The frozen elephant trunk technique in acute aortic dissection: the ultimate solution? An institutional experience.

Objective: Acute aortic dissection remains a serious emergency in the field of cardiovascular medicine and a challenge for cardiothoracic surgeons. In the present study, we seek to compare the outcomes of different surgical techniques in the repair of type A acute aortic dissection. Methods: Between April 2015 and May 2023, 213 patients (82 women, aged: 63.9 ± 13.3 years) with acute aortic dissection (205 type A and 8 non-A-non-B dissections) underwent surgical treatment in our department. A total of 45 patients were treated with the frozen elephant trunk (FET) technique supported by the Thoraflex™ Hybrid prosthesis, 33 received total aortic arch replacement (TAR)-standard or conventional elephant trunk-treatment, and 135 were treated with hemiarch replacement (HR). Aortic arch surgery was performed in most patients under moderate hypothermic (28°C on average) circulatory arrest, with selective antegrade cerebral perfusion through the right axillary artery. Results: The rates of early mortality were 17.8% (38 perioperative deaths) in the whole population, 8.9% in the FET group of patients, and 33% and 17% in the TAR and HR group of patients, respectively (P-value 0.025). The rate of spinal cord injury was 2.3% (five patients), and a paresis of recurrent laryngeal occurred in 3.7% of patients (seven patients, four were treated with FET). Permanent neurological dysfunction occurred in 27 patients (12.7%). After a mean follow-up of 3 years, the rate of mid-term mortality of discharged patients was 19.4% (34 deaths: 7 FET, 4 TAR, and 23 HR) and the overall mortality rate was 33.8% [72 deaths: 11 FET (24.4%); 15 TAR (45.4%); 46 HR (34.1%)]. A total of 8 patients (17.8%) in whom FET was applied received additional endovascular treatment in the descending aorta. Conclusions: In our institutional experience, we found that the frozen elephant trunk technique with a high-end Thoraflex Hybrid prosthesis proved its surgical suitability in the treatment of acute aortic dissection with favorable outcomes. The FET technique and our perioperative management led to comparable neurological outcomes and reduced mortality rates in these emergency cases.

[Present-day policy of surgical treatment for type A acute aortic dissection]. / Sovremennaia taktika khirurgicheskogo lecheniia ostrogo rassloeniia aorty tipa A.

A surgical intervention for type A acute aortic dissection is the only effective method of treatment making it possible to prevent the development of life-threatening complications and to attain clinical recovery of the patient. Supracoronary replacement of the ascending aorta and the proximal portion of the aortic arch is considered to be the classical and most commonly used method of an open operative intervention. On the one hand, it is technically the simplest and shortest operation, and on the other, this surgical technique is often accompanied by long-term proximal and distal complications, and first of all those caused by a persistent false lumen. The accumulated surgical experience and contemporary operative techniques, as well as advances of intensive therapy in treatment of type A acute aortic dissection make it possible to currently perform more extensive primary resections in order to improve the remote results. Total aortic arch replacement, including the use of the 'frozen elephant trunk' technique leads to fast thrombosis of the false lumen, preventing progression of the disease of the thoracic aorta and promoting its positive remodelling. The article describes the perioperative therapeutic policy accepted and pursued in our medical facility, also presenting the authors' opinion on the role and place of the 'frozen elephant trunk' technique in rendering medical care for patients with type A acute aortic dissection.

Different shades of pancreatic ductal adenocarcinoma, different paths towards precision therapeutic applications.

BACKGROUND: Different histological and molecular subtypes of pancreatic ductal adenocarcinoma (PDAC), with different molecular composition and survival statistics, have recently been recognised. MATERIALS AND METHODS: This review describes the currently available studies regarding molecular and histological subtypes in PDAC. Studies from major cohorts such as International Cancer Genome Consortium as well as smaller cohorts are reviewed. We discuss where the described subtypes overlap, where the discrepancies are and which paths forward could be taken regarding diagnosis, ontogeny and therapy. RESULTS: Four molecular subtypes with strong overlap among the different studies can be found, next to a list of mixed findings. Two of the four subtypes (epithelial classical and mesenchymal basal-like) were represented in every study and were often discriminated in other solid tumours as well. These two subtypes differ substantially in prognosis. One biomarker has been discovered, only discriminating these two subtypes, and insights into subtype-specific therapeutic vulnerabilities are scarce. CONCLUSION: Subtypes can be reproducibly detected in cohorts of PDAC patients and two of them directly relate with prognosis. A consensus on the subtypes is warranted. Further discovery and validation studies are needed to identify strong biomarkers, to comprehend subtype ontogeny and to define strategies for precision medicine.

