Understanding conductivity in molecular switches: a real space approach in octaphyrins

In recent years, expanded porphyrins have emerged as a promising class of π-conjugated switches whose conductance is studied from the electron density.

Understanding the molecular switching properties of octaphyrins

Triggering Hückel–Möbius topological and aromaticity switches in octaphyrins by protonation and redox reactions.

[Early and late complications after implantation of central venous catheters]

The use of implantable central venous catheters by the puncture-technique of Nagy is a safe method performed by trained surgeons. Due to the high mobility and then reduction of painful blood samples this method contributes favourably to the improvement of the quality of life of children with chronic diseases. The analysis of 140 catheters implanted in the Department of Pediatric Surgery of the University of Leipzig between 1995 and 2000 showed 11 cases with early complications. As the most frequent late complications were infection and thrombosis in 51 children. Neutropenia is a particular risk factor during polychemotherapy of malignant tumors. Staphylococcus epidermidis was the most frequently isolated bacillus. Catheter associated infections are only partly treatable by antibiotic therapy. In 29 of 44 cases the explantation of the catheter was necessary. Only a strict hygienic regimen would minimize the risk of infection

Comparison of haemostatic parameters in arterial and venous blood from patients with peripheral arterial occlusive disease

BACKGROUND

Several studies proved the co-existence of peripheral arterial occlusive disease (PAOD) and hypercoagulability. However, in practice coagulation parameters are mainly determined from venous blood samples. In this study several coagulation parameters in arterial and venous blood were examined for differences and the validity of coagulation parameters determined in venous blood was investigated.

PATIENTS AND METHODS

In 22 patients with peripheral artery disease venous and arterial blood samples from vessels of the diseased leg were examined for the concentration of thrombine-antithrombine III-complex (TAT), prothrombin fragments (F1 and F2) and D-dimers, and results were compared.

RESULTS

Mean concentrations of TATs and prothrombin fragments F1 and F2 were significantly higher in arterial than in venous blood. TAT-complex was the most sensitive parameter for quantification of thrombin generation. D-dimer levels did not differ in arterial and venous blood. TAT and F1 and F2 concentrations in arterial and venous blood did not correlate in individual patients whereas D-dimer concentration did.

CONCLUSION

The determination of TAT and F1 + F2 in venous blood does not adequately reflect the degree of the local coagulation activation in the arterial system. As indicators for hypercoagulability, D-Dimer values are less sensitive than F1 + 2, but venous D-dimer concentrations mirror arterial levels.