Catheter Exchange With Elongation of Tunnel (CEET) Procedure-A Novel Technique for Cuff Extrusion of Tunneled Dialysis Catheter: Surgical Experience and Early Outcomes.

Background: Cuff extrusion of tunneled dialysis catheter (TDC) leads to catheter dysfunction, leading to loss of vascular access and the need for new catheter. Definitive management is to remove TDC and reinsert new catheter by new venous puncture and tunnel, which may not be possible in all cases. The study evaluated the surgical experience and early outcomes of a novel "Catheter Exchange with Elongation of Tunnel (CEET)" procedure for cuff extrusion.

Conformations of cyclic octapeptides. 4. Diastereomers of cyclo(Gly-Pro-Phe-Ala-Asn-Ala-Val-Ser).

Stereoisomers of cyclo(Gly-Pro-Phe-Ala-Asn-Ala-Val-Ser) were synthesized. NMR studies of their solution conformations, focusing on peptide N-H solvent exposure, were made. These indicated that a single proline residue in the cyclic octapeptide ring is insufficient constraint to stabilize the backbone conformations that were previously established for cyclo(Gly-Pro-Phe-Ala)2.

Conformation of antibiotic X-537A (lasalocid-A) and its calcium complex in acetonitrile solvent using circular dichroism spectroscopy.

The calcium binding characteristics of antibiotic X-537A (lasalocid-A) in a lipophilic solvent, acetonitrile (CH3CN), have been studied using circular dichroism (CD) spectroscopy. The analysis of the data indicated that in this medium polar solvent, X-537A forms predominantly the charged complexes of stoichiometries 2:1 and 1:1, the relative amounts of the two being dependent on [Ca2+]. The conformations of the complexes, arrived at on the basis of the data, seem to indicate a rigid part encompassing Ca2+, liganded to 3 oxygens of the molecule, viz.

Circular dichroism and nuclear magnetic resonance studies on the complexation of valinomycin with calcium.

Complexation of valinomycin (VM) with the divalent cation Ca2+ in a lipophilic solvent, acetonitrile (CH3-CN), has been studied by using circular dichroism and proton and carbon-13 nuclear magnetic resonance (1H NMR and 13C NMR). From analyses of the spectral data, it is concluded that VM forms a 2:1 (peptide-ion-peptide) sandwich complex with Ca2+, at low concentration of VM. At moderate concentrations of the salt, in addition to the sandwich complex, an equimolar (1:1) complex different from those observed for potassium and sodium is also observed.

Hydrogen-1 and carbon-13 magnetic resonance studies of nonactin-calcium complex.

For an understanding of the cation selectivity and general binding characteristics of macrotetralide antibiotic nonactin (NA) with ions of different sizes and charges, the nature of binding of divalent caption, Ca2+, to NA and conformation of the NA-Ca2+ complex have been studied by use of 270-MHz proton nuclear magnetic resonance (1H NMR) and carbon-13 nuclear magnetic resonance (13C NMR). The calcium ion induced significantly large changes in chemical shifts for H7, H2, H3, and H5 protons of NA and relatively small changes for H18 and H21 protons. Changes in 13C chemical shift were quite large for carbonyl carbon, C1; it is noteworthy that in the NA-K+ complex, H2 and H21 protons practically do not shown any change during complexation and carbonyl carbon shows a much smaller chemical shift change.