals the product of the RVef, the EDV and the heart rate, one can assess the RVef to EDV relations as direct measures of right ventricular performance. A series of RVef, EDV and heart rate combinations can give the same cardiac output (Figure 1); monitoring or targeting cardiac output alone ignores this reality. For example, in hypovolemia the EDV is low and the RVef is increased

DNA-kodierte Substanzbibliotheken: Chemische Stabilisierung der DNA, Entwicklung neuer Synthesemethoden und Identifizierung von TEAD-YAP-Inhibitoren

Die Technologie der DNA-kodierten Substanzbibliotheken (DELs) hat sich in den letzten Jahren als eine vielversprechende Alternative zum Hochdurchsatz-Screening zur Identifizierung kleiner organischer Moleküle, welche mit pharmazeutisch relevanten, biologischen Zielstrukturen interagieren, etabliert. DELs bestehen aus einer Vielzahl an DNA-kodierten Molekülen, welche gleichzeitig in Affinitäts-basierten Selektionsassays gegenüber einer Zielstruktur getestet und im Anschluss anhand ihrer einzigartigen DNA-Sequenz leicht „entschlüsselt“ werden können. Ein Großteil der in der Literatur beschriebenen DELs wird über „split and pool“-Synthesen in wässriger Lösung synthetisiert. Dies hat zur Folge, dass viele gängige Synthesemethoden der organischen Chemie, die auf trockene Lösungsmittel angewiesen sind, nicht für die DEL-Synthese zur Anwendung kommen können. Eine weitere Limitierung zur Herstellung von DELs stellt die Stabilität der DNA gegenüber verschiedenen Reaktionsbedingungen dar. Viele als Katalysatoren standardmäßig in der präparativen organischen Chemie eingesetzte Metallsalze sowie stark saure Reaktionsbedingungen können in der DEL-Synthese nicht verwendet werden. Im Rahmen dieser Arbeit wurde der Fokus auf die Synthese von DELs basierend auf einer Festphasenstrategie gelegt. Diese bietet neben der freien Wahl des Lösungsmittels den Vorteil, dass die Nukleobasen der DNA vollständig geschützt vorliegen und somit die gesamte DNA eine höhere Stabilität aufweist. Im ersten Teil der Arbeit wird die Synthese einer Indol-fokussierten DNA-kodierten Substanzbibliothek, ausgehend von dem chemisch sehr stabilen, controlled pore glass (CPG)-gebundenen Hexathymidin („hexT“)-Adapteroligonukleotid beschrieben (thymidine-initiated DNA-encoded chemistry, TIDEC). Die im Vergleich zu anderen DELs recht kleine Bibliothek von 8.112 Molekülen konnte im Selektionsscreening vielversprechende Wirkstoffkandidaten für schwierig zu adressierende Proteine wie dem Transkriptionsfaktor TEAD4 liefern. Das in diesem Verfahren verwendete Adapteroligonukleotid hexT erlaubt jedoch keine Kodierung von Startmaterialien. Diese Einschränkung wird im weiteren Verlauf der Arbeit adressiert durch die Überführung weiterer organischer Synthesemethoden (Ugi-Vierkomponentenreaktion, Ugi-Azid-Vierkomponentenreaktion, Ugi-Vierkomponenten-aza-Wittig-Reaktion, Groebke-Blackburn-Bienaymé-Dreikomponentenreaktion, AgOAc-vermittelte 1,3-dipolare Azomethin-Ylid-Cycloaddition, Yb(PFO)3-vermittelte Dreikomponenten-Pyrazolsynthese) auf ein neues, effizienteres DNA-Kodierungsformat, das den Einsatz von kodierten Startmaterialien ermöglicht. Damit auch harschere Reaktionsbedingungen in der DEL-Synthese verwendet werden können, wird im letzten Teil der Arbeit durch den Austausch der vulnerablen Purinnukleobase Adenin durch die chemisch modifizierte Base 7-Deazaadenin die Etablierung eines chemisch stabilisierten DNA-Barcodes beschrieben

