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Biomedical subjects

W Beck

Publications and source records attributed to W Beck.

193 records · Page 11Linked to original sources
PubMedDate not supplied

Application of a diode-array detector in capillary electrophoresis.

In the last decade diode-array detection has proved to be extremely useful in high performance liquid chromatography in recording UV-visible spectra directly and on-line in the column effluent. In capillary electrophoresis (CE) only fast-scanning detectors with long scan times (up to 2 s) are commercially available. A home-made CE instrument with a diode-array detector (DAD) was built and compared with a commercial fast-scanning detector. It is shown that the fast-scanning detector is advantageous when less than eight wavelengths are monitored. Due to the high data collection rate the DAD is superior if high resolution UV-visible spectra are acquired or if several spectra of a narrow peak (usual peak width in CE below 5 s) are needed for peak purity control. It is shown that DAD detection can help to develop separation methods, to identify peaks according to their UV-visible spectra, and to check peak purity.

Ascorbic Acid↗
PubMedDate not supplied

[Effect of a local surgical procedure on the incidence of metastases following neoadjuvant chemotherapy of osteosarcoma].

Following preoperative chemotherapy of 9-18 weeks duration limb salvage procedures were performed instead of ablative surgery in about 1/2 of the patients (pts). Overall continuous disease-free survival rate is 69% (80/115) at 37 (21-51) months. 5 pts died from therapy related complications, 4 developed a local failure (2 following amputation and 2 following limb salvage each) and 26 pts developed pulmonary metastases. The incidence of pulmonary metastases after en bloc resection, but not after shank rotation plasty, was found to be significantly increased over that after ablative surgery (83% vs 60% metastases free survival (MFS) at 40 months, p less than 0.05). The outcome was most unfavourable following en bloc resection of large tumors (36% MFS) and of tumors poorly responding to preoperative chemotherapy. Delaying surgery for preoperative chemotherapy in itself did not influence MFS-rate but it enabled a thorough planing and preparation of surgical procedures. Chemotherapy has very much improved the prognosis of osteosarcoma, trials on limb salvage surgery are indicated therefore. However, these procedures appear to be hazardous by increasing the rate of pulmonary metastases. Until the underlying mechanisms are not uncovered and preventive strategies worked out, limb salvage surgery in osteosarcoma has to be regarded and handled as an experimental procedure.

Amputation, Surgical↗
PubMedDate not supplied

Figure-of-eight circulation in thoracopagus conjoined twins with a shared heart.

A pair of thoracopagus conjoined twins is described in whom a common heart with atrial and ventricular conjunction was demonstrated by cardiac catheterization and at autopsy. Each twin had an independent noncommunicating single ventricle with separate origins of the aorta and pulmonary arteries. A complex pattern of pulmonary and systemic venous return resulted in a fugure-of-eight circulation not previously described which precluded surgical intervention. This report demonstrates the feasibility of detailed hemodynamic assessment in thoracopagus twins and the value of selective ventricular angiography with careful observation of the venous phase in determining an accurate preoperative diagnosis.

Adult↗