Repair of pulmonary artery sling with tracheal and intracardiac defects

BACKGROUND

Pulmonary artery sling is commonly associated with tracheal stenosis and intracardiac anomalies. While surgical repair is standardized, coexistent anomalies often determine outcomes. With the paucity of risk stratification, this study aimed to review our experience and stratify risk factors for the surgical outcome of complex pulmonary artery sling repair in the presence of airway or intracardiac lesions.

METHODS

Seventy-nine consecutive children with pulmonary artery sling were evaluated retrospectively following surgical repair. Median age at surgery was 5 months (interquartile range 3-9). Surgical approaches included pulmonary artery sling alone (n = 10), pulmonary artery sling with tracheoplasty (n = 41), and pulmonary artery sling with both intracardiac and tracheal surgery (n = 28).

RESULTS

There were 7 early (8.8%) deaths. Two patients after left pulmonary artery reimplantation needed revision of the anastomosis. The median intensive care and hospital stay were 11 (interquartile range 9.2-24.8) and 17.9 (interquartile range 4.3-19.8) days, and considerably longer when associated tracheal surgery (p = 0.002). Follow-up was complete in 66/69 and 3 (3.8%) children died late: 2.7, 10.2, and 17 months after surgery. Univariate analysis showed abnormal lung and coexisting structural heart disease as risk factors. Multivariate analysis revealed total cardiopulmonary bypass time as an independent predictor of overall mortality.

CONCLUSION

Complex pulmonary artery sling repair can be performed with a good surgical outcomes even when associated with airway malformations or structural heart diseases. Lung abnormality and longer cardiopulmonary bypass time as a surrogate marker of complex surgery, are possible risk factors.

Sensor Measures of Affective Leaning

The aim of this study was to predict self-report data for self-regulated learning with sensor data. In a longitudinal study multichannel data were collected: self-report data with questionnaires and embedded experience samples as well as sensor data like electrodermal activity (EDA) and electroencephalography (EEG). 100 students from a private university in Germany performed a learning experiment followed by final measures of intrinsic motivation, self-efficacy and gained knowledge. During the learning experiment psychophysiological data like EEG were combined with embedded experience sampling measuring motivational states like affect and interest every 270 s. Results of machine learning models show that consumer grade wearables for EEG and EDA failed to predict embedded experience sampling. EDA failed to predict outcome measures as well. This gap can be explained by some major technical difficulties, especially by lower quality of the electrodes. Nevertheless, an average activation of all EEG bands at T7 (left-hemispheric, lateral) can predict lower intrinsic motivation as outcome measure. This is in line with the personality system interactions (PSI) theory of Julius Kuhl. With more advanced sensor measures it might be possible to track affective learning in an unobtrusive way and support micro-adaptation in a digital learning environment.

Acute Type A Aortic Dissection Complicated by COVID-19 Infection

A patient underwent surgery for acute type A aortic dissection. Testing for SARS-CoV-2 was positive. The postoperative course was complicated by a mixed viral and bacterial pneumonia with bilateral infiltration, treated with antibiotics and hydroxychloroquine, without any need for reintubation. The patient recovered and finally could be discharged. This report shows the feasibility for surgical treatment of acute aortic disease in patients with COVID-19.

Deep hypothermic extracorporeal membrane oxygenation cannula exchange in a child with necrotic pneumonia

Necrotizing pneumonia can lead to respiratory insufficiency in previously healthy children. Extracorporeal membrane oxygenation can be used for hemodynamic salvage and subsequent lung rest awaiting recovery. We present a case of a child initially placed on veno-arterial extracorporeal membrane oxygenation and converted to veno-venous extracorporeal membrane oxygenation. This was done under deep hypothermia in the operating theater.

Technical challenges of lung transplantation in children after arterial switch operation

Pulmonary arterial hypertension after arterial switch operation for transposition of the great arteries is rare. Lung transplantation can be the last option in cases of failed medical therapy. We report 2 paediatric patients who underwent lung transplantation for this indication. Altered hilar anatomy, mediastinal adhesions and haemostatic control represent the main technical challenges. Volume-reduction surgery is sometimes necessary to address altered cardiopulmonary relationships while expanding the donor pool.

Ten-year results of aortic valve replacement with first-generation Mitroflow bioprosthesis: is early degeneration a structural or a technical issue?

OBJECTIVES

Concerns have been raised about the durability of the first-generation Mitroflow aortic bioprosthesis (model 12 A-LX) due to the lack of anticalcification treatment. This study reflects a 10-year experience with this prosthesis for aortic valve replacement.

METHODS

From June 2003 to May 2012, the Mitroflow prosthesis was used for aortic valve replacement in 510 patients, of whom only 467 with complete clinical follow-up were included for analysis. Study end-points were survival and incidence of structural valve degeneration (SVD). Analysis of SVD was based on cumulative incidence function and competing-risk Cox regression.