Student participation in the design of learning and teaching: Disentangling the terminology and approaches.

Background: Students are ever more involved in the design of educational practices, which is reflected in the growing body of literature about approaches to student participation. Similarities and differences between these approaches often remain vague since the terms are used interchangeably. This confusing and fragmented body of literature hampers our understanding the process and outcomes of student participation and choosing the most suitable approach for it. Method: We identified the three most frequently used terms related to the design of learning and teaching - design-based research (DBR), participatory design (PD), and co-creation - and disentangled the terminology by focusing on relevant definitions, aims, involvement of students, outcomes, and related terminology. Results: Differences between the approaches to student participation can be found in the degree to which students are the central actors and the degree to which the design is informed by educational theory. Conclusion: It is important to align the level of student participation with the purpose of the approach.

Lateral parietal cortex in the generation of behavior: Implications for apathy.

A reduction in goal-directed behavior, or apathy, occurs in neurological and psychiatric disorders, though its neural substrates remain unclear. Deficits in circuits connecting the prefrontal cortex to subcortical regions are considered to underlie apathy. Although apathy is empirically associated with widespread changes in these regions, studies across disorders also link apathy with the lateral parietal cortex. Such variety in regional involvement is consistent with the established role of prefrontal and subcortical regions in models of goal-directed behavior, and with the suggestion of subtypes of apathy. However, these models do not provide a basis for the involvement of the lateral parietal cortex with apathy. Here, we review the association between lateral parietal cortex dysfunction and apathy across disorders and analyze the putative cognitive functions that may link this region with goal-directed behavior. We suggest that neural processes in the angular and supramarginal gyri of the inferior parietal lobule may provide an interface enabling the transformation of internal goals to external actions through intentional initiation of action interrelated with mechanisms of primary sensorimotor transformation. Consequently, we propose that impairment in this process of embedding intended action in a 'body schema' facilitating adequate recruitment of an effector system, is the likely mechanism underlying the association between the lateral parietal cortex and apathy. Considering the evidence, we propose a revised neurocognitive model of apathy where deficient internal initiation of behavior mediated by the inferior parietal lobule may be sufficient, though not necessary, to reduce goal-directed behavior, and may constitute a volitional subtype of apathy.

Longitudinal analysis of the audiological phenotype in osteogenesis imperfecta: a follow-up study.

OBJECTIVE: This prospective study involved a longitudinal analysis of the progression of hearing thresholds in patients with osteogenesis imperfecta. METHODS: Audiometric results from 36 osteogenesis imperfecta patients (age range, 6-79 years) were compared between two test times with an average interval of 4 years. Audiometric evaluation included acoustic admittance measurements, acoustic stapedial reflex measurements, pure tone audiometry and otoacoustic emissions testing. RESULTS: Air conduction pure tone average, corrected for sex and age, and bone conduction pure tone average increased significantly in the study population (p < 0.05 and p < 0.001, respectively). In 14.3 per cent of the evaluated ears, an alteration in type and/or severity of hearing loss was observed. CONCLUSION: After an average time interval of four years, significant changes in hearing status occurred in a population of osteogenesis imperfecta patients. These findings highlight the importance of regular audiological follow up in osteogenesis imperfecta patients, including audiometry, and measurements of acoustic admittance, acoustic stapedial reflexes and otoacoustic emissions.

Technical aspects of using the 'ThoraflexTM Hybrid' prosthesis in acute type A aortic dissection. / Tekhnicheskie aspekty primeneniia proteza «ThoraflexTM Hybrid¼ pri ostrom rassloenii aorty tipa A.

The most tried out, 'classical' technique of the operation in acute type A aortic dissection is supracoronary prosthetic repair of the ascending aorta and proximal portion of the aortic arch, as the simplest and fastest intervention. However, this technique is associated with late complications related primarily to formation of a persistent false lumen leading to formation of an aneurysm of the descending aorta. Total prosthetic repair of the aortic arch, including the 'frozen elephant trunk' technique, contributes to thrombosis of the false lumen and remodelling of the thoracic aorta. The article describes peculiarities of this technique illustrated by an example of implanting the 'ThoraflexTM Hybrid' prosthesis.

