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B Wilhelm

Publications and source records attributed to B Wilhelm.

8 recordsLinked to original sources
PubMed1978

Effect of tetramethylammonium ions on conformational changes of DNA in the premelting temperature range.

The reversible conformational change of DNAs and polydeoxyribonucleotides occurring before melting was followed by circular dichroism. deltatheta/deltaT, the rate of change of ellipticity theta with temperature, was used mainly as a measure of this premelting phenomenon. If sodium ions were replaced by tetramethylammonium ions deltatheta/deltaT decreased for poly (dA) poly (dT) and poly (dA.dT) poly (dT.dA), but increased for poly (dG.dC) poly (dC.dG). DNAs of different base composition showed no more premelting (deltatheta/deltaT approximately 0) even at low molarities of TMACl provided the Na/TMA ratio was very small. For all cases studied the theta values at 0 degrees C and at a given ionic strength were smaller in NaCl than in TMACl. When studying the series of ammonium ions from NH4+ to (C2H5)4N+, the deltatheta/deltaT values first decreased, going through zero with TMA+ ions, and then increased again. A tentative and qualitative explanation of our results can be given: (a) Hydration of the polymers increases in presence of TMA ions and their average stability decreases; locally, however, (AT) pairs are preferentially stabilized by TMA ions owing to a specific interaction at the level of O2 of thymine. (b) In order to explain the different behaviour of (AT) polymers and DNA, it is assumed that only the B structure is able to accommodate TMA ions in the small groove of the double stranded helix.

Chemical Phenomena↗
PubMed1977

[Pancreatic injuries].

Within a constant increase in the number of injured in the last ten years a significant rise in the number of abdominal injuries has been noticeable. From 1,2% of ten years ago, abdomeninal injuries have risen to 4,6% of the total number of treated patients. While in earlier years pancreatic injuries were a rarity, in 1974 there were six patients with an injury to the pancreas due to either a blunt or penetranting wound of the abdomen. Out of altogether (21) treated patients only in one was an isolated injury to the pancreas found. We have never been able to recognise with certainty the injury to the pancreas with clinical methods, but only surgical exploration enabled us to make an accurate diagnosis. In all surgically treated pancreatic injuries a suture of the capsule of the pancreas was done after débridement and minute hemostasis. Only in one case of complete transversal rupture of the corpus we decided upon a resection and a blind closure of the truncus. The site of the injury was obligatorily repeatedly drained in order to remove pancreatic secretions from the abdominal cavity. Out of the total number of patients surgically operated were 12, of whom 7 died. Other patients could not be operated upon because of the traumatic shock, so that pancreatic traumas in these patients were discovered at a postmortem examination.

Abdominal Injuries↗