Riding injuries

The aim of this study was to investigate accidents which occur in connection with horse-riding. The material was found in a data base covering 14% of all case registered in Casualty Departments in Denmark. The number of horse-riding accidents has increased by 150% from 1986 to 1996. The majority of these were girls. The age group 10-19 years accounted for 61% of the accidents. The majority of injuries occurred on falling from the horse and particularly involved the upper part of the body. Out of 1250 injuries, 24% sustained a fracture: 64% were located to the upper extremities, and 19% lower extremities. One hundred patients required hospitalization: 29 for observation for concussion; 51 for reduction of fractures and osteosynthesis; 13 for contusion. Forty-five percent of the accidents happened in a riding arena and 25% in a stable. It is concluded that the proportion of horse-riding accidents is strongly on the increase in Ribe County.     

Post-translational heterocyclic backbone modifications in the 43-peptide antibiotic microcin B17. Structure elucidation and NMR study of a 13C,15N-labelled gyrase inhibitor

Microcin B17 (McB17), the first known gyrase inhibitor of peptidic nature, is produced by ribosomal synthesis and post-translational modification of the 69-residue precursor protein by an Escherichia coli strain. To elucidate the chemical structure of the mature 43-residue peptide antibiotic, fermentation and purification protocols were established and optimized which allowed the isolation and purification of substantial amounts of highly pure McB17 (non-labelled, 15N-labelled and 13C/15N-labelled peptide. By ultraviolet-absorption spectroscopy. HPLC-electrospray mass spectrometry and GC-mass spectrometry, amino acid analysis, protein sequencing, and, in particular, multidimensional NMR, we could demonstrate and unequivocally prove that the enzymic modification of the precursor backbone at Gly-Cys and Gly-Ser segments leads to the formation of 2-aminomethylthiazole-4-carboxylic acid and 2-aminomethyloxazole-4-carboxylic acid, respectively. In addition, two bicyclic modifications 2-(2-aminomethyloxazolyl)thiazole-4-carboxylic acid and 2-(2-aminomethylthiazolyl)oxazole-4-carboxylic acid were found that consist of directly linked thiazole and oxazole rings derived from one Gly-Ser-Cys and one Gly-Cys-Ser segment. Analogous to the thiazole and oxazole rings found in antitumor peptides of microbial and marine origin, these heteroaromatic ring systems of McB17 presumably play an important role in its gyrase-inhibiting activity, e.g. interacting with the DNA to trap the covalent protein-DNA intermediate of the breakage-reunion reaction of the gyrase.     

Localised visualisation of O2 consumption and H2O2 formation by means of SECM for the characterisation of fuel cell catalyst activity

Catalytic reduction of O₂ at metal catalysts either follows a 2-electron transfer pathway to the formation of H₂O₂ or a 4-electron transfer pathway to the formation of H₂O. The branching ratio of this reaction has a significant impact on the applicability of catalyst materials. The previously introduced oxygen competition mode of SECM, which allows high-resolution imaging of local O₂ consumption, has been extended to a potential-pulse sequence enabling the sequential detection of O₂ reduction followed by the detection of local H₂O₂ formation. Thus, not only the local catalytic activity of a catalyst can be visualised but, additionally, the degree of the branching can be estimated. The selectivity of a catalyst candidate can thereby be visualised sequentially to the elucidation of its activity. First results on the properties of electrodeposited Pt and Au test structures are shown demonstrating the feasibility to clearly distinguish catalyst activity and selectivity under variation of the polarisation potential.     

Textile solar light collectors based on models for polar bear hair

Concepts of technical fibers following models for the polar bear hair to be used for textile solar collectors are discussed. The approach to coat fibers with a thin layer into which fluorescent dyestuff was dispersed was studied experimentally. Modified fibers made of different polymers were characterized with respect to optical properties relevant for the bionic model. In the case of poly(methylmethacrylate) fibers, the envisaged effect could be achieved to high efficiency. The optical performance could be enhanced by ultrasonic dispersion of the dyestuff in the coating matrix. The effect is less significant in semi-crystalline fibers such as poly(ethylene terephthalate), which is attributed to diffuse scattering.