Application of open-path Fourier transform infrared spectroscopy for atmospheric monitoring of a CO2 back-production experiment at the Ketzin pilot site (Germany).

During a controlled "back-production experiment" in October 2014 at the Ketzin pilot site, formerly injected CO2 was retrieved from the storage formation and directly released to the atmosphere via a vent-off stack. Open-path Fourier transform infrared (OP FTIR) spectrometers, on-site meteorological parameter acquisition systems, and distributed CO2 point sensors monitored gas dispersion processes in the near-surface part of the atmospheric boundary layer. The test site provides a complex and challenging mosaic-like surface setting for atmospheric monitoring which can also be found at other storage sites. The main aims of the atmospheric monitoring of this experiment were (1) to quantify temporal and spatial variations in atmospheric CO2 concentrations around the emitting vent-off stack and (2) to test if and how atmospheric monitoring can cope with typical environmental and operational challenges. A low environmental risk was encountered during the whole CO2 back-production experiment. The study confirms that turbulent wind conditions favor atmospheric mixing processes and are responsible for rapid dilution of the released CO2 leading to decreased detectability at all sensors. In contrast, calm and extremely stable wind conditions (especially occurring during the night) caused an accumulation of gases in the near-ground atmospheric layer with the highest amplitudes in measured gas concentration. As an important benefit of OP FTIR spectroscopic measurements and their ability to detect multiple gas species simultaneously, emission sources could be identified to a much higher certainty. Moreover, even simulation models using simplified assumptions help to find suitable monitoring network designs and support data analysis for certain wind conditions in such a complex environment.

In Vitro Reconstitution of Atg8 Conjugation and Deconjugation.

Macroautophagy, hereafter autophagy, is a major degradation pathway in eukaryotic systems that allows the removal of large intracellular structures such as entire organelles or protein aggregates, thus contributing to the homeostasis of cells and tissues. Autophagy entails the de novo formation of an organelle termed autophagosome, where a cup-shaped structure called isolation membrane nucleates in proximity of a cytoplasmic cargo material. Upon elongation and closure of isolation membranes, the mature autophagosome delivers the sequestered cargo into the lysosomal system for degradation. Among the factors for autophagosome formation are the autophagy-related (Atg) proteins belonging to the Atg8 conjugation system. In this system, the ubiquitin-like Atg8 protein is conjugated to the membrane lipid phosphatidylethanolamine present in autophagosomal membranes. Atg8 can also be removed from membranes by Atg4-mediated deconjugation. Here, we describe in vitro systems that recapitulate the enzymatic reactions occurring in vivo by presenting expression and purification strategies for all the components of the Saccharomyces cerevisiae Atg8 conjugation system. We also present protocols for in vitro Atg8 conjugation and deconjugation reactions employing small and giant unilamellar vesicles.

Wave propagation in spatially modulated tubes.

We investigate wave propagation in rotationally symmetric tubes with a periodic spatial modulation of cross section. Using an asymptotic perturbation analysis, the governing quasi-two-dimensional reaction-diffusion equation can be reduced into a one-dimensional reaction-diffusion-advection equation. Assuming a weak perturbation by the advection term and using projection method, in a second step, an equation of motion for traveling waves within such tubes can be derived. Both methods predict properly the nonlinear dependence of the propagation velocity on the ratio of the modulation period of the geometry to the intrinsic width of the front, or pulse. As a main feature, we observe finite intervals of propagation failure of waves induced by the tube's modulation and derive an analytically tractable condition for their occurrence. For the highly diffusive limit, using the Fick-Jacobs approach, we show that wave velocities within modulated tubes are governed by an effective diffusion coefficient. Furthermore, we discuss the effects of a single bottleneck on the period of pulse trains. We observe period changes by integer fractions dependent on the bottleneck width and the period of the entering pulse train.

Ischemic Left Ventricular Perforation Covered by a Thrombus in a Patient Presenting with Cerebral Ischemia: Importance of Time-Sensitive Performance and Adequate Interpretation of Bedside Transthoracic Echography.