RESULTS

The mean patient age was 76.4 ± 6.1 years. Valve sizes from 23 to 25 were used in 70.4%, whereas sizes from 19 to 21 were used in only 19.2%, thereby avoiding patient-prosthesis mismatch in 89.1%. Within a median follow-up time of 6.6 years (interquartile range 4.4), a cumulative 2375 patient-years, the survival rate was 86.2%, 67.3% and 33.3% at 1, 5 and 10 years, respectively. The cumulative incidence of SVD, with death as a competing risk, was 0%, 0.7% and 6.2% at 1, 5 and 10 years, respectively. Only age <75 years tended to affect the late hazard of SVD (hazard ratio 0.50, 95% confidence interval 0.23-1.08, P  = 0.08), regardless of valve-specific issues.

CONCLUSIONS

The data do not support the concerns about early accelerated structural degeneration of the first-generation Mitroflow bioprosthesis used for aortic valve replacement in patients older than 75 years. We postulate that limiting the number of small prostheses using a proper implantation technique has enhanced the reduction in risk of significant patient-prosthesis mismatch as the main determinant of early SVD.

Minimally Invasive Repair of Mitral Valve Prolapse and Concomitant Atrial Fibrillation Ablation in a Heart Transplant

Significant mitral valve disease with atrial fibrillation after heart transplantation is unusual. We report the diagnosis and minimally invasive surgical treatment 17 years after transplantation, in which mitral valve repair together with left atrial ablation was performed, resulting in a satisfying clinical and echocardiographic improvement.

Stealth monoolein-based nanocarriers for delivery of siRNA to cancer cells

While the delivery of small interfering RNAs (siRNAs) is an attractive strategy to treat several clinical conditions, siRNA-nanocarriers' stability after intravenous administration is still a major obstacle for the development of RNA-interference based therapies. But, although the need for stability is well recognized, the notion that strong stabilization can decrease nanocarriers' efficiency is sometimes neglected. In this work we evaluated two stealth functionalization strategies to stabilize the previously validated dioctadecyldimethylammonium bromide (DODAB):monoolein (MO) siRNA-lipoplexes. The nanocarriers were pre- and post-pegylated, forming vectors with different stabilities in biological fluids. The stealth nanocarriers' behavior was tested under biological mimetic conditions, as the production of stable siRNA-lipoplexes is determinant to achieve efficient intravenous siRNA delivery to cancer cells. Upon incubation in human serum for 2h, by fluorescence Single Particle Tracking microscopy, PEG-coated lipoplexes were found to have better colloidal stability as they could maintain a relatively stable size. In addition, using fluorescence fluctuation spectroscopy, post-pegylation also proved to avoid siRNA dissociation from the nanocarriers in human serum. Concomitantly it was found that PEG-coated lipoplexes improved cellular uptake and transfection efficiency in H1299 cells, and had the ability to silence BCR-ABL, affecting the survival of K562 cells. Based on an efficient cellular internalization, good silencing effect, good siRNA retention and good colloidal stability in human serum, DODAB:MO (2:1) siRNA-lipoplexes coated with PEG-Cer are considered promising nanocarriers for further in vivo validation.

STATEMENT OF SIGNIFICANCE

This work describes two stealth functionalization strategies for the stabilization of the previously validated dioctadecyldimethylammonium bromide (DODAB):monoolein (MO) siRNA-lipoplexes. These nanocarriers are capable of efficiently incorporating and delivering siRNA molecules to cells in order to silence genes whose expression is implicated in a pathological condition. The main objective was to functionalize these nanocarriers with a coating conferring protection to siRNA in blood without compromising its efficient delivery to cancer cells, validating the potential of DODAB:MO (2:1) siRNA-lipoplexes as therapeutic vectors. We show that the stealth strategy is determinant to achieve a stable and efficient nanocarrier, and that DODAB:MO mixtures have a very promising potential for systemic siRNA delivery to leukemic cells.

