RESUMO
Fullerenes violating the isolated pentagon rule (IPR) are only obtained in the form of their derivatives. Since the [5,5]-bond carbons are highly reactive, they are easily attacked by reagents to release the bond strains. Non-IPR endohedral metallofullerenes, however, still have unsaturated sp (2) carbons at the [5,5] bond junctions, which allow their chemical properties to be probed. In this work, La 2@C 72 was chosen as a representative non-IPR metallofullerene, since it has been experimentally proposed to have either the #10611 or #10958 non-IPR cage structure ( J. Am. Chem. Soc. 2003, 125, 7782 ), while theoretical calculations have suggested that the #10611 cage is more stable ( J. Phys. Chem. A 2006, 110, 2231 ). La 2@C 72 was modified by photolytic reaction with the carbene reagent 2-adamantane-2,3-[3H]-diazirine. Six isomers of adamantylidene monoadducts were isolated and characterized using various kinds of measurements, including high-performance liquid chromatography, matrix-assisted laser desorption ionization mass spectrometry, UV-vis-near-infrared spectroscopy, cyclic voltammetry, differential-pulse voltammetry, (13)C NMR spectroscopy, and single-crystal X-ray diffraction. Electronic spectra and electrochemical studies revealed that the essential electronic structures of La 2@C 72 are retained in the six isomers and the adamantylidene group acts as a weak electron-donating group toward La 2@C 72. X-ray structural results unambiguously elucidated that La 2@C 72 has the #10611 chiral cage (i.e., D 2 symmetry) with two pairs of fused pentagons at each pole of the cage and that the two La atoms reside close to the two fused-pentagon pairs. On the basis of these results and theoretical calculations, it is concluded that the fused-pentagon sites are very reactive toward carbene but that the carbons forming the [5,5] junctions are less reactive than the adjacent ones; this confirms that these carbons interact strongly with the encaged metals and thus are stabilized by them.
RESUMO
STUDY DESIGN: A 9-year-old boy with severe myelomeningocele kyphosis was treated by kyphectomy using a surgical threadwire. OBJECTIVE: To describe a new method of kyphectomy for severe kyphotic deformity in a child with myelomeningocele using a surgical threadwire. SUMMARY OF BACKGROUND DATA: Although several methods of kyphectomy for severe kyphotic deformity in children with myelomeningocele have been reported, few of these methods allow preservation of the nonfunctioning dural sac and cerebrospinal fluid flow, with the aim of reducing complications. METHODS: The preoperative kyphotic angle was 113 degrees. There was repeated skin ulceration over the apex of the kyphos. Kyphectomy at the Th12 to L3 vertebral levels was performed using a surgical threadwire (T-saw, developed by Tomita and colleagues in 1996), preserving the entire dural sac. RESULTS: The T-saw allowed anterior dissection of the dural sac over the length of the planned resection, thus preserving cerebrospinal fluid flow throughout the entire subarachnoid space. The kyphotic angle was decreased to 10 degrees after the operation, and the postoperative clinical course was uneventful. At the 2-year follow-up assessment, the kyphotic angle was 10 degrees according to plain radiograph. At this writing, the boy is able to maintain a sitting position without any difficulty. CONCLUSIONS: For this child with myelomeningocele, kyphectomy using a surgical threadwire (T-saw) provided a satisfactory result without any major complication.