Javier Santamaría

STRUCTURAL EXAMINATION OF SUPRAMOLECULAR ARCHITECTURES BY ELECTROSPRAY IONIZATION MASS SPECTROMETRY

Reversibly self-assembling host–guest complexes of the softball type are characterized by electrospray ionization mass spectrometry. Quaternary ammonium ions serve simultaneously as guests and ion labels. Isotope pattern analysis, inclusion of labeled guests, heterodimer experiments, size and shape dependence, and collision-induced fragmentation reveal that the capsular structure of these hydrogen-bonded complexes is retained in the gas phase with the guests inside their cavity. The results parallel findings from solution-phase NMR experiments and show that the guests are encapsulated inside the cavity. These results also demonstrate the value of mass spectrometry for high-order structural examination of supramolecular architecture.

Effectiveness of retinoic acid treatment for redifferentiation of thyroid cancer in relation to recovery of radioiodine uptake

Background: Retinoic acid (RA) treatment has been used for redifferentiation of metastatic thyroid neoplasia that have lost radioiodine (131I) uptake with heterogeneous results. Aim: Retrospective analysis of the recovery rate of 1311 uptake after RA treatment in patients from 11 Spanish hospitals. Methods: Twenty-seven patients (14 men, 13 women) with papillary [21], follicular [4], and oncocytic [2] thyroid cancer initially treated with total thyroidectomy plus 131I, and with 131I negative metastatic disease, were given 13-cis RA (0.66–1.5 mg/kg for 5–12 weeks) followed by a therapeutic 131I dose (3700–7400 MBq); 3 months later thyroglobulin levels and computed tomography imaging were performed. Results: In 9 out 27 cases (33%) (8 papillary, 1 follicular) optimal positive 131I scan was observed after RA treatment; in the remaining 18, 10 had a suboptimal uptake (7 papillary, 2 follicular, 1 oncocytic) and in the rest there was no 131I uptake recovery (6 papillary, 1 follicular, 1 oncocytic). In 17 positive responses to RA (either optimal or suboptimal) in which image follow-up was available, decrease or stabilization of metastatic growth was observed in 7, while tumor mass increased at short term in the remaining 10. No major side effects were detected. Conclusion: Quite a high rate of 131I uptake recovery after RA treatment may be obtained in advanced differentiated thyroid cancer, but the potential modification of the natural course of the disease is uncertain. A better biological characterization of these tumors allowing the identification of potential responders to RA may improve the outcome of RA coadjuvant therapy.

Regioselective Synthesis of 4,6,7-Trisubstituted Benzofurans from Furfural Imines and Nonheteroatom Stabilized Alkynylcarbene Complexes

Nonheteroatom stabilized chromium alkynylcarbene complexes 3,6, generated in situ from Fischer cabene complexes 1, smoothly react with furan-2-ylmethanimines 4 to provide substituted 7-aminobenzofurans 5 in moderate to good yields. The procedure involves the construction of the arene ring by a regioselective [3+3] carbocyclization reaction.