If myocardial infarction remains silent, only clinical signs of complications may unveil its presence. Life-threatening complications include myocardial rupture, thrombus formation, or arterial embolization. In the presented case, a 76-year-old patient was admitted with left-sided hemiparesis. In duplex sonography, a critical stenosis of the right internal carotid artery was identified and initially but retrospectively incorrectly judged as the potential cause for ischemia. During operative thromboendarterectomy, arterial embolism of the right leg occurred coincidentally, more likely pointing towards a cardioembolic origin. Percutaneous interventions remained unsuccessful and local fibrinolysis was applied. Delayed bedside echocardiography by an experienced cardiologist demonstrated a discontinuity of the normal myocardial texture of the left ventricular apex together with an echodense, partly floating structure merely attached by a thin bridge not completely sealing the myocardial defect, accompanied by pericardial effusion. The patient was immediately transferred to emergency cardiac surgery with extirpation of the thrombus, aortocoronary bypass graft placement, and aneurysmectomy. This didactic case reveals decisive structural shortcomings in patient's admission and triage processes and underlines, if performed timely and correctly, the value of transthoracic echocardiography as a noninvasive and cost-effective tool allowing immediate decision-making, which, in this case, led to the correct but almost fatally delayed diagnosis.

Shade affects responses to drought and flooding - acclimation to multiple stresses in bittersweet (Solanum dulcamara L.).

Plants exposed to environmental stress often respond by a change in their phenotypic traits. These changes in trait expression may alleviate the negative effect of such stress factors. However, if multiple stresses are present, responses are likely to be less predictable and hence do not necessarily correlate to plant performance. This study tested if this expectation was true, by subjecting Solanum dulcamara plants to various simultaneous stress factors. Plants were grown in well-watered conditions, drought or flooding, and exposed to either full light or shade for 4 weeks. Shoot and root biomass, stem morphological parameters, such as height, number of nodes and length of stem internodes, and leaf traits like length, specific leaf area, chlorophyll content and stomatal conductance were determined. Both variation in light and in water availability typically caused slower growth, and resulted in distinct phenotypic changes in stem, leaf and root traits. However, effects of stresses on the expression of traits were not always additive. Instead, some combined stress responses (e.g. leaf size) appeared to be limited by physical or physiological constraints, whereas other responses were opposite to each other (e.g. root:shoot ratio), resulting in an intermediate phenotype in the combined stress treatment. These data suggest that in natural conditions, where combined stress factors are likely to be present, the optimal phenotype may not necessarily be expressed. Responses of plants to multiple stress factors may therefore not be associated with immediate advantages in terms of increased performance.

Front propagation in channels with spatially modulated cross section.

Propagation of traveling fronts in a three-dimensional channel with spatially varying cross section is reduced to an equivalent one-dimensional reaction-diffusion-advection equation with boundary-induced advection term. Treating the advection term as a weak perturbation, an equation of motion for the front position is derived. We analyze channels whose cross sections vary periodically with L along the propagation direction of the front. Taking the Schlögl model as a representative example, we calculate analytically the nonlinear dependence of the front velocity on the ratio L/l where l denotes the intrinsic front width. In agreement with finite-element simulations of the three-dimensional reaction-diffusion dynamics, our theoretical results predicts boundary-induced propagation failure for a finite range of L/l values. In particular, the existence of the upper bound of L/l can be completely understood based on the linear eikonal equation. Last, we demonstrate that the front velocity is determined by the suppressed diffusivity of the reactants for L≪l.

Hydrodynamically enforced entropic trapping of Brownian particles.

We study the transport of Brownian particles through a corrugated channel caused by a force field containing curl-free (scalar potential) and divergence-free (vector potential) parts. We develop a generalized Fick-Jacobs approach leading to an effective one-dimensional description involving the potential of mean force. As an application, the interplay of a pressure-driven flow and an oppositely oriented constant bias is considered. We show that for certain parameters, the particle diffusion is significantly suppressed via the property of hydrodynamically enforced entropic particle trapping.

[Acute care of critically ill children in general hospitals: organisation and training]. / Acute opvang van kinderen in algemene ziekenhuizen.

