Detektion photokatalytischer Aktivität aus der Einzelmolekülfluoreszenz organischer Farbstoffe

Der photokatalytische Prozess des konsekutiven photoinduzierten Elektronentransfers (konPET) beschreibt die schrittweise Akkumulation der Energie zweier sichtbarer Photonen für die Zwecke der organischen Synthese. Dieser Aktivierungsansatz, der an das Z-Schema der Photosynthese angelehnt ist, folgt damit der Idee einer künstlichen Photosynthese. Als konkretes Anwendungsbeispiel liegt dieser Arbeit ein photokatalytischer Zyklus zugrunde, in dem die verschiedenen angeregten Zustände des organischen Farbstoffs Rhodamin 6G (Rh6G) als reagierende Zustände agieren. Hier werden die einzelnen involvierten Reaktionsschritte dieses Zyklus auf der Ebene einzelner reagierender Moleküle schrittweise mechanistisch nachvollzogen und quantifiziert. Mit dem experimentellen Ansatz der Fluoreszenzkorrelationsspektroskopie (FCS) wird zunächst der Einfluss verschiedener Reaktionsparameter auf die Ausgangs- und Zielzustände des ersten stattfindenden photoinduzierten Elektronentransfer Schrittes (PET) parametrisiert. Schließlich wird die Reaktionsdynamik des geschlossenen Zyklus anhand einzelner, durch DNA-Doppelstränge immobilisierte Moleküle quantifiziert. Damit verkörpern die hier gezeigten Experimente eine Modellreaktion, in der eine chemische Transformation auf der Ebene einzelner reagierender Moleküle und Photonen beobachtet wird

Hepatobiliary MRI: Signal intensity based assessment of liver function correlated to 13C-Methacetin breath test

Gadoxetic acid (Gd-EOB-DTPA) is a paramagnetic MRI contrast agent with raising popularity and has been used for evaluation of imaging-based liver function in recent years. In order to verify whether liver function as determined by real-time breath analysis using the intravenous administration of C-13-methacetin can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI using signal intensity (SI) values. 110 patients underwent Gd-EOB-DTPA-enhanced 3-T MRI and, for the evaluation of liver function, a C-13-methacetin breath test (C-13-MBT). SI values from before (SIpre) and 20 min after (SIpost) contrast media injection were acquired by T1-weighted volume-interpolated breath-hold examination (VIBE) sequences with fat suppression. The relative enhancement (RE) between the plain and contrast-enhanced SI values was calculated and evaluated in a correlation analysis of C-13-MBT values to SIpost and RE to obtain a SI-based estimation of C-13-MBT values. The simple regression model showed a log-linear correlation of C-13-MBT values with SIpost and RE (p < 0.001). Stratified by 3 different categories of C-13-MBT readouts, there was a constant significant decrease in both SIpost (p <= 0.002) and RE (p <= 0.033) with increasing liver disease progression as assessed by the C-13-MBT. Liver function as determined using real-time C-13-methacetin breath analysis can be estimated quantitatively from GdEOB- DTPA-enhanced MRI using SI-based indices

Binding, Release and Functionalization of Intact Pnictogen Tetrahedra Coordinated to Dicopper Complexes

The bridging MeCN ligand in the dicopper(I) complexes [(DPFN)Cu2(μ,η1 : η1-MeCN)][X]2 (X=weakly coordinating anion, NTf2 (1 a), FAl[OC6F10(C6F5)]3 (1 b), Al[OC(CF3)3]4 (1 c)) was replaced by white phosphorus (P4) or yellow arsenic (As4) to yield [(DPFN)Cu2(μ,η2 : η2-E4)][X]2 (E=P (2 a–c), As (3 a–c)). The molecular structures in the solid state reveal novel coordination modes for E4 tetrahedra bonded to coinage metal ions. Experimental data and quantum chemical computations provide information concerning perturbations to the bonding in coordinated E4 tetrahedra. Reactions with N-heterocyclic carbenes (NHCs) led to replacement of the E4 tetrahedra with release of P4 or As4 and formation of [(DPFN)Cu2(μ,η1 : η1-MeNHC)][X]2 (4 a,b) or to an opening of one E−E bond leading to an unusual E4 butterfly structural motif in [(DPFN)Cu2(μ,η1 : η1-E4DippNHC)][X]2 (E=P (5 a,b), E=As (6)). With a cyclic alkyl amino carbene (EtCAAC), cleavage of two As−As bonds was observed to give two isomers of [(DPFN)Cu2(μ,η2 : η2-As4EtCAAC)][X]2 (7 a,b) with an unusual As4-triangle+1 unit

