Christoph M. Happel

Synthesis, structure and comparison of the DNA cleavage ability of metal complexes M(II)L with the N-(2-ethoxyethanol)-bis(2-picolyl)amine ligand L (M = Co, Ni, Cu and Zn)

Complexes of a N,N-bis(2-picolyl)amine (bpa) derivative with a pendant ethoxyethanol side chain (bpa(CH2)2O(CH2)2OH) (1) with late divalent transition metal ions Co(II), Ni(II), Cu(II) and Zn(II) have been studied. All complexes, [[bpa(CH2)2O(CH2)2OH]Co(NO3)](NO3) (1Co), [[bpa(CH2)2O(CH2)2OH]Ni(NO3)](NO3) (1Ni), [[bpa(CH2)2O(CH2)2OH]Cu(H2O)(NO3)](NO3) (1Cu) and [[bpa(CH2)2O(CH2)2OH]Zn(NO3)](NO3) (1Zn), were comprehensively characterized and their X-ray single crystal structures have been determined. The complexes show hexacoordinated geometries, in which 1 acts as a tetradentate (1Cu) or pentadentate (1Co, 1Ni and 1Zn) ligand. DNA cleavage experiments have been performed on supercoiled double stranded DNA plasmids in order to compare the cleavage efficiency of all four metals in the same ligand environment of 1. In this assay, 1Co and 1Cu showed the highest cleavage efficiency, whereas 1Ni and 1Zn were virtually inactive. Quantification of the gel electrophoresis bands showed that more than 80% of the plasmid has suffered at least one single strand cut in the case of 1Cu, and about 50% of the plasmid was nicked by 1Co. The differential cleavage activity is discussed in relation to the structural findings and a mechanism is proposed for 1Cu.

Rotationally acquired four-dimensional optical coherence tomography of embryonic chick hearts using retrospective gating on the common central A-scan

We introduce a new method of rotational image acquisition for four-dimensional (4D) optical coherence tomography (OCT) of beating embryonic chick hearts. The rotational axis and the central A-scan of the OCT are identical. An out-of-phase image sequence covering multiple heartbeats is acquired at every angle of an incremental rotation of the deflection mirrors of the OCT system. Image acquisition is accomplished after a rotation of 180°. Comparison of a displayed live M-mode of the central A-scan with a reference M-mode allows instant detection of translational movements of the embryo. For calculation of 4D data sets, we apply an image-based retrospective gating algorithm using the phase information of the common central A-scan present in all acquired images. This leads to cylindrical three-dimensional data sets for every time step of the cardiac cycle that can be used for 4D visualization. We demonstrate this approach and provide a video of a beating Hamburger and Hamilton stage 16 embryonic chick heart generated from a 4D OCT data set using rotational image acquisition.

A detailed atlas of chick heart development in vivo.

Various model organisms such as mouse, xenopus, or zebrafish embryos have been studied in the past to gain insight into the complex processes driving normal and abnormal development of the vertebrate heart. Despite the fact that the chicken embryo has been a favored classic model system used by embryologists and cardiovascular scientists for centuries to illustrate the principles of basic vertebrate embryology and cardiovascular development, so far, no one has provided a thorough documentation of heart development in this model from early visual stages to the stage of a completely formed heart with (a) images and (b) video recordings of beating hearts. However, in vivo documentation of heart development stages is indispensable because the initially tubular embryonic heart not only undergoes dramatic morphological changes, but also intriguing functional changes during cardiogenesis, which, only if they follow and remain within the normal developmental pathway, lead to the establishment of the normal four-chambered heart. In this work we present the first reference catalogue of cardiac development in vivo with (1) 25 plates of high resolution colour images in different views from Hamburger-Hamilton (HH)-stage 12 (day 2, relatively straight heart tube, early myocardial contractions) through HH-stage 35 (day 9, four-chambered heart) in end-diastole and end-systole, including a plate with an overview of all these stages; (2) collection of 82 video recordings of beating hearts in different views corresponding to the stages shown in the plates.

