Übergangsmetallvermittelte [2+2+2]-Zyklotrimerisierungsreaktionen zum Aufbau anellierter Phthalide : Intermediate zur Synthese von Anguzyklinonen

Anguzykline sind eine große Gruppe von Naturstoffen. Ihnen ist gemein, dass sie eine Benz[a]anthracen-Struktur besitzen oder dass sie in der Biosynthese aus einer Verbindung mit einem solchem Grundgerüst hervorgegangen sind. Viele Vertreter der Anguzykline sind bioaktive Substanzen mit insbesondere antibiotischer Wirkung. In dieser Arbeit wurde eine flexible, modulare Synthese für Anguzykline erarbeitet. Eine Schlüsselreaktion stellte die intramolekulare [2+2+2]-Zykloaddition aus Triinen zu Phthaliden dar. Die in dieser Umwandlung eingesetzten Triine enthalten eine Diin- und eine Monoinkomponente, die über eine Esterbindung miteinander verknüpft sind. Die intramolekulare [2+2+2]-Zyklotrimerisierung wurde an zwei verschiedenen Strukturen der Triinsysteme untersucht: Zum einen Triine, in denen Nona-2,8-diinsäuren mit 1-Aryl-propargylalkoholen verknüpft waren und zum anderen Substrate, in denen die Propargylsäureester von 1-Aryl-nona-2,8-diin-1-olen gebildet wurden. Für die Umsetzung wurden zwei verschiedene Katalysatoren verwendet. Neben dem Wilkinsonkatalysator wurde der Rutheniumkatalysator [Cp*RuCl(cod)] eingesetzt. Beide Katalysatoren sind für die Reaktion geeignet und ergänzen sich hinsichtlich der verschiedenen Triinsysteme. Die Phthalide dienten als Intermediate für den Aufbau eines Tetrahydrobenz[a]anthrachinon-Grundgerüst. Zum Aufbau dieser Struktur wurde eine Synthesesequenz zur Gerüstumlagerung vorgestellt und die Synthesemethode auf verschiedene Vertreter der Anguzyklin-Familie angewendet. Besonderes Augenmerk wurde auf die Synthese des Urdamycinon B gelegt, in dem das Grundgerüst C-glykosidisch mit einem Olivosesubstituenten verknüpft ist.

Structural characterization of intermediate and metastable phases by electron microscopy

Structure characterization of nanocrystalline intermediates and metastable phases is of primary importance for a deep understanding of synthetic processes undergoing solid-to-solid state phase transitions. Understanding the evolution from the first nucleation stage to the final synthetic product supports not only the optimization of existing processes, but might assist in tailoring new synthetic paths. A systematic investigation of intermediates and metastable phases is hampered because it is impossible to produce large crystals and only in few cases a pure synthetic product can be obtained. Structure investigation by X-ray powder diffraction methods is still challenging on nanoscale, especially when the sample is polyphasic. Electron diffraction has the advantage to collect data from single nanoscopic crystals, but is limited by data incompleteness, dynamical effects and fast deterioration of the sample under the electron beam. Automated diffraction tomography (ADT), a recently developed technique, making possible to collect more complete three-dimensional electron diffraction data and to reduce at the same time dynamical scattering and beam damage, thus allowing to investigate even beam sensitive materials (f.e. hydrated phases and organics). At present, ADT is the only technique able to deliver complete three-dimensional structural information from single nanoscopic grains, independently from other surrounding phases. Thus, ADT is an ideal technique for the study of on-going processes where different phases exist at the same time and undergo several structural transitions. In this study ADT was used as the main technique for structural characterization for three different systems and combined subsequently with other techniques, among which high-resolution transmission electron microscopy (HRTEM), cryo-TEM imaging, X-ray powder diffraction (XRPD) and energy disperse X-ray spectroscopy (EDX).rnAs possible laser host materials, i.e. materials with a broad band emission in the near-infrared region, two unknown phases were investigated in the ternary oxide system M2O-Al2O3-WO3 (M = K, Na). Both phases exhibit low purity as well as non-homogeneous size distribution and particle morphology. The structures solved by ADT are also affected by pseudo-symmetry. rnSodium titanate nanotubes and nanowires are both intermediate products in the synthesis of TiO2 nanorods which are used as additives to colloidal TiO2 film for improving efficiency of dye-sensitized solar cells (DSSC). The structural transition from nantubes to nanowires was investigated in a step by step time-resolved study. Nanowires were discovered to consist of a hitherto unknown phase of sodium titanate. This new phase, typically affected by pervasive defects like mutual layer shift, was structurally determined ab-initio on the basis of ADT data. rnThe third system is related with calcium carbonate nucleation and early crystallization. The first part of this study is dedicated to the extensive investigations of calcium carbonate formation in a step by step analysis, up to the appearance of crystalline individua. The second part is dedicated to the structure determination by ADT of the first-to-form anhydrated phase of CaCO3: vaterite. An exhaustive structure analysis of vaterite had previously been hampered by diffuse scattering, extra periodicities and fast deterioration of the material under electron irradiation. rn