OBJECTIVE: To gain insight into how the acute care of critically ill children at general hospitals is organised, whether staff is sufficiently trained and whether the necessary materials and medications are present. DESIGN: Questionnaire combined with a site visit. METHOD: Questionnaires were sent to all primarily involved specialists (emergency room specialists and paediatricians), and to the auxiliary anaesthetists and intensivists involved, at the nine general hospitals in Southeast Netherlands. Two researchers performed standardised interviews with the lead paediatricians on site and checked for materials and medication present in the emergency and paediatric departments. RESULTS: Of the 195 questionnaires sent, 97 (49.7%) were deemed suitable for analysis. The response from the primary specialists involved (77.6%) was more than twice that of the auxiliary specialists (31.9%). At 7 hospitals, verbal agreements on the organisation of acute care were maintained, 1 hospital had a written protocol, and 2 hospitals had a task force addressing this topic. One out of 5 respondents was unaware of the verbal agreements and 1 out of 3 mistakenly assumed that a protocol existed. Two out of 3 primary specialists involved were certified for Advanced Paediatric Life Support (APLS); 1 out of 13 of the auxiliary specialists had such a certificate. Scenario training was being conducted at 8 hospitals. A paediatric resuscitation cart was available at both the emergency and paediatric departments of 8 hospitals, 3 of which were fully stocked at both departments. Laryngeal mask airways and PEEP-valves (Positive End Expiratory Pressure) were lacking at 6 of the 9 hospitals. The medication stock was complete at all the hospitals. CONCLUSION: The organisation of and training for the acute care of critically ill children and presence of materials - the aspects we investigated - need attention at all general hospitals evaluated. It appeared that many specialists are not APLS certified and written protocols concerning organisation and training were lacking. The establishment of a task force responsible for the acute care of children is one measure that could result in rapid improvement. Another measure could be the introduction of a standardised list of inventory needed for acute care.

Tuning the magnetic anisotropy of Co-Ni nanowires: comparison between single nanowires and nanowire arrays in hard-anodic aluminum oxide membranes.

Co(x)Ni(1-x) alloy nanowires with varying Co content (0 ≤ x ≤ 0.95), having a diameter of 130 nm and length of around 20 µm, are synthesized by template-assisted electrodeposition into the nanopores of SiO(2) conformal coated hard-anodic aluminum oxide membranes. The magneto-structural properties of both single isolated nanowires and hexagonally ordered nanowire arrays of Co-Ni alloys are systematically studied by means of magneto-optical Kerr effect magnetometry and vibrating sample magnetometry, respectively, allowing us to compare different alloy compositions and to distinguish between the magnetostatic and magnetocrystalline contributions to the effective magnetic anisotropy for each system. The excellent tunable soft magnetic properties and magnetic bistability exhibited by low Co content Co-Ni nanowires indicate that they might become the material of choice for the development of nanostructured magnetic systems and devices as an alternative to Fe-Ni alloy based systems, being chemically more robust. Furthermore, Co contents higher than 51 at.% allow us to modify the magnetic behavior of Co-rich nanowires by developing well controlled magnetocrystalline anisotropy, which is desirable for data storage applications.

Driven Brownian transport through arrays of symmetric obstacles.

We numerically investigate the transport of a suspended overdamped Brownian particle which is driven through a two-dimensional rectangular array of circular obstacles with finite radius. Two limiting cases are considered in detail, namely, when the constant drive is parallel to the principal or the diagonal array axes. This corresponds to studying the Brownian transport in periodic channels with reflecting walls of different topologies. The mobility and diffusivity of the transported particles in such channels are determined as functions of the drive and the array geometric parameters. Prominent transport features, like negative differential mobilities, excess diffusion peaks, and unconventional asymptotic behaviors, are explained in terms of two distinct lengths, the size of single obstacles (trapping length), and the lattice constant of the array (local correlation length). Local correlation effects are further analyzed by continuously rotating the drive between the two limiting orientations.

Communication: impact of inertia on biased Brownian transport in confined geometries.

We consider the impact of inertia on biased Brownian motion of point-size particles in a two-dimensional channel with sinusoidally varying width. If the time scales of the problem separate, the adiabatic elimination of the transverse degrees of freedom leads to an effective description for the motion along the channel given by the potential of mean force. The possibility of such description is intimately connected with equipartition. Numerical simulations show that in the presence of external bias the equipartition may break down leading to non-monotonic dependence of mobility on external force and several other interesting effects.