Dispensing pico to nanolitre of a natural hydrogel by laser-assisted bioprinting

<p>Abstract</p> <p>Background</p> <p>Laser-assisted bioprinting of multi-cellular replicates in accordance with CAD blueprint may substantially improve our understandings of fundamental aspects of 3 D cell-cell and cell-matrix interactions <it>in vitro</it>. For predictable printing results, a profound knowledge about effects of different processing parameters is essential for realisation of 3 D cell models with well-defined cell densities.</p> <p>Methods</p> <p>Time-resolved imaging of the hydrogel jet dynamics and quantitative assessment of the dependence of printed droplet diameter on the process characteristics were conducted.</p> <p>Results</p> <p>The existence of a counterjet was visualised, proving the bubble collapsing theory for the jet formation. Furthermore, by adjusting the viscosity and height of the applied hydrogel layer in combination with different laser pulse energies, the printing of volumes in the range of 10 to 7000 picolitres was demonstrated. Additionally, the relationship between the viscosity and the layer thickness at different laser pulse energies on the printed droplet volume was identified.</p> <p>Conclusions</p> <p>These findings are essential for the advancement of laser-assisted bioprinting by enabling predictable printing results and the integration of computational methods in the generation of 3 D multi-cellular constructs.</p

Reference values and physiological characterization of a specific isolated pig kidney perfusion model

BACKGROUND: Models of isolated and perfused kidneys are used to study the effects of drugs, hazardous or toxic substances on renal functions. Since physiological and morphological parameters of small laboratory animal kidneys are difficult to compare to human renal parameters, porcine kidney perfusion models have been developed to simulate closer conditions to the human situation, but exact values of renal parameters for different collection and perfusion conditions have not been reported so far. If the organs could be used out of regular slaughtering processes animal experiments may be avoided. METHODS: To assess renal perfusion quality, we analyzed different perfusion settings in a standardized model of porcine kidney hemoperfusion with organs collected in the operating theatre (OP: groups A-D) or in a public abattoir (SLA: group E) and compared the data to in vivo measurements in living animals (CON). Experimental groups had defined preservation periods (0, 2 and 24 hrs), one with additional albumin in the perfusate (C) for edema reduction. RESULTS: Varying perfusion settings resulted in different functional values (mean ± SD): blood flow (RBF [ml/min*100 g]: (A) 339.9 ± 61.1; (C) 244.5 ± 53.5; (D) 92.8 ± 25.8; (E) 153.8 ± 41.5); glomerular fitration (GFR [ml/min*100 g]: (CON) 76.1 ± 6.2; (A) 59.2 ± 13.9; (C) 25.0 ± 10.6; (D) 1.6 ± 1.3; (E) 16.3 ± 8.2); fractional sodium reabsorption (RF(Na )[%] (CON) 99.8 ± 0.1; (A) 82.3 ± 8.1; (C) 86.8 ± 10.3; (D) 38.4 ± 24.5; (E) 88.7 ± 5.8). Additionally the tubular coupling-ratio of Na-reabsorption/O(2)-consumption was determined (T(Na)/O(2)-cons [mmol-Na/mmol- O(2)] (CON) 30.1; (A) 42.0, (C) 80.6; (D) 17.4; (E) 23.8), exhibiting OP and SLA organs with comparable results. CONCLUSION: In the present study functional values for isolated kidneys with different perfusion settings were determined to assess organ perfusion quality. It can be summarized that the hemoperfused porcine kidney can serve as a biological model with acceptable approximation to in vivo renal physiology, also if the organs originate from usual slaughtering processes

Improving Clinical ECG-based Atrial Fibrosis Quantification With Neural Networks Through in silico P waves From an Extensive Virtual Patient Cohort

Fibrotic atrial cardiomyopathy is characterized by a replacement of healthy atrial tissue with diffuse patches exhibiting slow electrical conduction properties and altered myocardial tissue structure, which provides a substrate for the maintenance of reentrant activity during atrial fibrillation (AF). Therefore, an early detection of atrial fibrosis could be a valuable risk marker for new-onset AF episodes to select asymptomatic subjects for screening, allowing for timely intervention and optimizing therapy planning. We examined the potential of estimating the fibrotic tissue volume fraction in the atria based on P waves of the 12-lead ECG recorded in sinus rhythm in a quantitative and noninvasive way. Our dataset comprised 68,282 P waves from healthy subjects and 42,227 P waves from AF patients with low voltage areas in the atria, as well as 642,400 simulated P waves of a virtual cohort derived from statistical shape models with different extents of the left atrial myocardium replaced by fibrosis. The root mean squared error for estimating the left atrial fibrotic volume fraction on a clinical test set with a neural network trained on features extracted from simulated and clinical P waves was 16.57 %. Our study shows that the 12-lead ECG contains valuable information on atrial tissue structure. As such it could potentially be employed as an inexpensive and widely available tool to support AF risk stratification in clinical practic

Personalized ablation vs. conventional ablation strategies to terminate atrial fibrillation and prevent recurrence