Mining tissue microarray data to uncover combinations of biomarker expression patterns that improve intermediate staging and grading of clear cell renal cell cancer

PURPOSE: Tumor stage and nuclear grade are the most important prognostic parameters of clear cell renal cell carcinoma (ccRCC). The progression risk of ccRCC remains difficult to predict particularly for tumors with organ-confined stage and intermediate differentiation grade. Elucidating molecular pathways deregulated in ccRCC may point to novel prognostic parameters that facilitate planning of therapeutic approaches. EXPERIMENTAL DESIGN: Using tissue microarrays, expression patterns of 15 different proteins were evaluated in over 800 ccRCC patients to analyze pathways reported to be physiologically controlled by the tumor suppressors von Hippel-Lindau protein and phosphatase and tensin homologue (PTEN). Tumor staging and grading were improved by performing variable selection using Cox regression and a recursive bootstrap elimination scheme. RESULTS: Patients with pT2 and pT3 tumors that were p27 and CAIX positive had a better outcome than those with all remaining marker combinations. A prolonged survival among patients with intermediate grade (grade 2) correlated with both nuclear p27 and cytoplasmic PTEN expression, as well as with inactive, nonphosphorylated ribosomal protein S6. By applying graphical log-linear modeling for over 700 ccRCC for which the molecular parameters were available, only a weak conditional dependence existed between the expression of p27, PTEN, CAIX, and p-S6, suggesting that the dysregulation of several independent pathways are crucial for tumor progression. CONCLUSIONS: The use of recursive bootstrap elimination, as well as graphical log-linear modeling for comprehensive tissue microarray (TMA) data analysis allows the unraveling of complex molecular contexts and may improve predictive evaluations for patients with advanced renal cancer.

Urethral toxicity vs. cancer control-Lessons to be learned from high-dose rate brachytherapy combined with intensity-modulated radiation therapy in intermediate- and high-risk prostate cancer

To describe biochemical relapse-free survival (BRFS) and late toxicity after combined high-dose rate brachytherapy (HDR-B) and intensity-modulated radiation therapy (IMRT) in intermediate- and high-risk prostate cancer patients.

Plectin interacts with the rod domain of type III intermediate filament proteins desmin and vimentin

Plectin is a versatile cytolinker protein critically involved in the organization of the cytoskeletal filamentous system. The muscle-specific intermediate filament (IF) protein desmin, which progressively replaces vimentin during differentiation of myoblasts, is one of the important binding partners of plectin in mature muscle. Defects of either plectin or desmin cause muscular dystrophies. By cell transfection studies, yeast two-hybrid, overlay and pull-down assays for binding analysis, we have characterized the functionally important sequences for the interaction of plectin with desmin and vimentin. The association of plectin with both desmin and vimentin predominantly depended on its fifth plakin repeat domain and downstream linker region. Conversely, the interaction of desmin and vimentin with plectin required sequences contained within the segments 1A-2A of their central coiled-coil rod domain. This study furthers our knowledge of the interaction between plectin and IF proteins important for maintenance of cytoarchitecture in skeletal muscle. Moreover, binding of plectin to the conserved rod domain of IF proteins could well explain its broad interaction with most types of IFs.

Echinococcus multilocularis and its intermediate host: a model of parasite-host interplay

Host-parasite interactions in the E. multilocularis-intermediate host model depend on a subtle balance between cellular immunity, which is responsible for host's resistance towards the metacestode, the larval stage of the parasite, and tolerance induction and maintenance. The pathological features of alveolar echinococcosis. the disease caused by E. multilocularis, are related both to parasitic growth and to host's immune response, leading to fibrosis and necrosis, The disease spectrum is clearly dependent on the genetic background of the host as well as on acquired disturbances of Th1-related immunity. The laminated layer of the metacestode, and especially its carbohydrate components, plays a major role in tolerance induction. Th2-type and anti-inflammatory cytokines, IL-10 and TGF-beta, as well as nitric oxide, are involved in the maintenance of tolerance and partial inhibition of cytotoxic mechanisms. Results of studies in the experimental mouse model and in patients suggest that immune modulation with cytokines, such as interferon-alpha, or with specific antigens could be used in the future to treat patients with alveolar echinococcosis and/or to prevent this very severe parasitic disease.

Costs of transcatheter versus surgical aortic valve replacement in intermediate-risk patients

Transcatheter aortic valve replacement (TAVR) offers a new treatment option for patients with aortic stenosis, but costs may play a decisive role in decision making. Current studies are evaluating TAVR in an intermediate-risk population. We assessed the in-hospital and 1-year follow-up costs of patients undergoing TAVR and surgical aortic valve replacement (SAVR) at intermediate operative risk and identified important cost components.

