Aortic arch reconstruction in surgical treatment of ascending aortic aneurysms and dissections

<p><strong>Aim.</strong> The study focused on the analysis of short-term results of aortic arch reconstruction in patients undergoing open heart surgery for ascending aortic aneurysms and dissections, comparison of intra-operative brain protection methods and verification of predictors of complications.<br /><strong>Methods.</strong> 84 patients (mean age 55.5 ± 11.5 years, 72.6 % (61) males) with ascending aortic aneurysms and Stanford type A ascending aortic and arch dissections underwent surgery over a period from January, 2013, to March, 2015. Patients were divided into 3 groups. The 1st group included patients with ascending aortic aneurysm combined with aortic dilatation at the level of innominate artery &gt;4.0 cm (n = 41). The 2nd group consisted of patients with Stanford type A acute ascending aortic and arch dissection (n = 25). In the 3rd group there were patients with type A chronic ascending aortic and arch dissection (n = 18). No significant differences between the groups were observed. Mean values of the maximum ascending aortic diameter did not differ significantly and were 59.6, 58.4 and 62.4 mm in the 1st, 2nd and 3rd groups, respectively. 3 patients from the 2nd group presented with acute heart failure, 6 – acute myocardial infarction, and 3 – stroke. Higher values of pressure gradient on the aortic valve were registered in the 1st group, as compared to those in the 2nd and 3rd groups (mean value of the peak gradient was 4.5, 8.1 and 12.4 mm Hg, respectively). EuroSCORE II value in the 1st , 2nd and 3rd groups was 9.4 %, 17.7 % and 5.8 %, respectively. <br /><strong>Results.</strong> Overall hospital mortality was 1.2 %: 1 patient with acute type A aortic dissection and later dissection of innominate artery developed stroke and died due to multiple organ failure. More prolonged cardiopulmonary bypass time and aortic cross-clamp time were required for patients with acute ascending aortic dissections, but the total surgery time and circulatory arrest time differed significantly only in the 2nd and 3rd groups. Lengthy inotropic support, ventilation time and total ICU stay, as well as a higher rate of neurologic disorders in patients with aortic dissections in comparison with patients with aneurysms were observed. We verified correlation of the urgent type of surgery, acute type A aortic dissection, including arch and descending thoracic aortic dissection, also with dissection of cervicocerebral arteries, with a more complicated hospital period, increased inotropic support and prolonged duration of stay in the intensive care unit.<br /><strong>Conclusion</strong>. Hemiarch repair of aortic arch dilatation in case of ascending aortic replacement is an effective and safe method of treatment of extended ascending aortic aneurysms and dissections. Unilateral anterograde cerebral perfusion with simultaneous crossclamping of contralateral common carotid artery allows to maintain effective cerebral protection in conditions of moderate hypothermia and duration of circulatory arrest for at least 30-40 minutes. Adverse prognostic factors are urgent surgery, ascending aortic, arch and descending thoracic aortic dissection, prolonged extracorporeal circulation and myocardial ischemia, and disuse of the axillary artery for cannulation.</p><p>Received 6 October 2016. Accepted 24 November 2016.</p><p><strong>Funding:</strong> The study was carried out within the government’s task for 2015-2017, “Cardiovascular pathologies”, theme No. 4 “Research on genome and cellular mechanisms of formation of aorta and aortic valve pathology and development of new methods for its treatment including hybrid technologies”.<br /><strong>Conflict of interest:</strong> The authors declare no conflict of interest.<br /><strong>Author contributions</strong><br />Material acquisition and analysis: Gordeev M.L., Uspenskiy V.E., Bakanov A.Y., Volkov V.V., Ibragimov A.N., Scherbinin T.S., Irtyuga O.B., Naimushin A.V. <br />Article writing: Gordeev M.L., Uspenskiy V.E., Bakanov A.Y. <br />Review &amp; editing: Gordeev M.L., Naimushin A.V.<br /><strong>Acknowledgment</strong><br />The authors express their gratitude for support in diagnostics and management of patients with aortic abnormalities to I. V. Basek, PhD, Head of X-Ray CT Department, and to the employees of X-ray CT Department; to D.A. Zverev, PhD, Head of X-ray Endovascular Surgery Research Lab and the employees of X-ray Endovascular Surgery Departments; O.M. Moiseyeva, Doc. Sci. (Medicine), Head of Noncoronarogenic Heart Diseases Department and her employees, as well as to the employees of Anesthesiology &amp; Resuscitation and Cardiovascular Surgery Departments.</p>

Structure and Functions of the Mediator Complex

Mediator is a key factor in the regulation of expression of RNA polymerase II-transcribed genes. Recent studies have shown that Mediator acts as a coordinator of transcription activation and participates in maintaining chromatin architecture in the cell nucleus. In this review, we present current concepts on the structure and functions of Mediator.

Super-Resolution Microscopy in Studying the Structure and Function of the Cell Nucleus

In recent decades, novel microscopic methods commonly referred to as super- resolution microscopy have been developed. These methods enable the visualization of a cell with a resolution of up to 10 nm. The application of these methods is of great interest in studying the structure and function of the cell nucleus. The review describes the main achievements in this field.

The Variable CTCF Site from Drosophila melanogaster Ubx Gene is Redundant and Has no Insulator Activity

CTCF is the most thoroughly studied chromatin architectural protein and it is found in both Drosophila and mammals. CTCF preferentially binds to promoters and insulators and is thought to facilitate formation of chromatin loops. In a subset of sites, CTCF binding depends on the epigenetic status of the surrounding chromatin. One such variable CTCF site (vCTCF) was found in the intron of the Ubx gene, in close proximity to the BRE and abx enhancers. CTCF binds to the variable site in tissues where Ubx gene is active, suggesting that the vCTCF site plays a role in facilitating contacts between the Ubx promoter and its enhancers. Using CRISPR/Cas9 and attP/attB site-specific integration methods, we investigated the functional role of vCTCF and showed that it is not required for normal Drosophila development. Furthermore, a 2161-bp fragment containing vCTCF does not function as an effective insulator when substituted for the Fab-7 boundary in the Bithorax complex. Our results suggest that vCTCF function is redundant in the regulation of Ubx.

Erratum to: The Variable CTCF Site from Drosophila melanogaster Ubx Gene is Redundant and Has no Insulator Activity

An Erratum to this paper has been published: https://doi.org/10.1134/S1607672955340024

Super-Resolution Microscopy in Studying the Structure and Function of the Cell Nucleus

In recent decades, novel microscopic methods commonly referred to as super- resolution microscopy have been developed. These methods enable the visualization of a cell with a resolution of up to 10 nm. The application of these methods is of great interest in studying the structure and function of the cell nucleus. The review describes the main achievements in this field.