Long-term survival after percutaneous irreversible electroporation of inoperable colorectal liver metastases

Background: For colorectal liver metastases (CRLM) that are not amenable to surgery or thermal ablation, irreversible electroporation (IRE) is a novel local treatment modality and additional option. Methods: This study is a retrospective long-term follow-up of patients with CRLM who underwent IRE as salvage treatment. Results: Of the 24 included patients, 18(75.0%) were male, and the median age was 57 (range: 28-75) years. The mean time elapsed from diagnosis to IRE was 37.9 +/- 37.3 months. Mean overall survival was 26.5 months after IRE (range: 2.5-69.2 months) and 58.1 months after diagnosis (range: 14.8-180.1 months). One-, three-, and five-year survival rates after initial diagnosis were 100.0%, 79.2%, and 41.2%; after IRE, the respective survival rates were 79.1%, 25.0%, and 8.3%. There were no statistically significant differences detected in survival after IRE with respect to gender, age, T- or N-stage at the time of diagnosis, size of metastases subject to IRE, number of hepatic lesions, or time elapsed between IRE and diagnosis. Conclusion: For nonresectable CRLM, long-term survival data emphasize the value of IRE as a new minimally invasive local therapeutic approach in multimodal palliative treatment, which is currently limited to systemic or regional therapies in this setting

Different Ultrasound Shear Wave Elastography Techniques as Novel Imaging-Based Approaches for Quantitative Evaluation of Hepatic Steatosis—Preliminary Findings

Background: Modern ultrasound (US) shear-wave dispersion (SWD) and attenuation imaging (ATI) can be used to quantify changes in the viscosity and signal attenuation of the liver parenchyma, which are altered in hepatic steatosis. We aimed to evaluate modern shear-wave elastography (SWE), SWD and ATI for the assessment of hepatic steatosis. Methods: We retrospectively analyzed the US data of 15 patients who underwent liver USs and MRIs for the evaluation of parenchymal disease/liver lesions. The USs were performed using a multifrequency convex probe (1–8 MHz). The quantitative US measurements for the SWE (m/s/kPa), the SWD (kPa-m/s/kHz) and the ATI (dB/cm/MHz) were acquired after the mean value of five regions of interest (ROIs) was calculated. The liver MRI (3T) quantification of hepatic steatosis was performed by acquiring proton density fat fraction (PDFF) mapping sequences and placing five ROIs in artifact-free areas of the PDFF scan, measuring the fat-signal fraction. We correlated the SWE, SWD and ATI measurements to the PDFF results. Results: Three patients showed mild steatosis, one showed moderate steatosis and eleven showed no steatosis in the PDFF sequences. The calculated SWE cut-off (2.5 m/s, 20.4 kPa) value identified 3/4 of patients correctly (AUC = 0.73, p > 0.05). The SWD cut-off of 18.5 m/s/kHz, which had a significant correlation (r = 0.55, p = 0.034) with the PDFF results (AUC = 0.73), identified four patients correctly (p < 0.001). The ideal ATI (AUC = 0.53 (p < 0.05)) cut-off was 0.59 dB/cm/MHz, which showed a significantly good correlation with the PDFF results (p = 0.024). Conclusion: Hepatic steatosis can be accurately detected using all the US-elastography techniques applied in this study, although the SWD and the SWE showed to be more sensitive than the PDFF

Transarterial chemoembolization (TACE) with degradable starch microspheres (DSM) in hepatocellular carcinoma (HCC): multi-center results on safety and efficacy