Using stress testing to guide primary prevention of coronary heart disease among intermediate-risk patients: a cost-effectiveness analysis

Noninvasive stress testing might guide the use of aspirin and statins for primary prevention of coronary heart disease, but it is unclear if such a strategy would be cost effective.

Clinical outcomes of patients with estimated low or intermediate surgical risk undergoing transcatheter aortic valve implantation

AimsTranscatheter aortic valve implantation (TAVI) is an established treatment alternative to surgical aortic valve replacement in high-risk and inoperable patients and outcomes among patients with estimated low or intermediate risk remain to be determined. The aim of this study was to assess clinical outcomes among patients with estimated low or intermediate surgical risk undergoing TAVI.Methods and resultsBetween August 2007 and October 2011, 389 consecutive patients underwent TAVI and were categorized according to the Society of Thoracic Surgeons (STS) score into low (STS < 3%; n = 41, 10.5%), intermediate (STS ≥3% and ≤8%, n = 254, 65.3%), and high-risk (STS > 8%; n = 94, 24.2%) groups for the purpose of this study. Significant differences were found between the groups (low risk vs. intermediate risk vs. high risk) for age (78.2 ± 6.7 vs. 82.7 ± 5.7 vs. 83.7 ± 4.9, P < 0.001), body mass index (28.1 ± 6.1 vs. 26.5 ± 4.9 vs. 24.4 ± 4.6, P < 0.001), chronic renal failure (34 vs. 67 vs. 90%, P < 0.001), all-cause mortality at 30 days (2.4 vs. 3.9 vs. 14.9%, P = 0.001), and all-cause mortality at 1 year (10.1 vs. 16.1 vs. 34.5%, P = 0.0003). No differences were observed with regards to cerebrovascular accidents and myocardial infarction during 1-year follow-up.ConclusionIn contemporary practice, TAVI is not limited to inoperable or STS-defined high-risk patients and should be guided by the decision of an interdisciplinary Heart Team. Compared with patients at calculated high risk, well-selected patients with STS-defined intermediate or low risk appear to have favourable clinical outcomes.

Heterogeneity of patients with intermediate (BCLC B) Hepatocellular Carcinoma: proposal for a subclassification to facilitate treatment decisions

The intermediate stage of hepatocellular carcinoma (HCC) comprises a highly heterogeneous patient population and therefore poses unique challenges for therapeutic management, different from the early and advanced stages. Patients classified as having intermediate HCC by the Barcelona Clinic Liver Cancer (BCLC) staging system present with varying tumor burden and liver function. Transarterial chemoembolization (TACE) is currently recommended as the standard of care in this setting, but there is considerable variation in the clinical benefit patients derive from this treatment.In April 2012, a panel of experts convened to discuss unresolved issues surrounding the application of current guidelines when managing patients with intermediate HCC. The meeting explored the applicability of a subclassification system for intermediate HCC patients to tailor therapeutic interventions based on the evidence available to date and expert opinion. The present report summarizes the proposal of the expert panel: four substages of intermediate HCC patients, B1 to B4.

Changes in PESI scores predict mortality in intermediate-risk patients with acute pulmonary embolism

Although the Pulmonary Embolism Severity Index (PESI) accurately identifies 35% of patients with acute pulmonary embolism (PE) as being low risk, some patients deemed high risk by the PESI on admission might be treated safely in the outpatient environment. This retrospective cohort study included a total of 304 consecutive patients with acute PE, classified at the time of hospital admission into PESI class III. The PESI was recalculated 48 h after admission (PESI(48)) and each patient reclassified into the corresponding risk category. The primary outcome of the study was all-cause mortality between day 2 and day 30 after PE diagnosis. 26 (8.5%) patients (95% CI 5.4-11.7%) died between day 2 and day 30 after PE diagnosis. Investigators reclassified 83 (27.3%) patients (95% CI 22.3-32.3%) as low risk (classes I and II) at 48 h. 30-day mortality in these patients was 1.2% (95% CI 0-3.5%) as opposed to 11.3% (95% CI 7.1-15.5%) in those who remained high risk. The net improvement in reclassification was estimated at 54% (p<0.001). In a cohort of intermediate-risk patients with acute PE, calculation of the PESI(48) allows identification of those patients at very low risk of dying during the first month of follow-up.

A 3-center comparison of 1-year mortality outcomes between transcatheter aortic valve implantation and surgical aortic valve replacement on the basis of propensity score matching among intermediate-risk surgical patients

This study sought to compare all-cause mortality in patients at intermediate surgical risk undergoing transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement (SAVR).