A Three-Dimensional Skeletal Reconstruction of the Stem Amniote Orobates pabsti (Diadectidae): Analyses of Body Mass, Centre of Mass Position, and Joint Mobility

Orobates pabsti, a basal diadectid from the lower Permian, is a key fossil for the understanding of early amniote evolution. Quantitative analysis of anatomical information suffers from fragmentation of fossil bones, plastic deformation due to diagenetic processes and fragile preservation within surrounding rock matrix, preventing further biomechanical investigation. Here we describe the steps taken to digitally reconstruct MNG 10181, the holotype specimen of Orobates pabsti, and subsequently use the digital reconstruction to assess body mass, position of the centre of mass in individual segments as well as the whole animal, and study joint mobility in the shoulder and hip joints. The shape of most fossil bone fragments could be recovered from micro-focus computed tomography scans. This also revealed structures that were hitherto hidden within the rock matrix. However, parts of the axial skeleton had to be modelled using relevant isolated bones from the same locality as templates. Based on the digital fossil, mass of MNG 10181 was estimated using a model of body shape that was varied within a plausible range to account for uncertainties of the dimension. In the mean estimate model the specimen had an estimated mass of circa 4 kg. Varying of the mass distribution amongst body segments further revealed that Orobates carried most of its weight on the hind limbs. Mostly unrestricted joint morphology further suggested that MNG 10181 was able to effectively generate propulsion with the pelvic limbs. The digital reconstruction is made available for future biomechanical studies.

Single-particle tracking for studying nanomaterial dynamics: applications and fundamentals in drug delivery

Many macromolecular therapeutics could potentially treat genetic disorders and cancer. They have, however, not yet reached the clinical stage owing to a lack of suitable carriers that can bring the therapeutics from the administration site to the subcellular site in target cells. One of the reasons that is hindering the development of such carriers is the limited knowledge of their transport dynamics and intracellular processing. Single-particle tracking (SPT) microscopy, thanks to its single molecule sensitivity and its broad applicability, has found its entry in the field of drug delivery to get an answer to these questions. This review aims to introduce the fundamentals of SPT to the drug delivery community and highlight the most recent discoveries obtained with SPT in the field of drug delivery.

Spindle cell sarcoma of the mitral valve: an unusual cause of acute coronary syndrome in a child

We present an unusual case of acute myocardial infarction by embolic obstruction of both the left anterior descending and right coronary arteries in a 14-year-old girl. Echocardiography showed mobile lesions on the mitral valve and into the left ventricular outflow tract with poor left ventricular function, eventually suggesting endocarditis. Successful surgery comprised mitral valve plasty after complete resection of the tumoral lesion, in association with coronary artery embolectomy. Histologic examination revealed a malignant spindle cell sarcoma treated with adjuvant chemotherapy. We emphasize here the differential diagnosis of acute coronary syndrome in children by a rare cardiac tumor.

Meso-Rex shunt using deep femoral vein conduit: first report

The Meso-Rex shunt (MRS) procedure was first described in 1992 by de VILLE et al. for the treatment of extrahepatic portal vein obstruction (EHPVO) in paediatric liver transplant patients. This technique provides more physiological relief of portal hypertension compared to the porto-systemic shunts, which can lead to long-term complications such as hyperammonaemia and hepato-pulmonary syndrome. Different conduits as autologous and cryopreserved veins or prosthetic grafts have been previously reported. We present herein the first case of a MRS using the autologous deep femoral vein in a 17-year-old female patient affected by EHPVO from unknown reasons.

Correlation of dual colour single particle trajectories for improved detection and analysis of interactions in living cells

Interactions between objects inside living cells are often investigated by looking for colocalization between fluorescence microscopy images that are recorded in separate colours corresponding to the fluorescent label of each object. The fundamental limitation of this approach in the case of dynamic objects is that coincidental colocalization cannot be distinguished from true interaction. Instead, correlation between motion trajectories obtained by dual colour single particle tracking provides a much stronger indication of interaction. However, frequently occurring phenomena in living cells, such as immobile phases or transient interactions, can limit the correlation to small parts of the trajectories. The method presented here, developed for the detection of interaction, is based on the correlation inside a window that is scanned along the trajectories, covering different subsets of the positions. This scanning window method was validated by simulations and, as an experimental proof of concept, it was applied to the investigation of the intracellular trafficking of polymeric gene complexes by endosomes in living retinal pigment epithelium cells, which is of interest to ocular gene therapy.

Automatic particle detection in microscopy using temporal correlations

One of the fundamental problems in the analysis of single particle tracking data is the detection of individual particle positions from microscopy images. Distinguishing true particles from noise with a minimum of false positives and false negatives is an important step that will have substantial impact on all further analysis of the data. A common approach is to obtain a plausible set of particles from a larger set of candidate particles by filtering using manually selected threshold values for intensity, size, shape, and other parameters describing a particle. This introduces subjectivity into the analysis and hinders reproducibility. In this paper, we introduce a method for automatic selection of these threshold values based on maximizing temporal correlations in particle count time series. We use Markov Chain Monte Carlo to find the threshold values corresponding to the maximum correlation, and we study several experimental data sets to assess the performance of the method in practice by comparing manually selected threshold values from several independent experts with automatically selected threshold values. We conclude that the method produces useful results, reducing subjectivity and the need for manual intervention, a great benefit being its easy integratability into many already existing particle detection algorithms.