Background: Hepatocellular carcinoma (HCC) is the 3rd leading cause of cancer-related death worldwide. The majority of HCCs are diagnosed in a stage that is not eligible for curative resection. For intermediate stage HCC, transarterial chemoembolization (TACE) is the recommended treatment. We evaluated the safety and efficacy of DSM (degradable starch microspheres) as embolic agent in transarterial chemoembolization (TACE) for the treatment of intermediate stage, non-resectable hepatocellular carcinoma (HCC). Methods and Findings: A national, multi-center observational study on the safety and efficacy of DSM-TACE for the treatment of intermediate HCC was conducted. The recruitment period for the study was from January 2010 to June 2014. The primary endpoints were safety and treatment response according to the mRECIST criteria. A total of 179 DSM-TACE procedures in 50 patients were included in the analysis. The therapeutic efficacy assessed with mRECIST was as follows: complete response (n=1; 2 %), 21 partial response (42 %), 13 stable disease (26 %), 9 progressive disease (18 %), and 6 incomplete data (12 %). Thus, the objective response rate was 44% (n=22) and disease control rate was 70% (n=35). A total of 76 immediate adverse events (AE) and 2 severe adverse events (SAE) were recorded. Forty-eight percent of patients (n=24) did not encounter any immediate AE/SAE. Between treatments, a total of 66 AE and one SAE were recorded. Twenty-four patients (48 %) did not encounter any AE/SAE in between treatments. Conclusion: The use of DSM as a TACE embolic agent appears to be safe for the treatment of HCC and has promising efficacy

Gd-EOB-DTPA-enhanced MRI for evaluation of liver function: Comparison betewwn signal-intensity-based indices and T1 relaxometry

Gadolinium ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) is a paramagnetic hepatobiliary magnetic resonance (MR) contrast agent. Due to its OATP1B1/B3-dependent hepatocyte-specific uptake and paramagnetic properties increasing evidence has emerged to suggest that Gd-EOBDTPA- enhanced MRI can be potentially used for evaluation of liver function. In this paper we compare the diagnostic performance of Gd-EOB-DTPA-enhanced relaxometry-based and commonly used signal-intensity (SI)-based indices, including the hepatocellular uptake index (HUI) and SI-based indices corrected by spleen or muscle, for evaluation of liver function, determined using the Indocyanin green clearance (ICG) test. Simple linear regression model showed a significant correlation of the plasma disappearance rate of ICG (ICG-PDR) with all Gd-EOB-DTPA-enhanced MRI-based liver function indices with a significantly better correlation of relaxometry-based indices on ICG-PDR compared to SI-based indices. Among SI-based indices, HUI achieved best correlation on ICG-PDR and no significant difference of respective correlations on ICG-PDR could be shown. Assessment of liver volume and consecutive evaluation of multiple linear regression model revealed a stronger correlation of ICG-PDR with both (SI)-based and T1 relaxometry-based indices. Thus, liver function can be estimated quantitatively from Gd-EOB-DTPA-enhanced MRI-based indices. Here, indices derived from T1 relaxometry are superior to SI-based indices, and all indices benefit from taking into account respective liver volumes

Development and evaluation of an image-free computer-assisted impingement detection technique for total hip arthroplasty

Periprosthetic or bony impingement in total hip arthroplasty (THA) has been correlated to dislocation, increased wear, reduced postoperative functionality with pain and/or decreased range of motion (ROM). We sought to study the accuracy and assess the reliability of measuring bony and periprosthetic impingement on a virtual bone model prior to the implantation of the acetabular cup with the help of image-free navigation technology in an experimental cadaver study. Impingement-free ROM measurements were recorded during minimally invasive, computer-assisted THA on 14 hips of 7 cadaveric donors. Preoperatively and postoperatively the donors were scanned using computed tomography (CT). Impingement-free ROM on three-dimensional CT-based models was then compared with corresponding, intraoperative navigation models. Bony/periprosthetic impingement can be detected with a mean accuracy limit of below 5° for motion angles, which should be reached after THA for activities of daily living with the help of image-free navigation technology