Aims The long-term success rate of ablation therapy is still sub-optimal in patients with persistent atrial fibrillation (AF), mostly due to arrhythmia recurrence originating from arrhythmogenic sites outside the pulmonary veins. Computational modelling provides a framework to integrate and augment clinical data, potentially enabling the patient-specific identification of AF mechanisms and of the optimal ablation sites. We developed a technology to tailor ablations in anatomical and functional digital atrial twins of patients with persistent AF aiming to identify the most successful ablation strategy. Methods and results Twenty-nine patient-specific computational models integrating clinical information from tomographic imaging and electro-anatomical activation time and voltage maps were generated. Areas sustaining AF were identified by a personalized induction protocol at multiple locations. State-of-the-art anatomical and substrate ablation strategies were compared with our proposed Personalized Ablation Lines (PersonAL) plan, which consists of iteratively targeting emergent high dominant frequency (HDF) regions, to identify the optimal ablation strategy. Localized ablations were connected to the closest non-conductive barrier to prevent recurrence of AF or atrial tachycardia. The first application of the HDF strategy had a success of >98% and isolated only 5–6% of the left atrial myocardium. In contrast, conventional ablation strategies targeting anatomical or structural substrate resulted in isolation of up to 20% of left atrial myocardium. After a second iteration of the HDF strategy, no further arrhythmia episode could be induced in any of the patient-specific models. Conclusion The novel PersonAL in silico technology allows to unveil all AF-perpetuating areas and personalize ablation by leveraging atrial digital twins

Biology of Plasmopara viticola - Approach to a biological control of grapevine downy mildew

Plasmopara viticola, the causai agent of grapevine downy mildew is very well adapted to its host pianI. Therefore it is very difficult to develop methods for the biological control which meet the requests of ecological viticulture. One of the possibilities for a biological control of grapevine downy mildew is the usage of the natural resistance potential of the European cultivars of Vitis vinifera, more exactly the induced resistance. Another way is the use of specific inhibitors which either stop the infection process or have an effect on the interaction of the pathogen with the host pianI. Whereas generai information about the resistance reactions in plants is available and the first results were also won for vine, the knowledge about inhibitors is very scanty. The basic prerequisite to develop methods and strategies for the biological control of grapevine downy mildew is a comprehensive knowledge about the biology of P. viticola, especially so with respect to the interaction between pathogen and host. Since P. viticola is well adapted to the host plant, the development of biological methods is a scientific and technical challenge. P. viticola is indigenous in the south-eastern part of North America with a damp warm climate where it can be found on different autochtonous Vitis species. Due to the coevolution of the pathogen and the host a balanced relationship exists between the pathogen's virulence and the host's resistance. In contrast the European Vitis vinifera cultivars are highly susceptible for P. viticola; they have got in contact with the pathogen only 120 years ago and no adaptation has been developed in this short period of time. According to our hypothesis, a lack of a fast recognition of the pathogen results in a delayed resistance response of V. vinifera cultivars. The growth and development of P. viticola is \.ery fast on the host plant and reproduction as well as propagation potential is high. In addition, the growing conditions of grapevine, e.g. regional coverage of viticulture, dense canopy and humid climate, promote epidemic

Разработка и проектирование устройств для мобилизации людей в аэропортах

Объектом исследования выступает организация обслуживания авиапассажиров в аэропортах. Цель работы: проектирование устройства для мобилизации людей в аэропортах и разработка программного обеспечения на базе ОС Android для использования авиапассажирами в качестве управления транспортным средством. В процессе исследования проводится анализ организации предполетного обслуживания авиапассажиров в аэропортах. Основные характеристики: работа состоит из введения, трёх глав, заключения, списка использованных источников и ряда приложений. В результате исследования было разработано и спроектировано инновационное устройство для мобилизации людей в аэропортах и мобильное приложение на базе операционной системы Android, позволяющее осуществлять управление транспортным средством в помещении.The object of the research is the organization of the service of air passengers at airports. Objective: to design a device for mobilizing people at airports and developing Android-based software for use by air passengers as a means of driving a vehicle. In the course of the study, an analysis of the organization of pre-flight service of air passengers at airports is carried out. Main characteristics: the work consists of an introduction, three chapters, conclusion, list of references and a number of applications. As a result of the study, an innovative device for mobilizing people at airports and a mobile application based on the Android operating system were developed and designed to control the vehicle indoors

Data Resource Profile : Panel Study Labour Market and Social Security (PASS)

Nicht vorhanden Not availabl

Two-Step-Model of Photosensitivity in Cerium-doped Fibers

The photosensitivity of various cerium-doped fibers has been experimentally investigated for both excimer- and femtosecond-laser illumination. The results of single-pulse, few-pulse and multi-pulse inscription of fiber-Bragg-gratings with both laser systems and the thermal aging of those gratings demonstrated the restrictions of the conventional color center model for cerium-doped fibers. To explain the short-term stability of single-pulse gratings against long-term stability of multi-pulse gratings, an extension into a two-step-model was deduced