Integration of an optical coherence tomography (OCT) system into an examination incubator to facilitate in vivo imaging of cardiovascular development in higher vertebrate embryos under stable physiological conditions

High-resolution in vivo imaging of higher vertebrate embryos over short or long time periods under constant physiological conditions is a technically challenging task for researchers working on cardiovascular development. In chick embryos, for example, various studies have shown that without appropriate maintenance of temperature, as one of the main environmental factors, the embryonic heart rate drops rapidly and often results in an increase in regurgitant flow. Hemodynamic parameters are critical stimuli for cardiovascular development that, for a correct evaluation of their developmental significance, should be documented under physiological conditions. However, previous studies were mostly carried out outside of an incubator or under suboptimal environmental conditions. Here we present, to the best of our knowledge, the first detailed description of an optical coherence tomography (OCT) system integrated into an examination incubator to facilitate real-time in vivo imaging of cardiovascular development under physiological environmental conditions. We demonstrate the suitability of this OCT examination incubator unit for use in cardiovascular development studies by examples of proof of principle experiments. We, furthermore, point out the need for use of examination incubators for physiological OCT examinations by documenting the effects of room climate (22°C) on the performance of the cardiovascular system of chick embryos (HH-stages 16/17). Upon exposure to room climate, chick embryos showed a fast drop in the heart rate and striking changes in the cardiac contraction behaviour and the blood flow through the vitelline circulation. We have documented these changes for the first time by M-mode OCT and Doppler M-mode OCT.

Non-destructive, High-resolution 3-dimensional Visualization of a Cardiac Defect in the Chick Embryo Resembling Complex Heart Defect in Humans Using Micro-computed Tomography: Double Outlet Right Ventricle With Left Juxtaposition of Atrial Appendages

Nondestructive, high-resolution 3-dimensional (3D) imaging of the embryonic heart remains a challenge in cardiovascular development research. In the past, several imaging techniques (eg, magnetic resonance microscopy, optical coherence tomography) were tested for their suitability to visualize the 3D morphology of embryonic hearts. Most of these imaging tools have their drawbacks with respect to resolution and depth penetration. Here we present, to the best of our knowledge, the first high-resolution 3D images of normal and malformed embryonic chick hearts at the 10 μm level generated by microcomputed tomography (micro-CT) examination of critical point-dried heart specimens. Cardiac anatomy is demonstrated in great details with respect to myocardial fiber arrangement and trabeculations as well as atrioventricular (AV) and semilunar valves. Positions of great vessels with associated ventricular septal defects are visualized in high quality in malformed hearts. Figure 1A shows the normal 4-chambered heart of a day 9 chick embryo with correct positioning of the heart chambers and great vessels. Figure 1B depicts an image of a malformed embryonic chick heart in which both great arteries are significantly shifted toward the right side with extreme dextroposition of the aorta, and both great arteries arise from the right ventricle (double outlet right ventricle [DORV]). Note also that both atrial appendages are located to the left of the great arteries (left juxtaposition of atrial appendages [LJAA]). The cardiac defect that we present here in the chick embryo resembles a rare complex heart defect known in humans, as depicted in a classic drawing by Frank Netter, MD, in the Netter Collection of Medical Illustrations – Heart (Figure 1C, reproduced with permission from netterimages.com). Figure 1. Photographs of day 9 embryonic chick hearts (A and B, respectively) and a drawing of a malformed human …

Levosimendan for bridging in a pediatric patient with Alström syndrome awaiting heart-lung transplantation

recessive inherited disease marked by retinal degeneration combined with obesity, diabetes mellitus, neurogenous deafness and dilated cardiomyopathy leading to congestive heart failure in childhood or adolescence [1]. In case of progressive heart failure despite of intensified conventional therapy transplantation may become the final therapeutic option. However, if combined heart–lung transplantation (HLTx) is intended because of high pulmonary vascular resistance the long wait necessitates an extended treatment for bridging to transplantation. Among the suitable drugs the calcium sensitizer levosimendan should be considered because of the positive effect in the treatment of cardiomyopathy in adults which has been described before [2, 3]. Although the reuse of levosimendan in children has rarely been investigated, a few number of studies indicate a positive effect, too [4, 5]. However, there are, to the best of our knowledge, no reports on the repeated use of levosimendan for bridging in pediatric patients awaiting HLTx.

Jacobsen syndrome and Beckwith-Wiedemann syndrome caused by a parental pericentric inversion inv(11)(p15q24).

