Is the parallel or antiparallel beta-sheet more stable? A semiempirical study.

The geometry and energy of parallel and antiparallel peptidic beta-sheets have been calculated using AM1. beta-Sheets composed of two peptide chains of up to 11 amino acid residues (Ala and Gly) and the dimers of cyclooctapeptides are used as model systems. The enthalpic difference between the parallel and the antiparallel arrangement is calculated to be very small, as it is found experimentally for the cyclic systems. The coordinates of the calculated structure of the cyclooctapeptide dimer 1 (cyclo-D,L-(Ala)8) have an rms deviation of only 0.223 A to the coordinates of the corresponding cyclopeptide obtained by X-ray analysis.

[Laparoscopic colon reposition and closure of the diaphragm in secondary incarcerated pre-existent diaphragmatic hernia]. / Laparoskopische Colonreposition und Zwerchfellverschluss bei sekundär incarcerierter vorbestehender Zwerchfellhernie.

We report on a 28-year-old patient, who acquired a left diaphragmatic hernia after suffering a motorcycle accident seven years ago. The diaphragmatic hernia was not diagnosed at that time. After a laparoscopic cholecystectomy performed for acute cholcystitis, there was herniation and secondary incarceration of a bowel segment into the preexistent diaphragmatic hernia. We describe laparoscopic surgical repositioning of the bowel segment and closure of the diaphragmatic defect.

[Laparoscopic excision of a urachus umbilical fistula]. / Laparoskopische Excision einer Urachusnabelfistel.

We report on a 24-year-old female patient with a chronic secretion from an umbilical fistula. We describe the laparoscopic removal of the fistula using two 5-mm and two 10-mm ports.

[Laparoscopic endoscopic pre-peritoneal combined hernia operation in incarcerated indirect inguinal hernia]. / Laparoskopisch endoskopisch-präperitoneale kombinierte Hernien-Operation bei incarcerierter indirekter Inguinalhernie.

We report on a 73-year-old patient with an incarcerated right sided groin hernia. First the incarcerated small bowel was gently retracted laparoscopically; then using the extraperitoneal endoscopic approach the hernial sack was redused and a 15/13 cm prosthesis (polypropylene mesh) brought in appropriate position and fixed with endo-staples. Prior to closing the trocar-incisions the vitality of the small bowel was checked once again laparoscopically.

Analysis of the lipoteichoic-acid-like macroamphiphile from Bifidobacterium bifidum subspecies pennsylvanicum by one- and two-dimensional 1H- and 13C-NMR spectroscopy.

The native lipoteichoic-acid-like amphiphile from Bifidobacterium bifidum subspecies pennsylvanicum and its basic glycan moiety, obtained by alkaline hydrolysis, were studied by 1H-, 13C-, and 31P-NMR, DEPT (distorsionless enhancement by polarization transfer), 1H-1H correlation spectroscopy and 13C-1H shift correlation NMR spectroscopy. The results are consistent with the structure elucidated by chemical analysis (Fischer, W., preceding paper in this journal): (formula; see text) and establish the structures of the repeating units independently. In addition to characteristic shifts in the 13C-NMR spectrum, the sites of phosphodiester and alanine ester bonds are also manifest in the 1H-NMR spectrum. Substitution of the glycerophosphate residues can be recognized in the 31P-NMR spectrum also.

[Hydrothorax as a complication due to left internal jugular vein catheterisation (author's transl)]. / Infusionsthorax nach V. jugularis-interna-Katheterisation.

We present a case of hydrothorax, which occured in a young man following unrecognized vein perforation by a left internal jugular vein catheter two days after cannulation. The mechanism of this complication and methods for its prevention are discussed.