[Atlanto-occipital dislocation-A challenge with respect to making the diagnosis and treatment]. / Atlantookzipitale Dislokation ­ eine Herausforderung hinsichtlich der Diagnosestellung und Therapie.

BACKGROUND: The correct diagnosis and treatment of the atlanto-occipital dislocation (AOD) remains a major challenge. OBJECTIVE: To evaluate the different radiological diagnostic criteria for AOD and discuss potential treatment strategies based on a case with AOD and additional fracture of the atlas. MATERIAL AND METHODS: A 29-year-old male patient is presented who suffered from AOD with concomitant fracture of the anterior and posterior arches of the atlas with rotational atlantoaxial dislocation following an accident in forestry. The following parameters were evaluated for the diagnosis and assessment of postoperative reduction: Powers ratio, the X­lines-method, Wackenheim line, basion-dens interval (BDI), basion-axial interval (BAI) and occipital condyle-C1 interval (CCI). RESULTS: Stabilization was performed by occipitocervical spondylodesis from C0 to C2/3. For final reduction it was necessary to reduce the malrotation of the atlas. In the presented case, the revised CCI proved to be a sensitive and valid yet practical parameter. Powers' ratio and the BDI were less suited for assessing the diagnosis. The X­lines-method, Wackenheim line and the BAI did not adequately detect the pathological situation. DISCUSSION: The AOD is a severe injury requiring immediate correct diagnosis for later adequate treatment results. Among the published parameters, the revised CCI proved to be a practical and valid parameter to detect AOD. For definitive treatment, the operative occipitocervical stabilization is regarded as the method of choice.

Self-organising maps for the exploration and classification of thin-layer chromatograms.

Thin-layer chromatography (TLC) allows the swift analysis of larger sample sets in almost any laboratory. The obtained chromatograms are patterns of coloured zones that are conveniently evaluated and classified by visual inspection. This manual approach reaches its limit when several dozens or a few hundred samples need to be evaluated. Methods to classify TLCs automatically and objectively have been explored but without a definitive conclusion; established methods, such as principal component analysis, suffer from the variability of the data, while contemporary omics methods were constructed for the analysis of large numbers of highly resolved analyses. Self-organizing maps (SOMs) are an algorithm for unsupervised learning that reduces higher dimensional datasets to a two-dimensional map, locating similar samples close to each other. It tolerates small variations between samples of the same type. We investigated the capability of SOMs for the evaluation of TLCs with two sample sets. With the first one (495 analyses of essential oils), it was confirmed that SOMs arrange the same type of sample in a common region. The obtained multi-class maps were used to classify a test set and to explore the causes for the few misclassifications (<3%). With the second test set (50 extracts of experimental wheats), the effects of a greater variability within substance classes was explored. With SOMs, it was possible to single out the exceptional samples that warranted a more detailed investigation. In addition, the SOM quality control index method was tested. It proved to be considerably stricter than the classification with a SOM of all samples. When this method was unable to classify a sample correctly, it would flag the sample for inspection, as it gave either multiple assignments or none at all. The combination of SOMs and TLC - two accessible analytical tools - can be most useful for the unsupervised classification of samples by TLC, and to identify samples that stand out from a set and are therefore worth the investment into additional analyses with more complex or expensive methods.

Unbreakable and customizable dipping chambers for TLC and HPTLC manufactured by fused deposition modelling.

Postchromatographic derivatization chambers for Thin Layer Chromatography (TLC) and its high-performance counterpart (HPTLC) are made of glass, which renders them fragile and - given their frequent use - eventually rather expensive. As a consequence, in daily lab routine, staining reagents are often kept in jars or beakers as cheap and available but unsatisfying equipment. This work describes the design and the manufacturing of shock-resistant and affordable dipping chambers from polypropylene (PP) by fused deposition modelling ("3D printing"). The design is implemented as a customizable script. Three chamber designs are presented: a chamber for typical HPTLC plates (20 × 10 cm) with a convenient closing/storing system which avoids awkward pouring and removal of staining reagents. Second, for synthesis purposes, a chamber for 10 × 10 cm plates with a spout to facilitate exchanging the staining reagent, as well as a very small chamber stabilized by a pedestal for reaction control on 2.5 × 7.5 cm plates, which limits the loss of costly staining reagent. Even though the chambers adsorbed some degraded staining reagent over time, no cross-contamination was observed. All customizable scripts (as CAD models) are made available through online repositories.