Isocyanide Multicomponent Reactions on Solid-Phase-Coupled DNA Oligonucleotides for Encoded Library Synthesis

Isocyanide multicomponent reactions play a prominent role in drug discovery. This chemistry has hardly been investigated for compatibility with DNA-encoded combinatorial synthesis. The Ugi, Ugi-azide, and Groebke-Blackburn-Bienaymé reactions are well-tolerated by DNA on the solid phase and show a broad scope. However, an oxadiazole-forming variant of the Ugi reaction caused DNA depurination, requiring a more stable hexathymidine DNA for encoded library synthesis. Cheminformatic analysis revealed that isocyanide multicomponent-reaction-based encoded libraries cover a diverse chemical space

Scanning protein surfaces with DNA-encoded libraries

Understanding the ligandability of a target protein, defined as the capability of a protein to bind drug-like compounds on any site, can give important stimuli to drug-development projects. For instance, inhibition of protein–protein interactions usually depends on the identification of protein surface binders. DNA-encoded chemical libraries (DELs) allow scanning of protein surfaces with large chemical space. Encoded library selection screens uncovered several protein–protein interaction inhibitors and compounds binding to the surface of G protein-coupled receptors (GPCRs) and kinases. The protein surface-binding chemotypes from DELs are predominantly chemically modified and cyclized peptides, and functional small-molecule peptidomimetics. Peptoid libraries and structural peptidomimetics have been less studied in the DEL field, hinting at hitherto less populated chemical space and suggesting alternative library designs. Roughly a third of bioactive molecules evolved from smaller, target-focused libraries. They showcase the potential of encoded libraries to identify more potent molecules from weak, for example, fragment-like, starting points

Chemically stabilized DNA barcodes for DNA-encoded chemistry

DNA-encoded compound libraries are a widely used small molecule screening technology. One important aim in library design is the coverage of chemical space through structurally diverse molecules. Yet, the chemical reactivity of native DNA barcodes limits the toolbox of reactions for library design. Substituting the chemically vulnerable purines by 7-deazaadenine, which exhibits tautomerization stability similar to natural adenine with respect to the formation of stable Watson–Crick pairs, yielded ligation-competent, amplifiable, and readable DNA barcodes for encoded chemistry with enhanced stability against protic acid- and metal ion-promoted depurination. The barcode stability allowed for straightforward translation of 16 exemplary reactions that included isocyanide multicomponent reactions, acid-promoted Pictet–Spengler and Biginelli reactions, and metal-promoted pyrazole syntheses on controlled pore glass-coupled barcodes for diverse DEL design. The Boc protective group of reaction products offered a convenient handle for encoded compound purification

Longitudinal measures of lung function in infants with bronchopulmonary dysplasia

We previously demonstrated that infants with a history of bronchopulmonary dysplasia (BPD) exhibit airflow obstruction and air trapping. The purpose of this study was to assess longitudinal changes in pulmonary function in infants with a history of BPD over the first 3 years of life, and the relationship to somatic growth. Spirometry was measured using the raised volume rapid thoracoabdominal compression technique, and lung volumes measured by plethysmography. Eighteen infants (mean gestational age ± SD 27.3 ± 2.2 weeks, birthweight 971 ± 259 g) underwent two lung function studies. Average age at first test was 58.8 weeks. Spirometry demonstrated significant reductions in forced expiratory volume in 0.5 sec (FEV 0.5 , 76.0 ± 15.9% predicted, Z-score −2.13 ± 1.69), forced expiratory flow at 75% of expired forced vital capacity (FEF 75 , 54.8 ± 31.1%, −3.58 ± 2.73), and FEF 25–75 (67.8 ± 33.3%, −1.79 ± 1.76). Group mean total lung capacity (TLC) was in the low normal range (82.9 ± 13.5% predicted) and residual volume (RV)/TLC was mildly elevated (122.4 ± 38.2% predicted). Repeat testing was performed an average of 32.7 weeks after initial testing. At re-evaluation, group mean lung volumes and flows tracked at or near their previous values; thus, in general, there was a lack of catch-up growth. However, compared to infants with below average or average somatic growth (as represented by g/day), infants with above average growth showed significantly greater improvements in percent predicted FVC, FEV 0.5 , TLC, and RV/TLC (all P  < 0.05, ANOVA). We conclude that longitudinal measures of pulmonary function in infants and young children with BPD demonstrate significant airflow obstruction and modest restriction, which tends to persist with time. On the other hand, infants with above average somatic growth showed greater lung growth than their peers. Additional studies examining the effects of various nutritional regimens on lung function are warranted. Pediatr Pulmonol. 2011; 46:369–375. © 2010 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83461/1/21378_ftp.pd

