RESUMO
New reagents have been sought for directed ortho cupration in which the use of cyanide reagents is eliminated. CuOCN reacts with excess TMPLi (TMP = 2,2,6,6-tetramethylpiperidide) in the presence of limited donor solvent to give crystals that are best represented as (TMP)2Cu0.1Li0.9(OCN)Li2(THF) 8, whereby both Lipshutz-type lithiocuprate (TMP)2Cu(OCN)Li2(THF) 8a and trinuclear (TMP)2(OCN)Li3(THF) 8b are expressed. Treatment of a hydrocarbon solution of TMP2CuLi 9a with LiOCN and THF gives pure 8a. Meanwhile, formation of 8b is systematized by reacting (TMPH2)OCN 10 with TMPH and nBuLi to give (TMP)2(OCN)Li3(THF)211. Important to the attribution of lower/higher order bonding in lithiocuprate chemistry is the observation that in crystalline 8, amide-bridging Cu and Li demonstrate clear preferences for di- and tricoordination, respectively. A large excess of Lewis base gives an 8-membered metallacycle that retains metal disorder and analyses as (TMP)2Cu1.35Li0.659 in the solid state. NMR spectroscopy identifies 9 as a mixture of (TMP)2CuLi 9a and other copper-rich species. Crystals from which the structure of 8 was obtained dissolve to yield evidence for 8b coexisting in solution with in situ-generated 9a, 11 and a kinetic variant on 9a ( i-9a), that is best viewed as an agglomerate of TMPLi and TMPCu. Moving to the use of DALi (DA = diisopropylamide), (DA)2Cu0.09Li0.91(Br)Li2(TMEDA)212 (TMEDA = N,N,N',N'-tetremethylethylenediamine) is isolated, wherein (DA)2Cu(Br)Li2(TMEDA)212a exhibits lower-order Cu coordination. The preparation of (DA)2Li(Br)Li2(TMEDA)212b was systematized using (DAH2)Br, DAH and nBuLi. Lastly, metal disorder is avoided in the 2 : 1 lithium amide : Lipshutz-type monomer adduct (DA)4Cu(OCN)Li4(TMEDA)213.
RESUMO
BACKGROUND: Although gastrostomy tube insertion - whether endoscopic or open - is generally safe, procedure-related complications have been reported. OBJECTIVE: To compare gastrostomy tube insertion-related complications between percutaneous endoscopic gastrostomy and open gastrostomy at a single pediatric centre. METHODS: The charts of children (younger than 17 years of age at the time of tube insertion) who underwent endoscopic or open gastrostomy tube insertion from January 2005 to December 2007 at the Stollery Children's Hospital (Edmonton, Alberta) were examined. RESULTS: A total of 298 children underwent gastrostomy tube insertion over a period of three years. After excluding patients with incomplete charts, 160 children (91 boys, mean [± SD] age 3.18 ± 4.73 years) were included. Eighty-five children (mean age 4.50 ± 5.40 years) had their gastrostomy tube inserted endoscopically, while the remaining 75 (mean age 1.68 ± 3.27 years; P<0.001) underwent an open procedure. The overall rate of major complications was 10.2% for the endoscopic technique and 8.6% for the open technique (P=0.1). Major infections were higher in the endoscopic technique group, while persistent gastrocutaneous fistulas after tube removal were more common in the open technique group. CONCLUSION: Although the rate of major complications was similar between the endoscopic and open tube insertion groups, major infections were more common among children who underwent endoscopic gastrostomy. The decision for gastrostomy tube insertion was primarily based on clinical background.