Here we report on a male infant presenting the typical pattern of Jacobsen syndrome including trigonocephaly, thrombocytopenia, congenital heart defect, urethral stenosis, and partial agenesis of the corpus callosum. Conventional karyotyping, FISH, SKY and CGH analyses showed that the region distal to the MLL locus on 11q23 was lost and replaced by the distal region of 11p, leading to a partial trisomy of 11p and a partial monosomy of 11q. According to ISCN (1995) the karyotype can be described as 46,XY,add(11)(q2?3). ish 11ptel(D11S2071x3),11qtel(VIJyRM2072x1). Array‐CGH analysis allowed us to narrow down the breakpoints to 11p15.1 and 11q24.1. Methylation analyses of genes located on 11p showed an increased level of the non‐methylated paternal allele of the KCNQ1OT1 gene, confirming the concomitant presence of Beckwith‐Wiedemann syndrome (BWS). The phenotype resulting from the 11q deletion seems to dominate the phenotype due to the distal 11p trisomy. Investigation of the parents revealed that this chromosomal rearrangement was caused by a paternal pericentric inversion inv(11)(p15q24).

A new modified Seldinger technique for 2-and 3-French peripherally inserted central venous catheters

This study describes a modified Seldinger technique for 2- and 3-French peripherally inserted central venous catheters: A device similar to that used in heart catherisation with a standard micro-introducer serving as sheath and an arterial catheter serving as inner dilator was pushed forward over a wire guide that had before been inserted via a peripheral venous catheter. With this method 2-and 3-French catheters could be safely inserted into peripheral veins of 14 paediatric patients. In conclusion successful insertion of a small peripheral venous catheter offers in most cases a possibility for the placement of a central venous line.

Neonatal aortic arch thrombosis: analysis of thrombophilic risk factors and prognosis.

UNLABELLED Arterial thrombosis in neonates and children is a rare event and is often associated with external risk factors such as asphyxia or sepsis. We report our experiences with two neonates with spontaneous aortic arch thrombosis mimicking aortic coarctation. Despite single case reports until now, no data exist for the underlying thrombophilic risk factors and prognosis of this rare event. Both patients were carriers of a heterozygous factor V Leiden mutation, which has been reported once before as a risk factor for aortic arch thrombosis. One of our patients was operated upon successfully and is alive. The second patient suffered a large infarction of the right medial cerebral artery and had a thrombotic occlusion of the inferior caval vein. The patient obtained palliative care and died at the age of 6 days. In the literature, we identified 19 patients with neonatal aortic arch thrombosis. Of the 19 patients, 11 (58%) died. Including the two reported patients, the mortality rate of patients with multiple thromboses was 80% (8/10) compared with 18% (2/11) for patients with isolated aortic arch thrombosis; this difference reached statistical significance (p = 0.009). The analysis of thrombophilic disorders revealed that factor V Leiden mutation and protein C deficiency seem to be the most common risk factors for aortic arch thrombosis. CONCLUSION Neonatal aortic arch thrombosis is a very rare but life-threatening event, with a high rate of mortality, especially if additional thrombotic complications are present. Factor V Leiden mutation seems to be one important risk factor in the pathogenesis of this fatal disease.

First-in-child use of the oral soluble guanylate cyclase stimulator riociguat in pulmonary arterial hypertension:

Riociguat has been approved for use in adults with pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension. No clinical data on its therapeutic use in children with PAH are currently available. We report the case of a now four-year-old boy who initially presented at the age of 10 months with suprasystemic pulmonary hypertension (PH) and right ventricular (RV) failure, vomiting, peripheral cyanosis, and failure to thrive. Cardiac catheterization revealed severe PAH. At radiologic suspicion of interstitial lung disease, repeated CT scan and an open lung biopsy were performed but could not clarify the entity of PAH. Given the demonstrated vasoreactivity, the boy was started on the calcium channel blocker amlodipine, in combination with the endothelin-1 receptor antagonist bosentan. Two years later, based on persistently systemic PAH with lost vasoreactivity, PAH therapy was changed to bosentan and phosphodiesterase-5 inhibitor sildenafil. No significant improvement on the aforementioned therapy was seen, so that the patient was referred to our institution. Invasive hemodynamic evaluation showed suprasystemic PAH and marked acute vasoreactivity (PAP 127/103/83 mmHg, PVRi 23.48 WU·m2 and PVR/SVR ratio 1.59 at baseline vs. PVRi 5.89 WU·m2 and PVR/SVR ratio 0.93 under O2/NO). Subsequently, we switched the patient from sildenafil to riociguat. After six months on bosentan/riociguat, the patient showed a marked decrease in PVR/SVR and transpulmonary pressure gradients, in RV hypertrophy, PA acceleration time, and left ventricular-eccentricity index. Clinically, the patient improved in pediatric functional class from 2/3 to 1. In conclusion, off-label use of oral riociguat may be considered in selected children with severe PAH.