TEAD-YAP Interaction Inhibitors and MDM2 Binders from DNA-Encoded Indole-Focused Ugi Peptidomimetics

DNA-encoded combinatorial synthesis provides efficient and dense coverage of chemical space around privileged molecular structures. The indole side chain of tryptophan plays a prominent role in key, or “hot spot”, regions of protein–protein interactions. A DNA-encoded combinatorial peptoid library was designed based on the Ugi four-component reaction by employing tryptophan-mimetic indole side chains to probe the surface of target proteins. Several peptoids were synthesized on a chemically stable hexathymidine adapter oligonucleotide “hexT”, encoded by DNA sequences, and substituted by azide-alkyne cycloaddition to yield a library of 8112 molecules. Selection experiments for the tumor-relevant proteins MDM2 and TEAD4 yielded MDM2 binders and a novel class of TEAD-YAP interaction inhibitors that perturbed the expression of a gene under the control of these Hippo pathway effectors

Sildenafil attenuates pulmonary inflammation and fibrin deposition, mortality and right ventricular hypertrophy in neonatal hyperoxic lung injury

<p>Abstract</p> <p>Background</p> <p>Phosphodiesterase-5 inhibition with sildenafil has been used to treat severe pulmonary hypertension and bronchopulmonary dysplasia (BPD), a chronic lung disease in very preterm infants who were mechanically ventilated for respiratory distress syndrome.</p> <p>Methods</p> <p>Sildenafil treatment was investigated in 2 models of experimental BPD: a lethal neonatal model, in which rat pups were continuously exposed to hyperoxia and treated daily with sildenafil (50–150 mg/kg body weight/day; injected subcutaneously) and a neonatal lung injury-recovery model in which rat pups were exposed to hyperoxia for 9 days, followed by 9 days of recovery in room air and started sildenafil treatment on day 6 of hyperoxia exposure. Parameters investigated include survival, histopathology, fibrin deposition, alveolar vascular leakage, right ventricular hypertrophy, and differential mRNA expression in lung and heart tissue.</p> <p>Results</p> <p>Prophylactic treatment with an optimal dose of sildenafil (2 × 50 mg/kg/day) significantly increased lung cGMP levels, prolonged median survival, reduced fibrin deposition, total protein content in bronchoalveolar lavage fluid, inflammation and septum thickness. Treatment with sildenafil partially corrected the differential mRNA expression of amphiregulin, plasminogen activator inhibitor-1, fibroblast growth factor receptor-4 and vascular endothelial growth factor receptor-2 in the lung and of brain and c-type natriuretic peptides and the natriuretic peptide receptors NPR-A, -B, and -C in the right ventricle. In the lethal and injury-recovery model we demonstrated improved alveolarization and angiogenesis by attenuating mean linear intercept and arteriolar wall thickness and increasing pulmonary blood vessel density, and right ventricular hypertrophy (RVH).</p> <p>Conclusion</p> <p>Sildenafil treatment, started simultaneously with exposure to hyperoxia after birth, prolongs survival, increases pulmonary cGMP levels, reduces the pulmonary inflammatory response, fibrin deposition and RVH, and stimulates alveolarization. Initiation of sildenafil treatment after hyperoxic lung injury and continued during room air recovery improves alveolarization and restores pulmonary angiogenesis and RVH in experimental BPD.</p