Aims: Ventricular tachyarrhythmias (VTs) are common in the pathologically remodelled heart. These arrhythmias can be lethal, necessitating acute treatment like electrical cardioversion to restore... Show moreAims: Ventricular tachyarrhythmias (VTs) are common in the pathologically remodelled heart. These arrhythmias can be lethal, necessitating acute treatment like electrical cardioversion to restore normal rhythm. Recently, it has been proposed that cardioversion may also be realized via optically controlled generation of bioelectricity by the arrhythmic heart itself through optogenetics and therefore without the need of traumatizing high-voltage shocks. However, crucial mechanistic and translational aspects of this strategy have remained largely unaddressed. Therefore, we investigated optogenetic termination of VTs (i) in the pathologically remodelled heart using an (ii) implantable multi-LED device for (iii) in vivo closed-chest, local illumination. Methods and results: In order to mimic a clinically relevant sequence of events, transverse aortic constriction (TAC) was applied to adult male Wistar rats before optogenetic modification. This modification took place 3 weeks later by intravenous delivery of adeno-associated virus vectors encoding red-activatable channelrhodopsin or Citrine for control experiments. At 8-10 weeks after TAC, VTs were induced ex vivo and in vivo, followed by programmed local illumination of the ventricular apex by a custom-made implanted multi-LED device. This resulted in effective and repetitive VT termination in the remodelled adult rat heart after optogenetic modification, leading to sustained restoration of sinus rhythm in the intact animal. Mechanistically, studies on the single cell and tissue level revealed collectively that, despite the cardiac remodelling, there were no significant differences in bioelectricity generation and subsequent transmembrane voltage responses between diseased and control animals, thereby providing insight into the observed robustness of optogenetic VT termination. Conclusion: Our results show that implant-based optical cardioversion of VTs is feasible in the pathologically remodelled heart in vivo after local optogenetic targeting because of preserved optical control over bioelectricity generation. These findings add novel mechanistic and translational insight into optical ventricular cardioversion. Show less
Copper nanoparticles (CuNPs) are used extensively in a wide range of products and the potential for toxicological impacts in the aquatic environment is of high concern. In this study, the fate and... Show moreCopper nanoparticles (CuNPs) are used extensively in a wide range of products and the potential for toxicological impacts in the aquatic environment is of high concern. In this study, the fate and the acute toxicity of spherical 50 nm copper nanoparticles was assessed in juvenile rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas) and zebrafish (Danio rerio) for in vivo aqueous exposures following standardized OECD 203 guideline tests. The fate of the CuNPs in the aqueous media was temperature dependent. At the higher study temperature (26 ± 1 C), there was both an enhanced particle aggregation and higher rate of dissolution compared with that at the lower study temperature (15 ± 1 C). 96 h LC50s of the CuNPs were 0.68 ± 0.15, 0.28 ± 0.04 and 0.22 ± 0.08 mg Cu/L for rainbow trout, fathead minnow and zebrafish, respectively. The 96 h lowest-observed-effect concentration (LOEC) for the CuNPs were 0.17, 0.023 and <0.023 mg/L for rainbow trout, fathead minnow, and zebrafish respectively, and are below the predicted environmental concentration of CuNPs for some aquatic environments suggesting a possible ecotoxicological risk to fish. Soluble copper was one of main drivers for the acute toxicity of the copper nanoparticles suspensions. Both CuNPs suspension and copper nitrate caused damage to gill filaments and gill pavement cells, with differences in sensitivity for these effects between the fish species studied. We show therefore common toxicological effects of CuNPs in different fish species but with differences in sensitivity with implications for hazard extrapolation between fish species. Show less
There is epidemiological evidence that the use of some insulin analogues by diabetic patients is correlated with an increased cancer risk. In vitro exposure experiments revealed that insulin... Show moreThere is epidemiological evidence that the use of some insulin analogues by diabetic patients is correlated with an increased cancer risk. In vitro exposure experiments revealed that insulin glargine (LANTUS) was the only commercial insulin analogue with an increased mitogenic potential. In the human body the injected insulin glargine is rapidly degraded into two main metabolites with a metabolic activity. These two compounds have a mitogenic potential that was not increased compared to regular insulin. Gene expression analysis on a stimulated MCF7-based cell line panel showed that the insulin-like growth factor 1 (IGF1) receptor was the main receptor involved in the insulin analogue induced mitogenic signaling. A chronic exposure experiment with the humanized p53R270H+/-WAPCre mouse model revealed that none of the commercially available insulin analogues induced mammary gland tumor multiplicity or decreased the tumor latency time. However, a follow-up whole transcriptome analysis indicated that some tumors in the insulin glargine treatment group had a higher Warburg potential. Altogether, these results suggest that insulin glargine exposure was not involved in tumor initiation but it might have affected tumor progression. Show less
The project focuses on visualizing Agrobacterium Mediated Transformation (AMT) of host cells by real time microscopy. With new visualization techniques the function of several proteins, which have... Show moreThe project focuses on visualizing Agrobacterium Mediated Transformation (AMT) of host cells by real time microscopy. With new visualization techniques the function of several proteins, which have recently been discovered in our lab to play a role during AMT, are studied. Show less
In this thesis, several strategies are presented that aim to facilitate the analysis and visualization of whole-body in vivo data of small animals. Based on the particular challenges for image... Show moreIn this thesis, several strategies are presented that aim to facilitate the analysis and visualization of whole-body in vivo data of small animals. Based on the particular challenges for image processing, when dealing with whole-body follow-up data, we addressed several aspects in this thesis. The developed methods are tailored to handle data of subjects with significantly varying posture and address the large tissue heterogeneity of entire animals. In addition, we aim to compensate for lacking tissue contrast by relying on approximation of organs based on an animal atlas. Beyond that, we provide a solution to automate the combination of multimodality, multidimensional data. Show less
