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Hintergrund: Die kardiale Magnetresonanztomographie (CMR) gilt als Referenzstandard für die Beurteilung der linksventrikulären Funktion und des Volumens des linken Ventrikels (LV). Neuartige Echtzeittechniken versprechen eine schnelle Bildgebung bei freier Atmung mit ähnlicher Qualität. Ziel dieser Studie war es, die Genauigkeit der standardmäßigen Steady-State-Free-Precession (SSFP)-Cine-Bildgebung bei angehaltenem Atem mit der gleichen Sequenz unter Verwendung von drei Signalmittelungen, während freier Atmung sowie mit einer Compressed-Sensing (Cs)- Echtzeittechnik während der freien Atmung zur Beurteilung von LV-Volumen und Masse zu vergleichen.
Methoden: 24 Probanden wurden mit einer Standard-SSFP-Technik bei angehaltenem Atem (BH), mit derselben Technik bei freier Atmung unter Verwendung von drei durchschnittlichen Herzzyklen (SA-FB) sowie mit einem CS-Echtzeitprotokoll bei freier Atmung (CS-FB) untersucht. Verglichen wurden die Erfassungsdauer, die Genauigkeit sowie die Inter- und Intraobserver-Variabilität von LV-Funktion, Volumen und Masse.
Ergebnisse: Die Echtzeit-Bildgebung war erheblich schneller als die freie Atmung mit drei Signalmittelwerten (p<0.001). Die Korrelation zwischen dem Referenzstandard (BH) und den beiden anderen Techniken war ausgezeichnet mit einem r2 für SA-FB vs. BH zwischen 0.74 - 0.89 und einem r2 für CS-FB vs. BH zwischen 0.81 und 0.94. SA-FB ergab mittlere Fehler zwischen 5.9% und 15% für verschiedene LV-Parameter, während CS-FB zu mittleren Fehlern von 6.5%bis 13% führte. Die Inter- und Intraobserver-Variabilität war bei der Echtzeit-Bildgebung ausgezeichnet und bei der SSFP-Bildgebung (SA-FB und BH) gut.
Schlussfolgerung: Sowohl ein Standardprotokoll mit 3 Signalmittelungen, während der freien Atmung als auch die Compressed Sensing liefern genaue und reproduzierbare Messungen des LV, während die Echtzeit-Bildgebung wesentlich schneller ist.
Adaptive threshold estimation procedures sample close to a subject’s perceptual threshold by dynamically adapting the stimulation based on the subject’s performance. Yet, perceptual thresholds not only depend on the observers’ sensory capabilities but also on any bias in terms of their expectations and response preferences, thus distorting the precision of the threshold estimates. Using the framework of signal detection theory (SDT), independent estimates of both, an observer’s sensitivity and internal processing bias can be delineated from threshold estimates. While this approach is commonly available for estimation procedures engaging the method of constant stimuli (MCS), correction procedures for adaptive methods (AM) are only scarcely applied. In this article, we introduce a new AM that takes individual biases into account, and that allows for a bias-corrected assessment of subjects’ sensitivity. This novel AM is validated with simulations and compared to a typical MCS-procedure, for which the implementation of bias correction has been previously demonstrated.
Comparing AM and MCS demonstrates the viability of the presented AM. Besides its feasibility, the results of the simulation reveal both, advantages, and limitations of the proposed AM. The procedure has considerable practical implications, in particular for the design of shaping procedures in sensory training experiments, in which task difficulty has to be constantly adapted to an observer’s performance, to improve training efficiency.
Targeted delivery of nucleic acids is gaining momentum due to improved efficacy, selectivity, increased circulation time and enhanced tissue retention in target cells. Using nucleic acid-based therapies previously undruggable targets have proven now to be amenable for treatment. Currently, several methods for preparing targeted or labelled delivery vehicles for nucleic acids are based on liposomal formulations. Lipid nanoparticles (LNPs) are structurally different from liposomes and these methods should therefore be evaluated before being translated to siRNA LNPs preparation protocols. Here, we describe a robust and facile method for the preparation of targeted or fluorescently labelled siRNA LNPs. Using a copper free strain-promoted azide-alkyne cycloaddition (SPAAC) we demonstrate that post-insertion of ligand-lipid conjugates into preformed LNPs is superior to direct-surface modification because it preserves the physicochemical parameters of the LNPs. We found that the time point of solvent removal by dialysis is critical and affects the hydrodynamic diameter of the LNPs; post-insertion after dialysis shows the smallest increase in hydrodynamic diameter and polydispersity index (PDI). The post-insertion of ligand-lipid conjugates also proceeded with rapid kinetics and high efficacy over a wide temperature range. Using this optimised protocol, we generated siRNA LNPs containing both targeting and fluorescent tracking ligands allowing us to monitor siRNA LNP uptake kinetics in dependence of the targeting ligand. In aggregate, we describe a robust approach for the generation of targeted and labelled siRNA LNPs that allows their controlled and facile decoration with ligand combinations.
