Sliding tracheoplasty of complete tracheal cartilage rings in children.

INTRODUCTION: Complete tracheal rings are a rare malformation that occurs in 1 out of 100,000 live births. It is rare, isolated tracheal or tracheobronchial anomaly developed due to abnormal cartilage growth with formation of complete ring and often resulting in airway stenosis. Slide tracheoplasty, as it was originally described by Tsang et al. and popularized by Grillo et al., overlaps stenotic segments of trachea, shortening trachea itself, thus, doubling the circumference and diameter of the stenotic area. MATERIALS AND METHODS: We have performed slide tracheoplasty in 12 children during the period of 2019-2021 in thoracic surgery department of our center. Median age was 15 ± 21,1 months (2 months-6 years),median weight - 8,04 ± 4,75 kg (3-20,7 kg),tracheal lumen varied from 2.5 to 3.0 mm, stenosis length - from 40 to 70% of the trachea length. RESULTS: Slide tracheoplasty was performed using central veno-arterial extracorporeal membrane oxygenation in 7 cases and using cardiopulmonary bypass in 5 cases. Concomitant heart disease was revealed in 5 children (pulmonary artery sling in 3 cases, ventricular septal defects - 1, aberrant subclavian artery -1). 5 children underwent one-stage correction of VSD: plastic VSD -1; left pulmonary artery reimplantation - 3; subclavian artery reimplantation - 1. All patients were on mechanical ventilation for 4,3 ± 2,78 days at postoperative period. Patients were discharged 16,3 ± 5,14 days after surgery. Satisfactory result of treatment in the form of respiratory failure relief was achieved in 10 patients. It was possible to increase the trachea lumen from 1.5 to 2 times in all cases. There were 2 (16,6%) fatal cases due to sepsis and multi-organ failure development. CONCLUSIONS: Children with complete tracheal rings are very complicated patients with various comorbidities. Despite the advances in medicine, sometimes it is impossible to save lives of these children. The use of extracorporeal circulation (ECMO and bypass) allows us to safely perform reconstructive surgery on the trachea and save the child from respiratory failure manifestations. If needed, simultaneous correction of heart and tracheal defects is possible. Slide tracheoplasty allows to increase trachea lumen at least in 1.5-2 times. Mechanical ventilation is an unfavorable predictive factor for the outcomes of congenital tracheal stenosis management. LEVEL OF EVIDENCE: III.

Straightforward approach to produce recombinant scorpion toxins-Pore blockers of potassium channels.

Scorpion venom peptide blockers (KTx) of potassium channels are a valuable tool for structure-functional studies and prospective candidates for medical applications. Low yields of recombinant KTx hamper their wide application. We developed convenient and efficient bioengineering approach to a large-scale KTx production that meets increasing demands for such peptides. Maltose-binding protein was used as a carrier for cytoplasmic expression of folded disulfide-rich KTx in E. coli. TEV protease was applied for in vitro cleavage of the target peptide from the carrier. To produce KTx with retained native N-terminal sequence, the last residue of TEV protease cleavage site (CSTEV) was occupied by the native N-terminal residue of a target peptide. It was shown that decreased efficiency of hydrolysis of fusion proteins with non-canonical CSTEV can be overcome without by-product formation. Disulfide formation and folding of a target peptide occurred in cytoplasm eliminating the need for renaturation procedure in vitro. Advantages of this approach were demonstrated by producing six peptides with three disulfide bonds related to four KTx sub-families and achieving peptide yields of 12-22mg per liter of culture. The developed approach can be of general use for low-cost production of various KTx, as well as other disulfide-rich peptides and proteins.

Label-free aptasensor for thrombin determination based on the nanostructured phenazine mediator.

New aptasensors based on DNA aptamer and polycarboxylated thiacalix[4]arenes in cone, 1,3-alternate and partial cone configurations bearing Neutral Red (NR) at substituents at the lower rim have been developed and applied for thrombin detection. The assembly of the biorecognition layer was optimized by AFM and EIS study to reach the maximal coverage and regular composition of the surface layer. The interaction of the NR groups with thrombin suppressed the electron hopping between oxidized and reduced mediator groups. This regularly decreased the NR peak current and increased the resistance of the charge transfer. The aptasensor makes it possible to detect from 1 nM to 1 µM of thrombin with the detection limit of 0.05-0.5 nM. No effect of the 1000 excess of bovine serum albumin on the signal was observed. The influence of thiacalix[4]arene configuration on the sensitivity of aptasensor signal toward thrombin is discussed.