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Jones Michael,Moran Brendan,Heald Richard John,Bunni John 대한대장항문학회 2024 Annals of Coloproctolgy Vol.40 No.1
Anastomotic and rectal stump leaks are feared complications of colorectal surgery. Diverting stomas are commonly used to protect low rectal anastomoses but can have adverse effects. Studies have reported favorable outcomes for transanal drainage devices instead of diverting stomas. We describe our use of the Heald anal stent and its potential impact in reducing anastomotic or rectal stump leak after elective or emergency colorectal surgery. We performed a single-center retrospective analysis of patients in whom a Heald anal stent had been used to “protect” a colorectal anastomosis or a rectal stump, in an elective or emergency context, for benign and malignant pathology. Intraoperative and postoperative outcomes were reviewed using clinical and radiological records. The Heald anal stent was used in 93 patients over 4 years. Forty-six cases (49%) had a colorectal anastomosis, and 47 (51%) had an end stoma with a rectal stump. No anastomotic or rectal stump leaks were recorded. We recommend the Heald anal stent as a simple and affordable adjunct that may decrease anastomotic and rectal stump leak by reducing intraluminal pressure through drainage of fluid and gas.
Reduction of pertechnetate [Tc(VII)] by aqueous Fe(II) and the nature of solid phase redox products
Zachara, John M.,Heald, Steve M.,Jeon, Byong-Hun,Kukkadapu, Ravi K.,Liu, Chongxuan,McKinley, James P.,Dohnalkova, Alice C.,Moore, Dean A. Elsevier 2007 Geochimica et cosmochimica acta Vol.71 No.9
<P><B>Abstract</B></P><P>The subsurface behaviour of <SUP>99</SUP>Tc, a contaminant resulting from nuclear fuels reprocessing, is dependent on its valence (e.g., IV or VII). Abiotic reduction of soluble Tc(VII) by Fe(II)<SUB>(aq)</SUB> in pH 6–8 solutions was investigated under strictly anoxic conditions using an oxygen trap (<7.5×10<SUP>−9</SUP>atmO<SUB>2</SUB>). The reduction kinetics were strongly pH dependent. Complete and rapid reduction of Tc(VII) to a precipitated Fe/Tc(IV) form was observed when 11μmol/L of Tc(VII) was reacted with 0.4mmol/L Fe(II) at pH 7.0 and 8.0, while no significant reduction was observed over 1 month at pH 6.0. Experiments conducted at pH 7.0 with Fe(II)<SUB>(aq)</SUB>=0.05–0.8mmol/L further revealed that Tc(VII) reduction was a combination of homogeneous and heterogeneous reaction. Heterogeneous reduction predominated after approximately 0.01mmol/L of Fe(II) was oxidized. The heterogeneous reaction was more rapid, and was catalyzed by Fe(II) that adsorbed to the Fe/Tc(IV) redox product. Wet chemical and Fe–X-ray absorption near edge spectroscopy measurements (XANES) showed that Fe(II) and Fe(III) were present in the Fe/Tc(IV) redox products after reaction termination. <SUP>57</SUP>Fe-Mössbauer, extended X-ray adsorption fine structure (EXAFS), and transmission electron microscopy (TEM) measurements revealed that the Fe/Tc(IV) solid phase was poorly ordered and dominated by Fe(II)-containing ferrihydrite with minor magnetite. Tc(IV) exhibited homogeneous spatial distribution within the precipitates. According to Tc-EXAFS measurements and structural modeling, its molecular environment was consistent with an octahedral Tc(IV) dimer bound in bidentate edge-sharing mode to octahedral Fe(III) associated with surface or vacancy sites in ferrihydrite. The precipitate maintained Tc(IV)<SUB>aq</SUB> concentrations that were slightly below those in equilibrium with amorphous Tc(IV)O<SUB>2</SUB>·<I>n</I>H<SUB>2</SUB>O<SUB>(s)</SUB>. The oxidation rate of sorbed Tc(IV) in the Fe/Tc precipitate was considerably slower than Tc(IV)O<SUB>2</SUB>·<I>n</I>H<SUB>2</SUB>O<SUB>(s)</SUB> as a result of its intraparticle/intragrain residence. Precipitates of this nature may form in anoxic sediments or groundwaters, and the intraparticle residence of sorbed/precipitated Tc(IV) may limit <SUP>99</SUP>Tc remobilization upon the return of oxidizing conditions.</P>