The relationship between achievement of a pathologic complete response (pCR) and favorable long-term outcome varies among breast cancer subtypes. We aimed to highlight which neoadjuvant treatment strategy could be most successful in each breast cancer subtype. A recent FDA meta-analysis on randomized neoadjuvant breast cancer trials suggests that the survival differences of patients with or without a pCR were less pronounced in luminal A-like tumors, despite the overall favorable prognosis of these patients. Moreover, even though the strong prognostic effect of pCR in HER2 positive and TNBC, the NOAH study was the only trial which showed a trend in surrogacy of pCR for long-term outcome in HER2-positive subtype. Results from GeparTrio study suggest that patients with hormone-positive tumors might need a response-guided approach, with either an intensification of treatment in case of an early response or a change to other chemotherapy in case of no early response. Furthermore, data from German neoadjuvant trials confirm that an increasing number of chemotherapy cycles is associated with a higher pCR rate, especially in patients with HER2-positive/hormone-positive tumors. In line with these suggestions, Tryphaena study showed a pCR rate that exceeding the 60% threshold, the highest pCR results presented in a large multicenter study. In TNBC, the highest pCR rate in the German neoadjuvant studies was obtained with the simultaneous application of docetaxel, doxorubicin and cyclophosphamide for 6 cycles. However, as shown in GaparQuinto and NSABP 40 trials, treatment effect in TNBC might be further maximized by adding bevacizumab, and two randomized neoadjuvant trials are expected this year to report data on the efficacy of carboplatin.
Nitric oxide causes ADP-ribosylation and inhibition of glyceraldehyde-3-phosphate dehydrogenase
(1992)
Nitric oxide and nitric oxide-generating agents like 3-morpholinosydnonimine (SIN-1) stimulate the mono-ADP-ribosylation of a cytosolic, 39-kDa protein in various tissues. This protein was purified from human platelet cytosol by conventional and fast protein liquid chromatography techniques. N-terminal sequence analysis identified the isolated protein as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Nitric oxide stimulates the auto-ADP-ribosylation of GAPDH in a time and concentration-dependent manner with maximal effects after about 60 min. Associated with ADP-ribosylation is a loss of enzymatic activity. NAD(+)-free enzyme is not inhibited by SIN-1, indicating the absolute requirement of NAD+ as the substrate of the ADP-ribosylation reaction. Inhibition of the glycolytic enzyme GAPDH may be relevant as a cytotoxic effect of NO complementary to its inhibitory actions on iron-sulfur enzymes like aconitase and electron transport proteins of the respiratory chain.
Hepatology highlights
(2013)
The case of a 64 year old female patient is presented who has treated herself for 9 months with various Indian Ayurvedic herbal products for her vitiligo and experienced a causally related severe hepatotoxicity (ALT, 601 U/L; AST, 663 U/L; Bilirubin, 5.0 mg/dL). After discontinuation, a rapid improvement was observed. Causality assessment with the updated CIOMS (Council for International Organizations of Medical Sciences) scale showed a probable causality (+8 points) for Bakuchi tablets containing extracts from Psoralea corylifolia leaves with psoralens as ingredients, as the primary candidate causing the hepatotoxic reaction. The degree of probability was lower with +6 points for other used herbs: Khadin tablets containing extracts from Acacia catechu leaves; Brahmi tablets containing Eclipta alba or Bacopa monnieri; and Usheer tea prepared from Vetivexia zizaniodis. The case is the first report of Indian Ayurvedic herbal products being potentially hepatotoxic in analogy to some other herbs.
This review critically analyzes the clinical data of patients with suspected kava hepatotoxicity and suggests recommendations for minimizing risk. Kava is a plant (Piper methysticum) of the pepper family Piperaceae, and its rhizome is used for traditional aqueous extracts in the South Pacific Islands and for commercial ethanolic and acetonic medicinal products as anxiolytic herbs in Western countries. A regulatory ban for ethanolic and acetonic kava extracts was issued in 2002 for Germany on the basis of reports connecting liver disease with the use of kava, but the regulatory causality assessment was a matter of international discussions. Based on one positive reexposure test with the kava drug, it was indeed confirmed that kava is potentially hepatotoxic. In subsequent studies using a structured, quantitative and hepatotoxicity specific causality assessment method in 14 patients with liver disease described worldwide, causality for kava ± co-medicated drugs and dietary supplements including herbal ones was highly probable (n = 1), probable (n = 4) or possible (n = 9) regarding aqueous extracts (n = 3), ethanolic extracts (n = 5), acetonic extracts (n = 4), and mixtures containing kava (n = 2). Risk factors included overdose, prolonged treatment, and comedication with synthetic drugs and dietary supplements comprizing herbal ones in most of the 14 patients. Hepatotoxicity occurred independently of the used solvent, suggesting poor kava raw material quality as additional causative factor. In conclusion, in a few individuals kava may be hepatotoxic due to overdose, prolonged treatment, comedication, and probably triggered by an unacceptable quality of the kava raw material; standardization is now required, minimizing thereby hepatotoxic risks.
Hepatotoxicity by drugs and dietary supplements (DDS) is a rare and unpredictable event but with the risk of a life-threatening clinical course when it occurs. It may emerge despite intensive chemical, toxicological and observational studies that indicate no hepatotoxic signals. This suggests major clinical and regulatory issues that must be addressed in the area of accurate testing, reporting, and accessibility of reliable data. Consequently, in a clinical setting, safety concerns are key elements in the treatment of patients, and require that the diagnosis of DDS hepatotoxicity clearly be established. Causality of DDS hepatotoxicity may be pursued using a diagnostic algorithm consisting of a pre-test, a main-test as the scale of the updated CIOMS (Council for International Organizations of Medical Sciences), and a post-test. The results of these tests are then sent item by item to the National Health Agency, where the case will undergo further evaluation for pharmacovigilance, strategic aspects and safety issues. After this analysis, all items of the tests are included in the regulatory database freely accessible to the health and scientific community. With this diagnostic and regulatory algorithm the risk of misdiagnoses and inappropriate regulatory measures may be minimized and the safety improved. In conclusion, DDS hepatotoxicity is a rare but is a potentially life-threatening entity requiring a reliable diagnosis with the aid of a diagnostic algorithm, and a thorough pharmacovigilance evaluation by national and international health agencies. Safety aspects in DDS hepatotoxicity represent a major clinical and regulatory issue and should consequently be addressed.
