Compound Identification Using Liquid Chromatography and High-Resolution Noncontact Fraction Collection with a Solenoid Valve.

We describe the development of a high-resolution, noncontact fraction collector for liquid chromatography (LC) separations, allowing high-resolution fractionation in high-density well plates. The device is based on a low-dead-volume solenoid valve operated at 1-30 Hz for accurate collection of fractions of equal volume. The solenoid valve was implemented in a modified autosampler resulting in the so-called FractioMate fractionator. The influence of the solenoid supply voltage on solvent release was determined and the effect of the frequency, flow rate, and mobile phase composition was studied. For this purpose, droplet release was visually assessed for a wide range of frequencies and flow rates, followed by quantitative evaluation of a selection of promising settings for highly accurate, repeatable, and stable fraction collection. The potential of the new fraction collector for LC-based bioactivity screening was demonstrated by fractionating the LC eluent of a mixture of estrogenic and androgenic compounds, and a surface water sample (blank and spiked with bioactives) combining mass spectrometric detection and two reporter gene assays for bioactivity detection of the fractions. Additionally, a mixture of two compounds was repeatedly LC separated and fractionated to assess the feasibility of the system for analyte isolation followed by nuclear magnetic resonance analysis.

Moving the mandible in orthognathic surgery - A multicenter analysis.

Orthognathic surgery has always been a classical focus of maxillofacial surgery. Since more than 100 years, various surgical techniques for mandibular repositioning have been developed and clinically tested. Since the establishment of plate and screw osteosynthesis, orthognathic surgery became more stable and safe. Nowadays, different surgical methods for mobilising the mandible are existing. This international multicenter analysis (n = 51 hospitals) is providing first evidence based data for the current use of different surgical methods. The dominating techniques were Obwegeser/dal Pont (61%) followed by Hunsuck/Epker (37%) and Perthes/Schlössmann (29%). The main osteosynthesis materials were plates (82%), bicortical screws (23.5%), or a combination of both (5.9%). 47% of all centers reported to use several surgical methods at the same time, depending on the anatomical problem and the surgeon's preference. This shows that different surgical methods seem to work as comparable, safe, and reliable procedures in everydays clinical practise. On this basis, further prospective studies could evaluate possible advantages for our patients.

Vertical distraction osteogenesis of fibula transplants for mandibular reconstruction--a preliminary study.

INTRODUCTION: When reconstructing the mandible after tumour resection with a fibular graft, the mandible is often vertically deficient, making placement of dental implants impossible. PATIENTS: Segmental vertical distraction of the reconstructed mandible was performed in nine patients following tumour surgery between February 1998 and 2001. Their age was 14-65 years (average 46.3); all underwent radiotherapy with a dose of up to 55.6 Gy prior to tumour resection. Mandibular discontinuity was repaired with a microvascular fibular bone graft. All grafts had a vertical bone deficit ranging from 9 to 12 mm when compared with the non-resected part of the mandibles. METHODS: All patients underwent segmental vertical distraction of the transplants. The distraction devices were applied intraorally. Distraction of 1.0 mm/day was performed using a Martin distractor (TRACK 1.5) followed by 12 weeks retention time. RESULTS: The increase of vertical bone height was stable and enabled placement of dental implants without any complications. CONCLUSION: Vertical distraction osteogenesis may become a common procedure in the treatment of alveolar ridge deficiency resulting from transplanting fibulae for mandibular reconstruction following tumour surgery.