Structural chemistry of polycyclic heteroaromatic compounds. Part 13. Photoelectron spectra and electronic structures of tricyclic hetarenes of the anthracene type.

The ultraviolet photoelectron spectra of two tricyclic heteroaromatic compounds (2,3) that are pi-isoelectronic with anthracene (1) have been recorded and analysed making use of semi-empirical AM1 and PM3, as well as density functional theory (DFT) B3LYP calculations. In compounds 2 and 3, one peripheral benzene ring of compound 1 is substituted by a thiophene ring that is either [b]- or [c]-annellated. In compounds 2 and 3, only small shifts are found for most of the ionization potentials of pi electrons. Since the ionization energies of all occupied pi molecular orbitals of compounds 1-3 could be assigned, a direct comparison of their pi electron energy is possible. Compared with compound 1, the pi-electron system of naphtho[2,3-b]thiophene (2) is stabilized by 0.6 eV, while that of naphtho[2,3-c]thiophene (3) is destabilized by 0.2 eV. [b]-Annellation of the thiophene ring is thus favourable while [c]-annellation is unfavourable.

Ascites drainage leading to intestinal adhesions at the mesentery of the small intestine with fatal outcome.

A common problem in patients with chronic liver diseases and liver cirrhosis is the development of ascites. First line therapy for ascites is the restriction of sodium intake and a diuretic treatment. Paracentesis is indicated in patients with large compromising volumes of ascites. In selected cases, permanent drainage of ascites over prolonged periods of time may be indicated. In the case presented here, a 66-year-old male patient, who was hospitalized with liver cirrhosis caused by alcoholic abuse, required permanent drainage of ascites. After three weeks of continuous ascites drainage, he developed bacterial peritonitis. Conventional attempts to remove the catheter by transcutaneous pulling failed and we thus decided to perform a median laparotomy to remove the catheter surgically. Intraoperatively an adhesion of the ascites drain (a so called 'basket catheter') to the mesentery very close to the small intestine was found, approximately 50 mm distal of the ligament suspensorium duodeni (ligament of Treitz). The basket catheter used for this patient was especially designed to drain infections, not fluids. We solved the adhesion, removed the basket catheter, placed a new surgical drain and finished the operation. The patient developed a rupture of his abdominal fascia suture 12 days later, which was caused by massive ascites and complicated by hepatorenal syndrome type I. The patient was taken to the operating theater again. After the second operation, the chronic liver failure decompensated and the patient died. Ascites caused by liver cirrhosis is still a medical challenge. The indication for the use of the correct percutaneous catheter for permanent paracentesis should be carefully considered. Some catheters are obviously not suited to drain ascites and may lead to fatal outcomes.

Protein sequencing experiment planning using analogy.

Experiment design and execution is a central activity in the natural sciences. The SeqER system provides a general architecture for the integration of automated planning techniques with a variety of domain knowledge in order to plan scientific experiments. These planning techniques include rule-based methods and, especially, the use of derivational analogy. Derivational analogy allows planning experience, captured as cases, to be reused. Analogy also allows the system to function in the absence of strong domain knowledge. Cases are efficiently and flexibly retrieved from a large casebase using massively parallel methods. The SeqER system is initially configured to plan protein sequencing experiments. Planning is interleaved with experiment execution, simulated using the SequenceIt program. SeqER interacts with a human user who analyzes the data generated by laboratory procedures and supplies SeqER with new hypotheses. SeqER is a vehicle in which to test theories about how scientists reason about experimental design.