Tracheal necrosis following thyroid radiofrequency ablation.

INTRODUCTION: Radiofrequency ablation for benign thyroid nodules has a low rate of complications in experienced hands for selected indications, but tracheal necrosis is a major complication. CASE REPORT: A 60 year-old female patient underwent percutaneous radiofrequency ablation of an unesthetic benign isthmic thyroid nodule. The procedure was performed with a cooled electrode, using the "moving shot" technique on a trans-isthmic approach, under general anesthesia. Postoperative course was complicated by dysphonia and cervical pain implicating a third-degree skin burn of the medial cervical region progressing to severe soft-tissue and cervical tracheal necrosis. DISCUSSION: Risk factors in the present case included the general anesthesia, isthmic location and thyroid nodule volume. To avoid this kind of complication, the procedure should be performed under local anesthesia, using cooled dextrose solution hydrodissection between trachea, thyroid and skin. Ahead of radiofrequency ablation, patients should be informed of possible major complications, especially if the indication is cosmetic.

Molecular modeling and inhibition of phospholipase A2 by polyhydroxy phenolic compounds.

Phospholipases A(2) are enzymes responsible for the hydrolysis of membrane phospholipids that release arachidonic acid, which serves as substrate for pro-inflammatory mediators, such as prostaglandins and leucotriens. The design of specific inhibitors for PLA(2) might help in the development of new anti-inflammatory drugs. Polyhydroxy phenolic compounds, such as flavonoids, vitamin E, rosmarinic acid and aristolochic acid, are able to inhibit PLA(2) from different sources. Herein, we have studied the kinetic behavior and the capacity of inhibiting edema formation induced by PLA(2) of five different polyhydroxy phenolic compounds (two phenolic derivatives and three acetophenone hydroxylated derivatives) extracted from the venom of Crotalus adamanteus. The results showed that compounds 1,3-dihydroxy benzene, 1,3,5-trihydroxy benzene and 2,4,6-trihydroxy acetophenone were the most efficient in the inhibition of the enzymatic activity and edema induction by PLA(2). It was also verified that the number of hydroxyls in each molecule is not a limiting factor for the inhibition capacity of these compounds. Molecular modeling studies indicated that the most active compounds are linked to the amino acid Asp 49 and that they destabilize the coordination of the calcium atom, which is essential to the catalytic activity. The study of potential surfaces showed that there are conditions in which the potential values must be adequate for enzyme complex formation with polyhydroxy phenolic compounds. When the potential over the hydroxyl surfaces is very high, formation of stable complexes does not occur and the enzyme does not act intensely. These results might be helpful in the design of a drug that specifically inhibits PLA(2).