Experimental surgery as part of the development of degradable biomaterials for cardiovascular surgery

Introduction: Cardiovascular diseases are responsible for significant morbidity and mortality in the population. Artificial vascular grafts are often essential for surgical procedures in radical or palliative treatment. Many new biodegradable materials are currently under development. Preclinical testing of each new material is imperative, both in vitro and in vivo, and therefore animal experiments are still a necessary part of the testing process before any clinical use. The aim of this paper is to present the options of using various experimental animal models in the field of cardiovascular surgery including their extrapolation to clinical medicine. Methods: The authors present their general experience in the field of experimental surgery. They discuss the selection process of an optimal experimental animal model to test foreign materials for cardiovascular surgery and of an optimal region for implantation. Results: The authors present rat, rabbit and porcine models as optimal experimental animals for material hemocompatibility and degradability testing. Intraperitoneal implantation in the rat is a simple and feasible procedure, as well as aortic banding in the rabbit or pig. The carotid arteries can also be used, as well. Porcine pulmonary artery banding is slightly more difficult with potential complications. The banded vessels, explanted after a defined time period, are suitable for further mechanical testing using biomechanical analyses, for example, the inflation-extension test. Conclusion: An in vivo experiment cannot be avoided in the last phases of preclinical research of new materials. However, we try to strictly observe the 3R concept ­ Replacement, Reduction and Refinement; in line with this concept, the potential of each animal should be used as much as possible to reduce the number of animals.

Sternotomy in thyroid surgery

Introduction: A bulky retrosternal goiter means for the surgeon to consider an extracervical approach, usually from a partial sternotomy. Methods: Retrospective evaluation of a group of thyroid operations requiring sternotomy in a ten-year period (year 2012­2021), in an attempt to predict the need for sternotomy. Results: We performed a total of 1254 thyroid operations, with partial sternotomy required in 11 cases (0.88%): in 6 women and 5 men aged 43­84 years (mean 73.1 years). For these, 3 total thyroidectomies and 6 hemithyroidectomies (lobectomies) were performed. In 2 cases, we operated on the mediastinal residue, or regenerate, after a previous thyroidectomy from the cervical approach. The duration of hospitalization was 5­14 days, once there was bleeding with the need for operative revision, otherwise the procedures were without complications, including phonation. The border of the lower part of the thyroid gland in relation to the upper border of the aortic arch was in the range of +20 to -22 mm. The mean was -8.5 mm. Conclusion: All sternotomy thyroidectomies performed by us had a close relationship to, or overlapped with the upper line of the aortic arch. Significantly retrosternal propagating goiters are mostly eufunctional (81.9 % in our group) and develop in patients in the seventh or eighth decade of life. Therefore, if only one lobe propagates intrathoracically, a hemithyroidectomy is sufficient. A carcinoma is rarely present; in one case in our group. We believe that the necessity of sternotomy cannot be accurately predicted, but it is necessary to be prepared for it, especially in the case of a goiter exceeding the level of the aortic arch. In case of greater retrosternal propagation, it is certainly appropriate to perform a CT, for surgical reasons (possibility of sternotomy, risk of leaving part of the gland) and anesthetic reasons (compression and deviation of the trachea).

Transport of 4-deoxy- and 6-deoxy-D-glucose in baker's yeast.

Tritium-labelled 4-deoxy-D-glucose (4-dglc) and 6-deoxy-D-glucose (6-dgcl) were prepared by catalytic hydrogenolysis of the corresponding deoxyiodo derivatives with gaseous tritium. The two sugars are transported into Saccharomyces cerevisiae by both the constitutive glucose and the inducible galactose carrier. Uranyl ions are powerful inhibitors. The pH optimum in uninduced cells lies at 5.5 for both sugars, the apparent activation energies (between 15 and 35 degrees C) are 25.1 kJ/mol and 16.5 kJ/mol, respectively. The steady-state intracellular concentration of both sugars is less than the extracellular one (no uphill transport). Neither of them is a substrate of yeast hexokinase. 4-Deoxy-D-glucose undergoes a dinitrophenol-sensitive conversion to an unknown metabolite which is not phosphorylated and may represent one of its oxidation products.